View source for Physics:Tropical cyclone

{{Short description|Rapidly rotating storm system}}
<noinclude> </noinclude>
[[File:Dramatic Views of Hurricane Florence from the International Space Station From 9 12 (42828603210).jpg|alt=View of a tropical cyclone from space|upright=1.5|thumb|Example of tropical cyclone Hurricane Florence in 2018 as viewed from space: The eye, eyewall, and surrounding rainbands are characteristics of tropical cyclones.]]
{{Tropicalcyclone}}
A '''tropical cyclone''' is a rapidly rotating [[Earth:Storm|storm system]] characterized by a [[Physics:Low-pressure area|low-pressure]] center, a closed low-level [[Earth:Atmospheric circulation|atmospheric circulation]], strong winds, and a spiral arrangement of [[Physics:Thunderstorm|thunderstorm]]s that produce heavy rain and [[Earth:Squall|squall]]s. Depending on its location and strength, a tropical cyclone is referred to by different names, including '''hurricane''' ({{IPAc-en|ˈ|h|ʌr|ᵻ|k|ən|,_|-|k|eɪ|n}}), '''typhoon''' ({{IPAc-en|t|aɪ|'|f|uː|n}}), '''tropical storm''', '''cyclonic storm''', '''tropical depression''', or simply '''cyclone'''. A [[Earth:Atlantic hurricane|hurricane]] is a strong tropical cyclone that occurs in the [[Earth:Atlantic Ocean|Atlantic Ocean]] or northeastern [[Earth:Pacific Ocean|Pacific Ocean]], and a [[Earth:Typhoon|typhoon]] occurs in the northwestern Pacific Ocean. In the [[Earth:Indian Ocean|Indian Ocean]] and South Pacific, comparable storms are referred to as "tropical cyclones". In modern times, on average around 80 to 90 named tropical cyclones form each year around the world, over half of which develop hurricane-force winds of {{convert|65|kn|km/h mph|lk=in|abbr=on|round=5}} or more.<ref name="Global Guide 2017">{{cite report |url=https://cyclone.wmo.int/pdf/Global-Guide-to-Tropical-Cyclone-Forecasting.pdf |title=Global Guide to Tropical Cyclone Forecasting: 2017 |date=April 17, 2018 |publisher=[[Organization:World Meteorological Organization|World Meteorological Organization]] |access-date=September 6, 2020 |archive-url=https://web.archive.org/web/20190714014847/https://cyclone.wmo.int/pdf/Global-Guide-to-Tropical-Cyclone-Forecasting.pdf |archive-date=July 14, 2019 |url-status=live}}</ref> Tropical cyclones carry heat and energy away from the tropics and transport it towards temperate latitudes, which plays an important role in [[Earth:Climate system|regulating global climate]]. 

Tropical cyclones [[Earth:Tropical cyclogenesis|typically form]] over large bodies of relatively warm water. They derive their energy through the evaporation of [[Chemistry:Water|water]] from the [[Earth:Ocean|ocean]] surface, which ultimately [[Physics:Condensation|condenses]] into [[Earth:Cloud|cloud]]s and rain when moist air rises and cools to saturation. This energy source differs from that of mid-latitude cyclonic storms, such as nor'easters and [[Earth:European windstorm|European windstorm]]s, which are powered primarily by [[Earth:Baroclinic instability|horizontal temperature contrasts]]. Tropical cyclones are typically between {{convert|100|and|2000|km|mi|abbr=on}} in diameter.  

The strong rotating winds of a tropical cyclone are a result of the conservation of angular momentum imparted by the [[Earth's rotation]] as air flows inwards toward the axis of rotation. As a result, cyclones rarely form within 5° of the [[Astronomy:Equator|equator]], although there have been some cases. Tropical cyclones are very rare in the South Atlantic (although [[Earth:South Atlantic tropical cyclone|occasional examples do occur]]) due to consistently strong [[Physics:Wind shear|wind shear]] and a weak [[Earth:Intertropical Convergence Zone|Intertropical Convergence Zone]]. Conversely, the [[Earth:African easterly jet|African easterly jet]] and areas of [[Earth:Atmospheric instability|atmospheric instability]] give rise to cyclones in the Atlantic Ocean and Caribbean Sea, while cyclones near Australia owe their genesis to the [[Earth:Monsoon of South Asia|Asian monsoon]] and Western Pacific Warm Pool.

The primary energy source for these storms is warm ocean waters. These storms are therefore typically strongest when over or near water, and they weaken quite rapidly over land. This causes coastal regions to be particularly vulnerable to tropical cyclones, compared to inland regions. Coastal damage may be caused by strong winds and rain, high waves (due to winds), [[Physics:Storm surge|storm surge]]s (due to wind and severe pressure changes), and [[Earth:Tornadogenesis|the potential]] of spawning [[Earth:Tornado|tornado]]es. 

Tropical cyclones draw in air from a large area and concentrate the water content of that air (from atmospheric moisture and moisture evaporated from water) into [[Earth:Precipitation|precipitation]] over a much smaller area. This replenishing of moisture-bearing air after rain may cause multi-hour or multi-day extremely heavy rain up to {{convert|40|km|mi|abbr=on}} from the coastline, far beyond the amount of water that the local atmosphere holds at any one time. This in turn can lead to river flooding, overland flooding, and a general overwhelming of local water control structures across a large area. The effects of tropical cyclones on human populations can be devastating, Every year tropical cyclones affect various regions of the globe including the Gulf Coast of North America, {{wipe|Australia}}, {{wipe|India}}, and Bangladesh. 

[[Earth:Climate change|Climate change]] can affect tropical cyclones in a variety of ways: an intensification of rainfall and wind speed, a decrease in overall frequency, an increase in the frequency of very intense storms and a poleward extension of where the cyclones reach maximum intensity are among the possible consequences of human-induced climate change.<ref name=":5" /> 

==Definition and terminology==
A tropical cyclone is the generic term for a warm-cored, non-frontal [[Earth:Synoptic scale meteorology|synoptic-scale]] [[Physics:Low-pressure area|low-pressure system]] over tropical or [[Earth:Subtropics|subtropical]] waters around the world.<ref name="Gloss">{{cite web |title=Glossary of NHC Terms |url=https://www.nhc.noaa.gov/aboutgloss.shtml |url-status=live |archive-url=https://web.archive.org/web/20210216200241/https://www.nhc.noaa.gov/aboutgloss.shtml |archive-date=February 16, 2021 |access-date=February 18, 2021 |publisher=[[Earth:National Hurricane Center|United States National Hurricane Center]]}}</ref><ref name="What">{{cite web |title=Tropical cyclone facts: What is a tropical cyclone? |url=https://www.metoffice.gov.uk/research/weather/tropical-cyclones/facts#What%20is%20a%20TC |url-status=live |archive-url=https://web.archive.org/web/20210202123840/https://www.metoffice.gov.uk/research/weather/tropical-cyclones/facts |archive-date=February 2, 2021 |access-date=February 25, 2021 |publisher=[[Company:Met Office|United Kingdom Met Office]]}}</ref> The systems generally have a well-defined center which is surrounded by deep [[Earth:Atmospheric convection|atmospheric convection]] and a closed wind circulation at the surface.<ref name="Gloss"/> A tropical cyclone is generally deemed to have formed once mean surface winds in excess of {{convert|35|kn|km/h mph|round=5|abbr=on}} are observed.<ref name="Global Guide 2017" /> It is assumed at this stage that a tropical cyclone has become self-sustaining and can continue to intensify without any help from its environment.<ref name="Global Guide 2017" />

Depending on its location and strength, a tropical cyclone is referred to by different names, including ''hurricane'', ''typhoon'', ''tropical storm'', ''cyclonic storm'', ''tropical depression'', or simply ''cyclone''. A [[Earth:Atlantic hurricane|hurricane]] is a strong tropical cyclone that occurs in the [[Earth:Atlantic Ocean|Atlantic Ocean]] or northeastern [[Earth:Pacific Ocean|Pacific Ocean]], and a [[Earth:Typhoon|typhoon]] occurs in the northwestern Pacific Ocean. In the [[Earth:Indian Ocean|Indian Ocean]] and South Pacific, comparable storms are referred to as "tropical cyclones", and such storms in the Indian Ocean can also be called "severe cyclonic storms".

''Tropical'' refers to the geographical origin of these systems, which form almost exclusively over tropical seas. ''[[Physics:Cyclone|Cyclone]]'' refers to their winds moving in a circle, whirling round their central clear [[Physics:Eye (cyclone)|eye]], with their surface winds blowing counterclockwise in the [[Earth:Northern Hemisphere|Northern Hemisphere]] and [[Physics:Clockwise|clockwise]] in the [[Earth:Southern Hemisphere|Southern Hemisphere]]. The opposite direction of circulation is due to the Coriolis effect. 

== Formation ==
{{Main|Earth:Tropical cyclogenesis}}
[[File:Hurricane-en.svg|thumb|upright=1.3|Diagram of a tropical cyclone in the Northern Hemisphere|alt=A schematic diagram of a tropical cyclone]]

Tropical cyclones tend to develop during the summer, but have been noted in nearly every month in most [[Earth:Tropical cyclone basins|tropical cyclone basins]]. Tropical cyclones on either side of the Equator generally have their origins in the [[Earth:Intertropical Convergence Zone|Intertropical Convergence Zone]], where winds blow from either the northeast or southeast.<ref name="Form">{{cite web |title=Tropical cyclone facts: How do tropical cyclones form? |url=https://www.metoffice.gov.uk/research/weather/tropical-cyclones/facts#How%20do%20TCs%20form |url-status=live |archive-url=https://web.archive.org/web/20210202123840/https://www.metoffice.gov.uk/research/weather/tropical-cyclones/facts |archive-date=February 2, 2021 |access-date=March 1, 2021 |publisher=United Kingdom Met Office}}</ref> Within this broad area of low-pressure, air is heated over the warm tropical ocean and rises in discrete parcels, which causes thundery showers to form.<ref name="Form" /> These showers dissipate quite quickly; however, they can group together into large clusters of thunderstorms.<ref name="Form" /> This creates a flow of warm, moist, rapidly rising air, which starts to [[Cyclonic rotation|rotate cyclonically]] as it interacts with the rotation of the earth.<ref name="Form" />

Several factors are required for these thunderstorms to develop further, including sea surface temperatures of around {{convert|27|°C|°F|abbr=on}} and low vertical [[Physics:Wind shear|wind shear]] surrounding the system,{{r|Form|A15}} atmospheric instability, high [[Physics:Humidity|humidity]] in the lower to middle levels of the [[Earth:Troposphere|troposphere]], enough [[Physics:Coriolis force|Coriolis force]] to develop a [[Physics:Low-pressure area|low-pressure center]], and a pre-existing low-level focus or disturbance.<ref name="A15">{{cite web |last=Landsea |first=Chris |title=How do tropical cyclones form? |url=http://www.aoml.noaa.gov/hrd/tcfaq/A15.html |url-status=live |archive-url=https://web.archive.org/web/20090827030639/http://www.aoml.noaa.gov/hrd/tcfaq/A15.html |archive-date=August 27, 2009 |access-date=October 9, 2017 |work=Frequently Asked Questions |publisher=[[Organization:Atlantic Oceanographic and Meteorological Laboratory|Atlantic Oceanographic and Meteorological Laboratory]], Hurricane Research Division}}</ref>
There is a limit on tropical cyclone intensity which is strongly related to the water temperatures along its path.<ref name="RSMAS">{{cite web |last=Berg |first=Robbie |title=Tropical cyclone intensity in relation to SST and moisture variability |url=http://ams.confex.com/ams/pdfpapers/37899.pdf |url-status=live |archive-url=https://web.archive.org/web/20110610113232/http://ams.confex.com/ams/pdfpapers/37899.pdf |archive-date=June 10, 2011 |access-date=September 23, 2010 |publisher=[[Organization:Rosenstiel School of Marine and Atmospheric Science|RSMAS]] ([[Organization:University of Miami|University of Miami]])}}</ref> and upper-level divergence.<ref>{{cite journal |last1=Zhang |first1=Da-Lin |last2=Zhu |first2=Lin |date=September 12, 2012 |title=Roles of upper-level processes in tropical cyclogenesis |url=https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053140 |journal=Geophysical Research Letters |publisher=AGU |volume=39 |issue=17 |bibcode=2012GeoRL..3917804Z |doi=10.1029/2012GL053140 |s2cid=53341455 |access-date=October 4, 2022}}</ref>
An average of 86 tropical cyclones of tropical storm intensity form annually worldwide. Of those, 47 reach strength higher than {{convert|74|mph|km/h|abbr=on|order=flip}}, and 20 become intense tropical cyclones (at least Category&nbsp;3 intensity on the [[Earth:Saffir–Simpson scale|Saffir–Simpson scale]]).<ref>{{cite web |author=Chris Landsea |date=January 4, 2000 |title=Climate Variability table&nbsp;— Tropical Cyclones |url=http://www.aoml.noaa.gov/hrd/Landsea/climvari/table.html |url-status=live |archive-url=https://web.archive.org/web/20121002045230/http://www.aoml.noaa.gov/hrd/Landsea/climvari/table.html |archive-date=October 2, 2012 |access-date=October 19, 2006 |publisher=[[Organization:Atlantic Oceanographic and Meteorological Laboratory|Atlantic Oceanographic and Meteorological Laboratory]], [[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]}}</ref>

Climate oscillations such as [[Earth:El Niño–Southern Oscillation|El Niño–Southern Oscillation]] (ENSO) and the [[Earth:Madden–Julian oscillation|Madden–Julian oscillation]] modulate the timing and frequency of tropical cyclone development.<ref name="AOML climt var">{{cite web |last=Landsea |first=Christopher |title=AOML Climate Variability of Tropical Cyclones paper |url=http://www.aoml.noaa.gov/hrd/Landsea/climvari/index.html |url-status=live |archive-url=https://web.archive.org/web/20211026211517/https://www.aoml.noaa.gov/hrd/Landsea/climvari/index.html |archive-date=October 26, 2021 |access-date=September 23, 2010 |publisher=Atlantic Oceanographic and Meteorological Laboratory}}</ref><ref>{{cite journal |last1=Aiyyer |first1=Anantha |last2=Molinari |first2=John |date=August 1, 2008 |title=MJO and Tropical Cyclogenesis in the Gulf of Mexico and Eastern Pacific: Case Study and Idealized Numerical Modeling |journal=Journal of the Atmospheric Sciences |publisher=American Meteorological Society |volume=65 |issue=8 |pages=2691–2704 |bibcode=2008JAtS...65.2691A |doi=10.1175/2007JAS2348.1 |s2cid=17409876 |doi-access=free}}</ref><ref>{{cite journal |last1=Zhao |first1=Chen |last2=Li |first2=Tim |date=October 20, 2018 |title=Basin dependence of the MJO modulating tropical cyclone genesis |url=https://link.springer.com/article/10.1007/s00382-018-4502-y |url-status=live |journal=Climate Dynamics |publisher=Springer |volume=52 |issue=9–10 |pages=6081–6096 |doi=10.1007/s00382-018-4502-y |s2cid=134747858 |archive-url=https://web.archive.org/web/20221002213931/https://link.springer.com/article/10.1007/s00382-018-4502-y |archive-date=October 2, 2022 |access-date=October 5, 2022}}</ref><ref>{{cite journal |last1=Camargo |first1=Suzana J. |last2=Emanuel |first2=Kerry A. |last3=Sobel |first3=Adam H. |date=October 1, 2007 |title=Use of a Genesis Potential Index to Diagnose ENSO Effects on Tropical Cyclone Genesis |journal=Journal of Climate |publisher=American Meteorological Society |volume=20 |issue=19 |pages=4819–4834 |bibcode=2007JCli...20.4819C |doi=10.1175/JCLI4282.1 |s2cid=17340459 |doi-access=free}}</ref> [[Rossby wave]]s can aid in the formation of a new tropical cyclone by disseminating the energy of an existing, mature storm.<ref>{{cite journal |last1=Molinari |first1=John |last2=Lombardo |first2=Kelly |last3=Vollaro |first3=David |date=April 1, 2007 |title=Tropical Cyclogenesis within an Equatorial Rossby Wave Packet |journal=Journal of the Atmospheric Sciences |publisher=American Meteorological Society |volume=64 |issue=4 |pages=1301–1317 |bibcode=2007JAtS...64.1301M |doi=10.1175/JAS3902.1 |s2cid=12920242 |doi-access=free}}</ref><ref>{{cite journal |last1=Li |first1=Tim |last2=Fu |first2=Bing |date=May 1, 2006 |title=Tropical Cyclogenesis Associated with Rossby Wave Energy Dispersion of a Preexisting Typhoon. Part I: Satellite Data Analyses |journal=Journal of the Atmospheric Sciences |publisher=American Meteorological Society |volume=63 |issue=5 |pages=1377–1389 |bibcode=2006JAtS...63.1377L |doi=10.1175/JAS3692.1 |s2cid=15372289 |doi-access=free}}</ref> [[Physics:Kelvin wave|Kelvin wave]]s can contribute to tropical cyclone formation by regulating the development of the [[Earth:Westerlies|westerlies]].<ref>{{cite journal |last1=Schreck III |first1=Carl J. |last2=Molinari |first2=John |date=September 1, 2011 |title=Tropical Cyclogenesis Associated with Kelvin Waves and the Madden–Julian Oscillation |journal=Monthly Weather Review |publisher=American Meteorological Society |volume=139 |issue=9 |pages=2723–2734 |bibcode=2011MWRv..139.2723S |doi=10.1175/MWR-D-10-05060.1 |s2cid=16983131 |doi-access=free}}</ref> Cyclone formation is usually reduced 3 days prior to the wave's crest and increased during the 3 days after.<ref>{{cite journal |last1=Schreck III |first1=Carl J. |date=October 1, 2015 |title=Kelvin Waves and Tropical Cyclogenesis: A Global Survey |journal=Monthly Weather Review |publisher=American Meteorological Society |volume=143 |issue=10 |pages=3996–4011 |bibcode=2015MWRv..143.3996S |doi=10.1175/MWR-D-15-0111.1 |s2cid=118859063 |doi-access=free}}</ref>

=== Formation regions and warning centers ===
{| class="wikitable"
! colspan="4" style="background: #ccf;" |Tropical cyclone basins and official warning centers
|-
! scope="col" | Basin
! scope="col" | Warning center
! scope="col" | Area of responsibility
! scope="col" | Notes
|-
| colspan="4" style="text-align: center;" |'''Northern Hemisphere'''
|-
! scope="row" | [[Earth:Atlantic hurricane|North Atlantic]]
| United States [[Earth:National Hurricane Center|National Hurricane Center]] (Miami)
| Equator northward, African Coast&nbsp;– 140°W
| <ref name="ATL/EPAC TCOP" />
|-
! scope="row" | [[Earth:Pacific hurricane|Eastern Pacific]]
| United States [[Earth:Central Pacific Hurricane Center|Central Pacific Hurricane Center]] (Honolulu)
| Equator northward, 140–180°W
| <ref name="ATL/EPAC TCOP" />
|-
! scope="row" | [[Earth:Typhoon|Western Pacific]]
| Japan Meteorological Agency
| Equator –&nbsp;60°N, 180–100°E
| <ref name="WPAC TCOP">{{cite report |url=https://www.wmo.int/pages/prog/www/tcp/documents/TCP-23EDITION2015.pdf |title=Typhoon Committee Operational Manual Meteorological Component 2015 |author=WMO/ESCP Typhoon Committee |date=March 13, 2015 |publisher=[[Organization:World Meteorological Organization|World Meteorological Organization]] |pages=40–41 |access-date=March 28, 2015 |archive-url=https://web.archive.org/web/20151001064907/https://www.wmo.int/pages/prog/www/tcp/documents/TCP-23EDITION2015.pdf |archive-date=October 1, 2015 |url-status=live |type=Report No. TCP-23}}</ref>
|-
! scope="row" | North Indian Ocean
| India Meteorological Department
| Equator northwards, 100–40°E
| <ref name="NIO TCOP" />
|-
| colspan="4" style="text-align: center;" |'''Southern Hemisphere'''
|-
! scope="row" | South-West<br />Indian Ocean
| Météo-France Reunion
| Equator – 40°S, African Coast –&nbsp;90°E
| <ref name="SWIO TCOP" />
|-
! rowspan="3" scope="row" | Australian region
| Indonesian Meteorology, Climatology,<br /> and Geophysical Agency (BMKG)
| Equator – 10°S, 90–141°E
| {{RA V Tropical cyclone operational plan}}<!-- defines <ref name="SPAC TCOP"/> -->
|-
| Papua New Guinea National Weather Service
| Equator – 10°S, 141–160°E
| <ref name="SPAC TCOP" />
|-
| Australian Bureau of Meteorology
| 10–40°S, 90–160°E
| <ref name="SPAC TCOP" />
|-
! rowspan="2" scope="row" | Southern Pacific
| Fiji Meteorological Service
| Equator&nbsp;– 25°S, 160°E&nbsp;– 120°W
| <ref name="SPAC TCOP" />
|-
| Meteorological Service of New Zealand
| 25–40°S, 160°E – 120°W
| <ref name="SPAC TCOP" />
|}

The majority of tropical cyclones each year form in one of seven tropical cyclone basins, which are monitored by a variety of meteorological services and warning centres.<ref name="Global Guide 2017" /> Ten of these warning centres worldwide are designated as either a Regional Specialized Meteorological Centre or a Tropical Cyclone Warning Centre by the World Meteorological Organization's (WMO) tropical cyclone programme.<ref name="Global Guide 2017" /> These warning centres issue advisories which provide basic information and cover a systems present, forecast position, movement and intensity, in their designated areas of responsibility.<ref name="Global Guide 2017" /> Meteorological services around the world are generally responsible for issuing warnings for their own country, however, there are exceptions, as the United States National Hurricane Center and Fiji Meteorological Service issue alerts, watches and warnings for various island nations in their areas of responsibility.<ref name="Global Guide 2017" /><ref name="SPAC TCOP" /> The United States [[Earth:Joint Typhoon Warning Center|Joint Typhoon Warning Center]] and Fleet Weather Center also publicly issue warnings, about tropical cyclones on behalf of the United States Government.<ref name="Global Guide 2017" /> The Brazilian Navy Hydrographic Center names [[Earth:South Atlantic tropical cyclone|South Atlantic tropical cyclone]]s, however the South Atlantic is not a major basin, and not an official basin according to the WMO.<ref name="names_2011">{{cite web |year=2011 |title=Normas Da Autoridade Marítima Para As Atividades De Meteorologia Marítima |url=https://www.marinha.mil.br/dhn/sites/www.marinha.mil.br.dhn/files/normam/normam_19.pdf |url-status=dead |archive-url=https://web.archive.org/web/20150206213534/http://www.mar.mil.br/dhn/dhn/downloads/normam/normam_19.pdf |archive-date=February 6, 2015 |access-date=October 5, 2018 |publisher=Brazilian Navy |language=pt}}</ref>

== Intensity ==
Tropical cyclone intensity is based on wind speeds and pressure; relationships between winds and pressure are often used in determining the intensity of a storm.<ref>{{cite journal |last1=Knapp |first1=Kenneth R. |last2=Knaff |first2=John A. |last3=Sampson |first3=Charles R. |last4=Riggio |first4=Gustavo M. |last5=Schnapp |first5=Adam D. |title=A Pressure-Based Analysis of the Historical Western North Pacific Tropical Cyclone Intensity Record |journal=Monthly Weather Review |date=August 1, 2013 |volume=141 |issue=8 |pages=2611–2631 |doi=10.1175/MWR-D-12-00323.1 |publisher=American Meteorological Society |bibcode=2013MWRv..141.2611K |s2cid=19031120 |doi-access=free }}</ref> Tropical cyclone scales such as the Saffir-Simpson Hurricane Wind Scale and Australia's scale (Bureau of Meteorology) only use wind speed for determining the category of a storm.<ref>{{cite web |title=What is a Tropical Cyclone? |url=http://www.bom.gov.au/cyclone/tropical-cyclone-knowledge-centre/understanding/tc-info/ |publisher=Bureau of Meteorology |access-date=October 7, 2022 |archive-date=October 3, 2022 |archive-url=https://web.archive.org/web/20221003062556/http://www.bom.gov.au/cyclone/tropical-cyclone-knowledge-centre/understanding/tc-info/ |url-status=live }}</ref><ref>{{cite web |title=Saffir-Simpson Hurricane Wind Scale |url=https://www.nhc.noaa.gov/aboutsshws.php |publisher=National Hurricane Center |access-date=October 7, 2022 |archive-date=June 20, 2020 |archive-url=https://web.archive.org/web/20200620093804/https://www.nhc.noaa.gov/aboutsshws.php |url-status=live }}</ref> The most intense storm on record is Typhoon Tip in the northwestern Pacific Ocean in 1979, which reached a minimum pressure of {{convert|870|hPa|inHg|lk=on|abbr=on}} and maximum sustained wind speeds of {{convert|165|kn|m/s km/h mph|abbr=on|round=5}}.<ref name="jtwc">{{Cite journal |last1=Dunnavan |first1=G.M. |last2=Diercks |first2=J.W. |year=1980 |title=An Analysis of Super Typhoon Tip (October 1979) |journal=Monthly Weather Review |volume=108 |issue=11 |pages=1915–1923 |bibcode=1980MWRv..108.1915D |doi=10.1175/1520-0493(1980)108<1915:AAOSTT>2.0.CO;2 |doi-access=free}}</ref> The highest maximum sustained wind speed ever recorded was {{convert|185|kn|m/s km/h mph|abbr=on|round=5}} in Hurricane Patricia in 2015—the most intense cyclone ever recorded in the [[Earth:Western Hemisphere|Western Hemisphere]].<ref>{{cite web|last1=Pasch|first1=Richard|title=Hurricane Patricia Discussion Number 14|url=http://www.nhc.noaa.gov/text/refresh/MIATCDEP5+shtml/230834.shtml?|publisher=National Hurricane Center|date=October 23, 2015|quote=Data from three center fixes by the Hurricane Hunters indicate that the intensity, based on a blend of 700 mb-flight level and SFMR-observed surface winds, is near 175 kt. This makes Patricia the strongest hurricane on record in the National Hurricane Center's area of responsibility (AOR) which includes the Atlantic and the eastern North Pacific basins.|access-date=October 23, 2015|archive-url=https://web.archive.org/web/20151025142113/http://www.nhc.noaa.gov/text/refresh/MIATCDEP5+shtml/230834.shtml|archive-date=October 25, 2015|url-status=live}}</ref>

===Factors that influence intensity===
Warm [[Physics:Sea surface temperature|sea surface temperature]]s are required in order for tropical cyclones to form and strengthen. The commonly-accepted minimum temperature range for this to occur is {{convert|26–27|C|F|abbr=on}}, however, multiple studies have proposed a lower minimum of {{convert|25.5|C|F|abbr=on}}.<ref>{{cite journal |last1=Tory |first1=K. J. |last2=Dare |first2=R. A. |date=October 15, 2015 |title=Sea Surface Temperature Thresholds for Tropical Cyclone Formation |url=https://journals.ametsoc.org/view/journals/clim/28/20/jcli-d-14-00637.1.xml?tab_body=pdf |url-status=live |journal=Journal of Climate |publisher=American Meteorological Society |volume=28 |issue=20 |page=8171 |bibcode=2015JCli...28.8171T |doi=10.1175/JCLI-D-14-00637.1 |archive-url=https://web.archive.org/web/20210428230055/https://journals.ametsoc.org/view/journals/clim/28/20/jcli-d-14-00637.1.xml?tab_body=pdf |archive-date=April 28, 2021 |access-date=April 28, 2021 |doi-access=free}}</ref><ref>{{cite journal |last1=Lavender |first1=Sally |last2=Hoeke |first2=Ron |last3=Abbs |first3=Deborah |date=March 9, 2018 |title=The influence of sea surface temperature on the intensity and associated storm surge of tropical cyclone Yasi: a sensitivity study |url=https://nhess.copernicus.org/articles/18/795/2018/ |url-status=live |journal=Natural Hazards and Earth System Sciences |publisher=[[Company:Copernicus Publications|Copernicus Publications]] |volume=18 |issue=3 |pages=795–805 |bibcode=2018NHESS..18..795L |doi=10.5194/nhess-18-795-2018 |archive-url=https://web.archive.org/web/20210428224550/https://nhess.copernicus.org/articles/18/795/2018/ |archive-date=April 28, 2021 |access-date=April 28, 2021 |doi-access=free }}</ref> Higher sea surface temperatures result in faster intensification rates and sometimes even [[Earth:Rapid intensification|rapid intensification]].<ref>{{cite journal |last1=Xu |first1=Jing |last2=Wang |first2=Yuqing |date=April 1, 2018 |title=Dependence of Tropical Cyclone Intensification Rate on Sea SurfaceTemperature, Storm Intensity, and Size in the Western North Pacific |url=https://journals.ametsoc.org/view/journals/wefo/33/2/waf-d-17-0095_1.xml?tab_body=pdf |url-status=live |journal=Weather and Forecasting |publisher=American Meteorological Society |volume=33 |issue=2 |pages=523–527 |bibcode=2018WtFor..33..523X |doi=10.1175/WAF-D-17-0095.1 |archive-url=https://web.archive.org/web/20210428230055/https://journals.ametsoc.org/view/journals/wefo/33/2/waf-d-17-0095_1.xml?tab_body=pdf |archive-date=April 28, 2021 |access-date=April 28, 2021 |doi-access=free}}</ref> High [[Earth:Ocean heat content|ocean heat content]], also known as [[Earth:Tropical Cyclone Heat Potential|Tropical Cyclone Heat Potential]], allows storms to achieve a higher intensity.<ref name="NHC Intensity Forecasting">{{cite web |last1=Brown |first1=Daniel |title=Tropical Cyclone Intensity Forecasting: Still a Challenging Proposition |url=https://www.nhc.noaa.gov/outreach/presentations/NHC2017_IntensityChallenges.pdf |publisher=National Hurricane Center |access-date=April 27, 2021 |page=7 |date=April 20, 2017 |archive-date=April 27, 2021 |archive-url=https://web.archive.org/web/20210427013208/https://www.nhc.noaa.gov/outreach/presentations/NHC2017_IntensityChallenges.pdf |url-status=live }}</ref> Most tropical cyclones that experience rapid intensification are traversing regions of high ocean heat content rather than lower values.<ref name="OHC"/> High ocean heat content values can help to offset the oceanic cooling caused by the passage of a tropical cyclone, limiting the effect this cooling has on the storm.<ref>{{cite journal |last1=Lin |first1=I. |last2=Goni |first2=Gustavo |last3=Knaff |first3=John |last4=Forbes |first4=Cristina |last5=Ali |first5=M. |date=May 31, 2012 |title=Ocean heat content for tropical cyclone intensity forecasting and its impact on storm surge |url=https://www.aoml.noaa.gov/phod/docs/I-Ilin.pdf |url-status=live |journal=Journal of the International Society for the Prevention and Mitigation of Natural Hazards |publisher=[[Company:Springer Science+Business Media|Springer Science+Business Media]] |volume=66 |issue=3 |pages=3–4 |doi=10.1007/s11069-012-0214-5 |issn=0921-030X |archive-url=https://web.archive.org/web/20210427013210/https://www.aoml.noaa.gov/phod/docs/I-Ilin.pdf |archive-date=April 27, 2021 |access-date=April 27, 2021 |s2cid=9130662}}</ref> Faster-moving systems are able to intensify to higher intensities with lower ocean heat content values. Slower-moving systems require higher values of ocean heat content to achieve the same intensity.<ref name="OHC">{{cite journal |last1=Chih |first1=Cheng-Hsiang |last2=Wu |first2=Chun-Chieh |title=Exploratory Analysis of Upper-Ocean Heat Content and Sea Surface Temperature Underlying Tropical Cyclone Rapid Intensification in the Western North Pacific |journal=Journal of Climate |date=February 1, 2020 |volume=33 |issue=3 |pages=1031–1033 |doi=10.1175/JCLI-D-19-0305.1 |bibcode=2020JCli...33.1031C |s2cid=210249119 |url=https://journals.ametsoc.org/view/journals/clim/33/3/jcli-d-19-0305.1.xml?tab_body=pdf |access-date=April 27, 2021 |archive-date=April 27, 2021 |archive-url=https://web.archive.org/web/20210427013208/https://journals.ametsoc.org/view/journals/clim/33/3/jcli-d-19-0305.1.xml?tab_body=pdf |url-status=live }}</ref>

The passage of a tropical cyclone over the ocean causes the upper layers of the ocean to cool substantially, a process known as [[Earth:Upwelling|upwelling]],<ref>{{cite journal |last1=Hu |first1=Jianyu |last2=Wang |first2=Xiao Hua |date=September 2016 |title=Progress on upwelling studies in the China seas |journal=[[Earth:Reviews of Geophysics|Reviews of Geophysics]] |publisher=AGU |volume=54 |issue=3 |pages=653–673 |bibcode=2016RvGeo..54..653H |doi=10.1002/2015RG000505 |s2cid=132158526 |doi-access=free }}</ref> which can negatively influence subsequent cyclone development. This cooling is primarily caused by wind-driven mixing of cold water from deeper in the ocean with the warm surface waters. This effect results in a negative feedback process that can inhibit further development or lead to weakening. Additional cooling may come in the form of cold water from falling raindrops (this is because the atmosphere is cooler at higher altitudes). Cloud cover may also play a role in cooling the ocean, by shielding the ocean surface from direct sunlight before and slightly after the storm passage. All these effects can combine to produce a dramatic drop in sea surface temperature over a large area in just a few days.<ref name="NASA Cooling">{{cite web|author1=D'Asaro, Eric A. |author2=Black, Peter G. |name-list-style=amp |url=https://ams.confex.com/ams/last2000/techprogram/paper_12726.htm |title=J8.4 Turbulence in the Ocean Boundary Layer Below Hurricane Dennis |year=2006 |access-date=February 22, 2008 |publisher=[[Organization:University of Washington|University of Washington]] |url-status=live |archive-url=https://web.archive.org/web/20120330131407/http://iop.apl.washington.edu/opd/user/dasaro/DENNIS/HurrConf.pdf |archive-date=March 30, 2012 }}</ref> Conversely, the mixing of the sea can result in heat being inserted in deeper waters, with [[Earth:Cyclonic Niño|potential effects]] on global [[Earth:Climate|climate]].<ref>{{cite journal |last1=Fedorov |first1=Alexey V. |last2=Brierley |first2=Christopher M. |last3=Emanuel |first3=Kerry |date=February 2010 |title=Tropical cyclones and permanent El Niño in the early Pliocene epoch |journal=Nature |language=en |volume=463 |issue=7284 |pages=1066–1070 |bibcode=2010Natur.463.1066F |doi=10.1038/nature08831 |issn=0028-0836 |pmid=20182509 |hdl-access=free |hdl=1721.1/63099 |s2cid=4330367}}</ref>

[[Physics:Wind shear#Vertical component|Vertical wind shear]] decreases tropical cyclone predicability, with storms exhibiting wide range of responses in the presence of shear.<ref>{{cite journal |last1=Zhang |first1=Fuqing |last2=Tao |first2=Dandan |title=Effects of Vertical Wind Shear on the Predictability of Tropical Cyclones |journal=Journal of the Atmospheric Sciences |date=1 March 2013 |volume=70 |issue=3 |pages=975–983 |doi=10.1175/JAS-D-12-0133.1 |doi-access=free|bibcode=2013JAtS...70..975Z }}</ref> Wind shear often negatively affects tropical cyclone intensification by displacing moisture and heat from a system's center.<ref>{{cite web |last1=Stovern |first1=Diana |last2=Ritchie |first2=Elizabeth |title=Modeling the Effect of Vertical Wind Shear on Tropical Cyclone Size and Structure |pages=1–2 |url=https://ams.confex.com/ams/pdfpapers/169136.pdf |access-date=April 28, 2021 |website=American Meteorological Society |archive-date=June 18, 2021 |archive-url=https://web.archive.org/web/20210618212223/https://ams.confex.com/ams/pdfpapers/169136.pdf |url-status=live }}</ref> Low levels of vertical wind shear are most optimal for strengthening, while stronger wind shear induces weakening.<ref>{{cite journal |last1=Wingo |first1=Matthew |last2=Cecil |first2=Daniel |title=Effects of Vertical Wind Shear on Tropical Cyclone Precipitation |journal=Monthly Weather Review |date=March 1, 2010 |volume=138 |issue=3 |pages=645–662 |doi=10.1175/2009MWR2921.1 |publisher=American Meteorological Society |bibcode=2010MWRv..138..645W |s2cid=73622535 |doi-access=free }}</ref><ref>{{cite journal |last1=Liang |first1=Xiuji |last2=Li |first2=Qingqing |date=March 1, 2021 |title=Revisiting the response of western North Pacific tropical cyclone intensity change to vertical wind shear in different directions |journal=Atmospheric and Oceanic Science Letters |volume=14 |issue=3 |page=100041 |doi=10.1016/j.aosl.2021.100041 |bibcode=2021AOSL...1400041L |doi-access=free}}</ref> Dry air entraining into a tropical cyclone's core has a negative effect on its development and intensity by diminishing atmospheric convection and introducing asymmetries in the storm's structure.<ref>{{cite journal |last1=Shi |first1=Donglei |last2=Ge |first2=Xuyang |last3=Peng |first3=Melinda |title=Latitudinal dependence of the dry air effect on tropical cyclone development |journal=Dynamics of Atmospheres and Oceans |date=September 2019 |volume=87 |page=101102 |doi=10.1016/j.dynatmoce.2019.101102 |url=https://www.sciencedirect.com/science/article/abs/pii/S0377026519300193 |access-date=May 14, 2022 |bibcode=2019DyAtO..8701102S |s2cid=202123299 }}</ref><ref>{{cite journal |last1=Wang |first1=Shuai |last2=Toumi |first2=Ralf |date=June 1, 2019 |title=Impact of Dry Midlevel Air on the Tropical Cyclone Outer Circulation |journal=Journal of the Atmospheric Sciences |publisher=American Meteorological Society |volume=76 |issue=6 |pages=1809–1826 |bibcode=2019JAtS...76.1809W |doi=10.1175/JAS-D-18-0302.1 |hdl=10044/1/70065 |s2cid=145965553|doi-access=free |hdl-access=free }}</ref><ref>{{cite journal |last1=Alland |first1=Joshua J. |last2=Tang |first2=Brian H. |last3=Corbosiero |first3=Kristen L. |last4=Bryan |first4=George H. |title=Combined Effects of Midlevel Dry Air and Vertical Wind Shear on Tropical Cyclone Development. Part II: Radial Ventilation |journal=Journal of the Atmospheric Sciences |date=February 24, 2021 |volume=78 |issue=3 |pages=783–796 |doi=10.1175/JAS-D-20-0055.1 |url=https://journals.ametsoc.org/view/journals/atsc/78/3/JAS-D-20-0055.1.xml |access-date=May 14, 2022 |publisher=American Meteorological Society |bibcode=2021JAtS...78..783A |s2cid=230602004 |archive-date=May 14, 2022 |archive-url=https://web.archive.org/web/20220514132936/https://journals.ametsoc.org/view/journals/atsc/78/3/JAS-D-20-0055.1.xml |url-status=live }}</ref> Symmetric, strong [[Astronomy:Outflow (meteorology)|outflow]] leads to a faster rate of intensification than observed in other systems by mitigating local wind shear.<ref>{{cite journal |last1=Rappin |first1=Eric D. |last2=Morgan |first2=Michael C. |last3=Tripoli |first3=Gregory J. |title=The Impact of Outflow Environment on Tropical Cyclone Intensification and Structure |journal=Journal of the Atmospheric Sciences |date=February 1, 2011 |volume=68 |issue=2 |pages=177–194 |doi=10.1175/2009JAS2970.1 |publisher=American Meteorological Society |bibcode=2011JAtS...68..177R |s2cid=123508815 |doi-access=free }}</ref><ref>{{cite journal |last1=Shi |first1=Donglei |last2=Chen |first2=Guanghua |title=The Implication of Outflow Structure for the Rapid Intensification of Tropical Cyclones under Vertical Wind Shear |journal=Monthly Weather Review |date=December 10, 2021 |volume=149 |issue=12 |pages=4107–4127 |doi=10.1175/MWR-D-21-0141.1 |url=https://journals.ametsoc.org/view/journals/mwre/149/12/MWR-D-21-0141.1.xml |access-date=May 15, 2022 |publisher=American Meteorological Society |bibcode=2021MWRv..149.4107S |s2cid=244001444 |archive-date=May 14, 2022 |archive-url=https://web.archive.org/web/20220514131433/https://journals.ametsoc.org/view/journals/mwre/149/12/MWR-D-21-0141.1.xml |url-status=live }}</ref><ref>{{cite journal |last1=Ryglicki |first1=David R. |last2=Doyle |first2=James D. |last3=Hodyss |first3=Daniel |last4=Cossuth |first4=Joshua H. |last5=Jin |first5=Yi |last6=Viner |first6=Kevin C. |last7=Schmidt |first7=Jerome M. |title=The Unexpected Rapid Intensification of Tropical Cyclones in Moderate Vertical Wind Shear. Part III: Outflow–Environment Interaction |journal=Monthly Weather Review |date=August 1, 2019 |volume=147 |issue=8 |pages=2919–2940 |doi=10.1175/MWR-D-18-0370.1 |publisher=American Meteorological Society |bibcode=2019MWRv..147.2919R |s2cid=197485216 |doi-access=free }}</ref> Weakening outflow is associated with the weakening of [[Earth:Rainband|rainbands]] within a tropical cyclone.<ref>{{cite journal |last1=Dai |first1=Yi |last2=Majumdar |first2=Sharanya J. |last3=Nolan |first3=David S. |title=The Outflow–Rainband Relationship Induced by Environmental Flow around Tropical Cyclones |journal=Journal of the Atmospheric Sciences |date=July 1, 2019 |volume=76 |issue=7 |pages=1845–1863 |doi=10.1175/JAS-D-18-0208.1 |publisher=American Meteorological Society |bibcode=2019JAtS...76.1845D |s2cid=146062929 |doi-access=free }}</ref> Tropical cyclones may still intensify, even rapidly, in the presence of moderate or strong wind shear depending on the evolution and structure of the storm's convection.<ref>{{cite journal |last1=Ryglicki |first1=David R. |last2=Cossuth |first2=Joshua H. |last3=Hodyss |first3=Daniel |last4=Doyle |first4=James D. |title=The Unexpected Rapid Intensification of Tropical Cyclones in Moderate Vertical Wind Shear. Part I: Overview and Observations |journal=Monthly Weather Review |date=1 November 2018 |volume=146 |issue=11 |pages=3773–3800 |doi=10.1175/MWR-D-18-0020.1|doi-access=free|bibcode=2018MWRv..146.3773R }}</ref><ref>{{cite journal |last1=Rios-Berrios |first1=Rosimar |last2=Finocchio |first2=Peter M. |last3=Alland |first3=Joshua J. |last4=Chen |first4=Xiaomin |last5=Fischer |first5=Michael S. |last6=Stevenson |first6=Stephanie N. |last7=Tao |first7=Dandan |title=A Review of the Interactions between Tropical Cyclones and Environmental Vertical Wind Shear |journal=Journal of the Atmospheric Sciences |date=27 October 2023 |doi=10.1175/JAS-D-23-0022.1}}</ref>

The size of tropical cyclones plays a role in how quickly they intensify. Smaller tropical cyclones are more prone to rapid intensification than larger ones.<ref>{{cite journal |last1=Carrasco |first1=Cristina |last2=Landsea |first2=Christopher |last3=Lin |first3=Yuh-Lang |title=The Influence of Tropical Cyclone Size on Its Intensification |journal=Weather and Forecasting |date=June 1, 2014 |volume=29 |issue=3 |pages=582–590 |doi=10.1175/WAF-D-13-00092.1 |publisher=American Meteorological Society |bibcode=2014WtFor..29..582C |s2cid=18429068 |doi-access=free }}</ref> The [[Physics:Fujiwhara effect|Fujiwhara effect]], which involves interaction between two tropical cyclones, can weaken and ultimately result in the dissipation of the weaker of two tropical cyclones by reducing the organization of the system's convection and imparting horizontal wind shear.<ref>{{cite journal |last1=Lander |first1=Mark |last2=Holland |first2=Greg J. |date=October 1993 |title=On the interaction of tropical-cyclone-scale vortices. I: Observations |url=https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.49711951406 |journal=Quarterly Journal of the Royal Meteorological Society |publisher=Royal Meteorological Society |volume=119 |issue=514 |pages=1347–1361 |bibcode=1993QJRMS.119.1347L |doi=10.1002/qj.49711951406 }}</ref> Tropical cyclones typically weaken while situated over a landmass because conditions are often unfavorable as a result of the lack of oceanic forcing.<ref>{{cite journal |last1=Andersen |first1=Theresa K. |last2=Shepherd |first2=J. Marshall |title=A global spatiotemporal analysis of inland tropical cyclone maintenance or intensification |journal=International Journal of Climatology |date=March 21, 2013 |volume=34 |issue=2 |pages=391–402 |doi=10.1002/joc.3693 |url=https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.3693 |access-date=October 7, 2022 |publisher=Royal Meteorological Society|s2cid=129080562 }}</ref> The [[Earth:Brown ocean effect|Brown ocean effect]] can allow a tropical cyclone to maintain or increase its intensity following [[Earth:Landfall|landfall]], in cases where there has been copious rainfall, through the release of latent heat from the saturated soil.<ref>{{cite book |last1=Andersen |first1=Theresa |chapter-url=https://link.springer.com/chapter/10.1007/978-3-319-47594-3_5 |title=Hurricanes and Climate Change |last2=Sheperd |first2=Marshall |date=February 17, 2017 |publisher=[[Company:Springer Publishing|Springer]] |isbn=978-3-319-47592-9 |pages=117–134 |chapter=Inland Tropical Cyclones and the "Brown Ocean" Concept |doi=10.1007/978-3-319-47594-3_5 |access-date=May 20, 2022 |archive-url=https://web.archive.org/web/20220515125238/https://link.springer.com/chapter/10.1007/978-3-319-47594-3_5 |archive-date=May 15, 2022 |url-status=live}}</ref> [[Earth:Orographic lift|Orographic lift]] can cause an significant increase in the intensity of the convection of a tropical cyclone when its eye moves over a mountain, breaking the capped boundary layer that had been restraining it.<ref>{{cite journal |last1=Houze |first1=Robert A. Jr. |title=Orographic effects on precipitating clouds |journal=Reviews of Geophysics |date=January 6, 2012 |volume=50 |issue=1 |doi=10.1029/2011RG000365 |publisher=AGU |bibcode=2012RvGeo..50.1001H |s2cid=46645620 |doi-access=free }}</ref> Jet streams can both enhance and inhibit tropical cyclone intensity by influencing the storm's outflow as well as vertical wind shear.<ref>{{cite journal |last1=Ito |first1=Kosuke |last2=Ichikawa |first2=Hana |title=Warm ocean accelerating tropical cyclone Hagibis (2019) through interaction with a mid-latitude westerly jet |journal=Scientific Online Letters on the Atmosphere |date=August 31, 2020 |volume=17A |pages=1–6 |doi=10.2151/sola.17A-001 |url=https://www.jstage.jst.go.jp/article/sola/advpub/0/advpub_17A-001/_pdf/-char/ja |access-date=October 7, 2022 |publisher=Meteorological Society of Japan |s2cid=224874804 |archive-date=October 7, 2022 |archive-url=https://web.archive.org/web/20221007004526/https://www.jstage.jst.go.jp/article/sola/advpub/0/advpub_17A-001/_pdf/-char/ja |url-status=live |doi-access=free }}</ref><ref>{{cite journal |last1=Do |first1=Gunwoo |last2=Kim |first2=Hyeong-Seog |title=Effect of Mid-Latitude Jet Stream on the Intensity of Tropical Cyclones Affecting Korea: Observational Analysis and Implication from the Numerical Model Experiments of Typhoon Chaba (2016) |journal=Atmosphere |date=August 18, 2021 |volume=12 |issue=8 |page=1061 |doi=10.3390/atmos12081061 |publisher=MDPI |bibcode=2021Atmos..12.1061D |doi-access=free }}</ref>

===Rapid intensification===
{{main|Earth:Rapid intensification}}
On occasion, tropical cyclones may undergo a process known as rapid intensification, a period in which the maximum sustained winds of a tropical cyclone increase by {{Convert|30|kn|km/h mph|lk=in|abbr=on}} or more within 24 hours.<ref name="NWS Glossary">{{cite web|title=Glossary of NHC Terms|url=https://www.nhc.noaa.gov/aboutgloss.shtml#r|publisher=United States National Oceanic and Atmospheric Administration's National Hurricane Center|access-date=June 2, 2019|archive-url=https://web.archive.org/web/20190912164011/https://www.nhc.noaa.gov/aboutgloss.shtml#r|archive-date=September 12, 2019|url-status=live}}</ref> Similarly, rapid deepening in tropical cyclones is defined as a minimum sea surface pressure decrease of {{convert|1.75|hPa|inHg|abbr=on}} per hour or {{convert|42|hPa|inHg|abbr=on}} within a 24-hour period; explosive deepening occurs when the surface pressure decreases by {{convert|2.5|hPa|inHg|abbr=on}} per hour for at least 12 hours or {{convert|5|hPa|inHg|abbr=on}} per hour for at least 6 hours.<ref>{{cite journal |last1=Oropeza |first1=Fernando |last2=Raga |first2=Graciela B. |title=Rapid deepening of tropical cyclones in the northeastern Tropical Pacific: The relationship with oceanic eddies |journal=Atmósfera |date=January 2015 |volume=28 |issue=1 |pages=27–42 |doi=10.1016/S0187-6236(15)72157-0 |bibcode=2015Atmo...28...27O |doi-access=free }}</ref> For rapid intensification to occur, several conditions must be in place. Water temperatures must be extremely high (near or above {{Convert|30|C|F}}), and water of this temperature must be sufficiently deep such that waves do not upwell cooler waters to the surface. On the other hand, [[Earth:Tropical Cyclone Heat Potential|Tropical Cyclone Heat Potential]] is one of such non-conventional subsurface [[Physics:Oceanography|oceanographic]] parameters influencing the [[Physics:Cyclone|cyclone]] intensity. [[Physics:Wind shear|Wind shear]] must be low; when wind shear is high, the [[Astronomy:Convection#Atmospheric convection|convection]] and circulation in the cyclone will be disrupted. Usually, an [[Earth:Anticyclone|anticyclone]] in the upper layers of the [[Earth:Troposphere|troposphere]] above the storm must be present as well—for extremely low surface pressures to develop, air must be rising very rapidly in the eyewall of the storm, and an upper-level anticyclone helps channel this air away from the cyclone efficiently.<ref name="Energetics">{{cite web|author=Diana Engle|title=Hurricane Structure and Energetics|publisher=Data Discovery Hurricane Science Center|access-date=October 26, 2008|url=http://www.newmediastudio.org/DataDiscovery/Hurr_ED_Center/Hurr_Structure_Energetics/Hurr_Struct.html|archive-url=https://web.archive.org/web/20080527094650/http://www.newmediastudio.org/DataDiscovery/Hurr_ED_Center/Hurr_Structure_Energetics/Hurr_Struct.html|archive-date=May 27, 2008}}</ref> However, some cyclones such as Hurricane Epsilon have rapidly intensified despite relatively unfavorable conditions.<ref>{{cite web |author1=Brad Reinhart |author2=Daniel Brown |date=October 21, 2020 |title=Hurricane Epsilon Discussion Number 12 |url=https://www.nhc.noaa.gov/archive/2020/al27/al272020.discus.012.shtml |url-status=live |archive-url=https://web.archive.org/web/20210321030619/https://www.nhc.noaa.gov/archive/2020/al27/al272020.discus.012.shtml |archive-date=March 21, 2021 |access-date=February 4, 2021 |website=nhc.noaa.gov |publisher=National Hurricane Center |location=Miami, Florida}}</ref><ref>{{cite news |last=Cappucci |first=Matthew |date=October 21, 2020 |title=Epsilon shatters records as it rapidly intensifies into major hurricane near Bermuda |newspaper={{wipe|The Washington Post}} |url=https://www.washingtonpost.com/weather/2020/10/21/hurricane-epsilon-bermuda-record/ |url-status=live |access-date=February 4, 2021 |archive-url=https://web.archive.org/web/20201210231234/https://www.washingtonpost.com/weather/2020/10/21/hurricane-epsilon-bermuda-record/ |archive-date=December 10, 2020}}</ref>

===Dissipation===
[[File:Paulette 2020-09-10 1200Z.png|thumb|Hurricane Paulette, in 2020, is an example of a sheared tropical cyclone, with deep convection slightly removed from the center of the system.|alt=Satellite image of a cyclone where the thickest clouds are displaced from the central vortex]]
There are a number of ways a tropical cyclone can weaken, dissipate, or lose its tropical characteristics. These include making landfall, moving over cooler water, encountering dry air, or interacting with other weather systems; however, once a system has dissipated or lost its tropical characteristics, its remnants could regenerate a tropical cyclone if environmental conditions become favorable.<ref name="HurricaneGraveyard">{{cite web |last1=Lam |first1=Linda |date=September 4, 2019 |title=Why the Eastern Caribbean Sea Can Be a 'Hurricane Graveyard' |url=https://weather.com/safety/hurricane/news/2019-08-27-caribbean-sea-graveyard-tropical-storms-hurricanes-hostile |url-status=live |archive-url=https://web.archive.org/web/20210704114314/https://weather.com/safety/hurricane/news/2019-08-27-caribbean-sea-graveyard-tropical-storms-hurricanes-hostile |archive-date=July 4, 2021 |access-date=April 6, 2021 |website=[[Company:The Weather Channel|The Weather Channel]] |publisher=TWC Product and Technology}}</ref><ref name="Sadler and Kilonsky 1977">{{cite report |url=https://apps.dtic.mil/sti/pdfs/ADA046589.pdf |title=The Regeneration of South China Sea Tropical Cyclones in the Bay of Bengal |last1=Sadler |first1=James C. |last2=Kilonsky |first2=Bernard J. |date=May 1977 |publisher=Naval Environmental Prediction Research Facility |location=Monterey, California |access-date=April 6, 2021 |archive-url=https://web.archive.org/web/20210622094956/https://apps.dtic.mil/sti/pdfs/ADA046589.pdf |archive-date=June 22, 2021 |url-status=live |via=Defense Technical Information Center}}</ref>

A tropical cyclone can dissipate when it moves over waters significantly cooler than {{convert|26.5|C|F}}. This will deprive the storm of such tropical characteristics as a warm core with thunderstorms near the center, so that it becomes a remnant [[Physics:Low-pressure area|low-pressure area]]. Remnant systems may persist for several days before losing their identity. This dissipation mechanism is most common in the eastern North Pacific. Weakening or dissipation can also occur if a storm experiences vertical wind shear which causes the convection and heat engine to move away from the center; this normally ceases the development of a tropical cyclone.<ref name="EAM">{{cite book |author=Chang, Chih-Pei |url=https://books.google.com/books?id=N8QYOdqGdgkC&pg=PA484 |title=East Asian Monsoon |publisher=[[Company:World Scientific|World Scientific]] |year=2004 |isbn=978-981-238-769-1 |oclc=61353183 |access-date=November 22, 2020 |archive-url=https://web.archive.org/web/20210814124330/https://books.google.com/books?id=N8QYOdqGdgkC&pg=PA484 |archive-date=August 14, 2021 |url-status=live}}</ref> In addition, its interaction with the main belt of the [[Earth:Westerlies|Westerlies]], by means of merging with a nearby frontal zone, can cause tropical cyclones to evolve into extratropical cyclones. This transition can take 1–3&nbsp;days.<ref name="JWTC intensity">{{cite web|url=http://www.nrlmry.navy.mil/~chu/chap6/se300.htm|author=United States Naval Research Laboratory|work=Tropical Cyclone Forecasters' Reference Guide|title=Tropical Cyclone Intensity Terminology|access-date=November 30, 2006|date=September 23, 1999|archive-url=https://web.archive.org/web/20120712084743/http://www.nrlmry.navy.mil/~chu/chap6/se300.htm|archive-date=July 12, 2012|url-status=live}}</ref>

Should a tropical cyclone make landfall or pass over an island, its circulation could start to break down, especially if it encounters mountainous terrain.<ref name="LifeCycle">{{cite web|url=http://www.aoml.noaa.gov/hrd/tcfaq/C2.html |title=Anatomy and Life Cycle of a Storm: What Is the Life Cycle of a Hurricane and How Do They Move?|year=2020|publisher=United States Hurricane Research Division|access-date=February 17, 2021|url-status=live|archive-url=https://web.archive.org/web/20210217090448/https://www.aoml.noaa.gov/hrd-faq/|archive-date=February 17, 2021}}</ref> When a system makes landfall on a large landmass, it is cut off from its supply of warm moist maritime air and starts to draw in dry continental air.<ref name="LifeCycle"/> This, combined with the increased friction over land areas, leads to the weakening and dissipation of the tropical cyclone.<ref name="LifeCycle"/> Over a mountainous terrain, a system can quickly weaken; however, over flat areas, it may endure for two to three days before circulation breaks down and dissipates.<ref name="LifeCycle"/>

Over the years, there have been a number of techniques considered to try to artificially modify tropical cyclones.<ref name="Stop">{{cite web|url=http://www.aoml.noaa.gov/hrd/tcfaq/C2.html |title=Attempts to Stop a Hurricane in its Track: What Else has been Considered to Stop a Hurricane?|year=2020|publisher=United States Hurricane Research Division|access-date=February 17, 2021|url-status=live|archive-url=https://web.archive.org/web/20210217090448/https://www.aoml.noaa.gov/hrd-faq/|archive-date=February 17, 2021}}</ref> These techniques have included using [[Engineering:Nuclear weapon|nuclear weapons]], cooling the ocean with icebergs, blowing the storm away from land with giant fans, and seeding selected storms with dry ice or [[Chemistry:Silver iodide|silver iodide]].<ref name="Stop"/> These techniques, however, fail to appreciate the duration, intensity, power or size of tropical cyclones.<ref name="Stop"/>

===Methods for assessing intensity===
A variety of methods or techniques, including surface, satellite, and aerial, are used to assess the intensity of a tropical cyclone. Reconnaissance aircraft fly around and through tropical cyclones, outfitted with specialized instruments, to collect information that can be used to ascertain the winds and pressure of a system.<ref name="Global Guide 2017"/> Tropical cyclones possess winds of different speeds at different heights. Winds recorded at flight level can be converted to find the wind speeds at the surface.<ref>{{cite journal |last1=Knaff |first1=John |last2=Longmore |first2=Scott |last3=DeMaria |first3=Robert |last4=Molenar |first4=Debra |date=February 1, 2015 |title=Improved Tropical-Cyclone Flight-Level Wind Estimates Using RoutineInfrared Satellite Reconnaissance |url=https://journals.ametsoc.org/view/journals/apme/54/2/jamc-d-14-0112.1.xml?tab_body=pdf |url-status=live |journal=[[Earth:Journal of Applied Meteorology and Climatology|Journal of Applied Meteorology and Climatology]] |publisher=American Meteorological Society |volume=54 |issue=2 |page=464 |bibcode=2015JApMC..54..463K |doi=10.1175/JAMC-D-14-0112.1 |s2cid=17309033 |archive-url=https://web.archive.org/web/20210424010841/https://journals.ametsoc.org/view/journals/apme/54/2/jamc-d-14-0112.1.xml?tab_body=pdf |archive-date=April 24, 2021 |access-date=April 23, 2021|doi-access=free }}</ref> Surface observations, such as ship reports, land stations, [[Earth:Mesonet|mesonet]]s, coastal stations, and buoys, can provide information on a tropical cyclone's intensity or the direction it is traveling.<ref name="Global Guide 2017"/> Wind-pressure relationships (WPRs) are used as a way to determine the pressure of a storm based on its wind speed. Several different methods and equations have been proposed to calculate WPRs.<ref>{{cite journal |last1=Knaff |first1=John |last2=Reed |first2=Kevin |last3=Chavas |first3=Daniel |date=November 8, 2017 |title=Physical understanding of the tropical cyclone wind-pressure relationship |journal=Nature Communications |volume=8 |issue=1360 |page=1360 |bibcode=2017NatCo...8.1360C |doi=10.1038/s41467-017-01546-9 |pmc=5678138 |pmid=29118342}}</ref><ref name="WPRs">{{cite journal |last1=Kueh |first1=Mien-Tze |date=May 16, 2012 |title=Multiformity of the tropical cyclone wind–pressure relationship in the western North Pacific: discrepancies among four best-track archives |journal=Environmental Research Letters |publisher=[[Company:IOP Publishing|IOP Publishing]] |volume=7 |issue=2 |pages=2–6 |bibcode=2012ERL.....7b4015K |doi=10.1088/1748-9326/7/2/024015 |doi-access=free}}</ref> Tropical cyclones agencies each use their own, fixed WPR, which can result in inaccuracies between agencies that are issuing estimates on the same system.<ref name="WPRs"/> The ASCAT is a [[Scatterometer|scatterometer]] used by the [[Engineering:MetOp|MetOp]] satellites to map the wind field vectors of tropical cyclones.<ref name="Global Guide 2017"/> The SMAP uses an L-band [[Physics:Radiometer|radiometer]] channel to determine the wind speeds of tropical cyclones at the ocean surface, and has been shown to be reliable at higher intensities and under heavy rainfall conditions, unlike scatterometer-based and other radiometer-based instruments.<ref>{{cite journal |last1=Meissner |first1=Thomas |last2=Ricciardulli |first2=L. |last3=Wentz |first3=F. |last4=Sampson |first4=C. |title=Intensity and Size of Strong Tropical Cyclones in 2017 from NASA's SMAP L-Band Radiometer |url=https://ams.confex.com/ams/33HURRICANE/webprogram/Paper339308.html |website=American Meteorological Society |access-date=April 21, 2021 |date=April 18, 2018 |archive-date=April 21, 2021 |archive-url=https://web.archive.org/web/20210421211403/https://ams.confex.com/ams/33HURRICANE/webprogram/Paper339308.html |url-status=live }}</ref>

The [[Earth:Dvorak technique|Dvorak technique]] plays a large role in both the classification of a tropical cyclone and the determination of its intensity. Used in warning centers, the method was developed by Vernon Dvorak in the 1970s, and uses both visible and infrared satellite imagery in the assessment of tropical cyclone intensity. The Dvorak technique uses a scale of "T-numbers", scaling in increments of 0.5 from T1.0 to T8.0. Each T-number has an intensity assigned to it, with larger T-numbers indicating a stronger system. Tropical cyclones are assessed by forecasters according to an array of patterns, including [[Earth:Rainband|curved banding features]], shear, central dense overcast, and eye, in order to determine the T-number and thus assess the intensity of the storm.<ref>{{cite book |last1=DeMaria |first1=Mark |last2=Knaff |first2=John |last3=Zehr |first3=Raymond |title=Satellite-based Applications on Climate Change |date=2013 |publisher=Springer |pages=152–154 |url=https://rammb.cira.colostate.edu/resources/docs/DeMaria_Knaff_StarBook2013.pdf |access-date=April 21, 2021 |archive-date=April 22, 2021 |archive-url=https://web.archive.org/web/20210422013741/https://rammb.cira.colostate.edu/resources/docs/DeMaria_Knaff_StarBook2013.pdf |url-status=live }}</ref> The [[Organization:Cooperative Institute for Meteorological Satellite Studies|Cooperative Institute for Meteorological Satellite Studies]] works to develop and improve automated satellite methods, such as the Advanced Dvorak Technique (ADT) and SATCON. The ADT, used by a large number of forecasting centers, uses infrared geostationary satellite imagery and an algorithm based upon the Dvorak technique to assess the intensity of tropical cyclones. The ADT has a number of differences from the conventional Dvorak technique, including changes to intensity constraint rules and the usage of microwave imagery to base a system's intensity upon its internal structure, which prevents the intensity from leveling off before an eye emerges in infrared imagery.<ref>{{cite journal |last1=Olander |first1=Timothy |last2=Veldan |first2=Christopher |title=The Advanced Dvorak Technique (ADT) for Estimating Tropical Cyclone Intensity: Update and New Capabilities |journal=American Meteorological Society |date=August 1, 2019 |volume=34 |issue=4 |pages=905–907 |doi=10.1175/WAF-D-19-0007.1 |bibcode=2019WtFor..34..905O |url=https://journals.ametsoc.org/view/journals/wefo/34/4/waf-d-19-0007_1.xml?tab_body=pdf |access-date=April 21, 2021 |doi-access=free |archive-date=April 21, 2021 |archive-url=https://web.archive.org/web/20210421201604/https://journals.ametsoc.org/view/journals/wefo/34/4/waf-d-19-0007_1.xml?tab_body=pdf |url-status=live }}</ref> The SATCON weights estimates from various satellite-based systems and [[Engineering:Advanced microwave sounding unit|microwave sounders]], accounting for the strengths and flaws in each individual estimate, to produce a consensus estimate of a tropical cyclone's intensity which can be more reliable than the Dvorak technique at times.<ref>{{cite journal |last1=Velden |first1=Christopher |last2=Herndon |first2=Derrick |title=A Consensus Approach for Estimating Tropical Cyclone Intensity from Meteorological Satellites: SATCON |journal=American Meteorological Society |date=July 21, 2020 |volume=35 |issue=4 |pages=1645–1650 |doi=10.1175/WAF-D-20-0015.1 |bibcode=2020WtFor..35.1645V |url=https://journals.ametsoc.org/view/journals/wefo/35/4/wafD200015.xml?tab_body=pdf |access-date=April 21, 2021 |doi-access=free |archive-date=April 21, 2021 |archive-url=https://web.archive.org/web/20210421204850/https://journals.ametsoc.org/view/journals/wefo/35/4/wafD200015.xml?tab_body=pdf |url-status=live }}</ref><ref>{{cite journal |last1=Chen |first1=Buo-Fu |last2=Chen |first2=Boyo |last3=Lin |first3=Hsuan-Tien |last4=Elsberry |first4=Russell |title=Estimating tropical cyclone intensity by satellite imagery utilizing convolutional neural networks |journal=American Meteorological Society |date=April 2019 |volume=34 |issue=2 |page=448 |doi=10.1175/WAF-D-18-0136.1 |bibcode=2019WtFor..34..447C |url=https://opensky.ucar.edu/islandora/object/articles%3A22481/datastream/PDF |access-date=April 21, 2021 |doi-access=free |archive-date=April 21, 2021 |archive-url=https://web.archive.org/web/20210421204900/https://opensky.ucar.edu/islandora/object/articles:22481/datastream/PDF |url-status=live }}</ref>

===Intensity metrics===
Multiple intensity metrics are used, including [[Earth:Accumulated cyclone energy|accumulated cyclone energy]] (ACE), the Hurricane Surge Index, the [[Earth:Hurricane Severity Index|Hurricane Severity Index]], the Power Dissipation Index (PDI), and integrated kinetic energy (IKE). ACE is a metric of the total energy a system has exerted over its lifespan. ACE is calculated by summing the squares of a cyclone's sustained wind speed, every six hours as long as the system is at or above tropical storm intensity and either tropical or subtropical.<ref>{{cite journal|author1=Davis, Kyle |author2=Zeng, Xubin |title=Seasonal Prediction of North Atlantic Accumulated Cyclone Energy and Major Hurricane Activity |journal=Weather and Forecasting |date=February 1, 2019 |volume=34 |issue=1 |pages=221–232 |doi=10.1175/WAF-D-18-0125.1 |publisher=American Meteorological Society|bibcode=2019WtFor..34..221D |hdl=10150/632896 |s2cid=128293725 |doi-access=free |hdl-access=free }}</ref> The calculation of the PDI is similar in nature to ACE, with the major difference being that wind speeds are cubed rather than squared.<ref>{{cite journal|author1=Villarini, Gabriele |author2=Vecchi, Gabriel A |title=North Atlantic Power Dissipation Index (PDI) and Accumulated Cyclone Energy (ACE): Statistical Modeling and Sensitivity to Sea Surface Temperature Changes |journal=Journal of Climate |date=January 15, 2012 |volume=25 |issue=2 |pages=625–637 |doi=10.1175/JCLI-D-11-00146.1 |publisher=American Meteorological Society|bibcode=2012JCli...25..625V |s2cid=129106927 }}</ref> The Hurricane Surge Index is a metric of the potential damage a storm may inflict via storm surge. It is calculated by squaring the dividend of the storm's wind speed and a climatological value ({{cvt|33|m/s|mph|disp=or}}), and then multiplying that quantity by the dividend of the radius of hurricane-force winds and its climatological value ({{cvt|96.6|km|mi|disp=or}}). This can be represented in equation form as:
:<math>\left(\frac{v}{33\ m/s}\right)^2\times\left(\frac{r}{96.6\ km}\right)\,</math>
where v is the storm's wind speed and r is the radius of hurricane-force winds.<ref>{{cite journal |last1=Islam |first1=Md. Rezuanal |last2=Lee |first2=Chia-Ying |last3=Mandli |first3=Kyle T. |last4=Takagi |first4=Hiroshi |date=August 18, 2021 |title=A new tropical cyclone surge index incorporating the effects of coastal geometry, bathymetry and storm information |journal=Scientific Reports |volume=11 |issue=1 |page=16747 |bibcode=2021NatSR..1116747I |doi=10.1038/s41598-021-95825-7 |pmc=8373937 |pmid=34408207 |doi-access=free}}</ref> The Hurricane Severity Index is a scale that can assign up to 50 points to a system; up to 25 points come from intensity, while the other 25 come from the size of the storm's wind field.<ref name="IKE + HSI">{{cite journal |last1=Rezapour |first1=Mehdi |last2=Baldock |first2=Tom E. |title=Classification of Hurricane Hazards: The Importance of Rainfall |journal=Weather and Forecasting |date=December 1, 2014 |volume=29 |issue=6 |pages=1319–1331 |doi=10.1175/WAF-D-14-00014.1 |publisher=American Meteorological Society|bibcode=2014WtFor..29.1319R |s2cid=121762550 |doi-access=free }}</ref> The IKE model measures the destructive capability of a tropical cyclone via winds, waves, and surge. It is calculated as:
:<math>\int_{Vol} \frac{1}{2}pu^2d_{v}\,</math>
where p is the density of air, u is a sustained surface wind speed value, and d{{sub|v}} is the [[Volume element|volume element]].<ref name="IKE + HSI"/><ref>{{cite book |author1=Kozar, Michael E|author2=Misra, Vasubandhu |chapter=Integrated Kinetic Energy in North Atlantic Tropical Cyclones: Climatology, Analysis, and Seasonal Applications |title=Hurricane Risk |date=February 16, 2019 |volume=1 |publisher=Springer |isbn=978-3-030-02402-4 |pages=43–69 |doi=10.1007/978-3-030-02402-4_3|s2cid=133717045 }}</ref>

== Classification and naming ==
===Classification===
{{Main|Earth:Tropical cyclone scales}}
[[File:Maria, Bopha and Saomai 2006-08-07 0435Z.jpg|thumb|upright=0.95|Three tropical cyclones of the 2006 Pacific typhoon season at different stages of development. The weakest (left) demonstrates only the most basic circular shape. A stronger storm (top right) demonstrates spiral banding and increased centralization, while the strongest (lower right) has developed an eye.|alt=Satellite image of three simultaneous tropical cyclones]]

Around the world, tropical cyclones are classified in different ways, based on the location ([[Earth:Tropical cyclone basins|tropical cyclone basins]]), the structure of the system and its intensity. For example, within the Northern Atlantic and Eastern Pacific basins, a tropical cyclone with wind speeds of over {{convert|65|kn|km/h mph|lk=in|abbr=on}} is called a '''hurricane''', while it is called a '''typhoon''' or a severe cyclonic storm within the Western Pacific or North Indian oceans.<ref name="ATL/EPAC TCOP">{{cite report |url=http://www.wmo.int/pages/prog/www/tcp/documents/RA-IV-HC-41-OperationalPlan_en_final.pdf |title=Regional Association IV Hurricane Operational Plan 2019 |author=RA IV Hurricane Committee |publisher=World Meteorological Organization |access-date=July 2, 2019 |archive-url=https://web.archive.org/web/20190702225644/http://www.wmo.int/pages/prog/www/tcp/documents/RA-IV-HC-41-OperationalPlan_en_final.pdf |archive-date=July 2, 2019 |url-status=live}}</ref><ref name="WPAC TCOP" /><ref name="NIO TCOP">{{cite report |url=http://www.wmo.int/pages/prog/www/tcp/documents/PTC-OperationalPlan_TCP-21_Edition2018.pdf |title=Tropical Cyclone Operational Plan for the Bay of Bengal and the Arabian Sea 2018 |author=WMO/ESCAP Panel on Tropical Cyclones |date=November 2, 2018 |publisher=World Meteorological Organization |pages=11–12 |access-date=July 2, 2019 |archive-url=https://web.archive.org/web/20190702225646/http://www.wmo.int/pages/prog/www/tcp/documents/PTC-OperationalPlan_TCP-21_Edition2018.pdf |archive-date=July 2, 2019 |url-status=live |type=Report No. TCP-21}}</ref> When a hurricane passes west across the International Dateline in the Northern Hemisphere, it becomes known as a typhoon. This happened in 2014 for Hurricane Genevieve, which became Typhoon Genevieve.<ref>[https://abc7news.com/cyclones-typhoons-hurricane-accuweather/1370370/#:~:text=The%20only%20time%20when%20a,line%20and%20became%20Typhoon%20Genevieve. "Learn the difference between hurricanes, cyclones and typhoons"], ABC, Inc., KGO-TV San Francisco, Channel 7 News. Retrieved May 25, 2023.</ref> Within the Southern Hemisphere, it is either called a hurricane, tropical cyclone or a severe tropical cyclone, depending on if it is located within the South Atlantic, South-West Indian Ocean, Australian region or the South Pacific Ocean.<ref name="SWIO TCOP" /><ref name="SPAC TCOP" /> The descriptors for tropical cyclones with wind speeds below {{cvt|65|kn|km/h mph|round=5}} also vary by tropical cyclone basin and may be further subdivided into categories such as "tropical storm", "cyclonic storm", "tropical depression", or "deep depression".<ref name="WPAC TCOP" /><ref name="NIO TCOP" /><ref name="ATL/EPAC TCOP" />

===Naming===

The practice of using given names to identify tropical cyclones dates back to the late 1800s and early 1900s and gradually superseded the existing system—simply naming cyclones based on what they hit.<ref name="Whats in a name?">{{cite journal |author=Smith, Ray |year=1990 |title=What's in a Name? |url=http://www.metsoc.org.nz/system/files/journals/10/1/1990_101_24-26_rsmith.pdf |url-status=dead |journal=Weather and Climate |publisher=The Meteorological Society of New Zealand |volume=10 |issue=1 |pages=24–26 |doi=10.2307/44279572 |jstor=44279572 |archive-url=https://web.archive.org/web/20141129194207/http://www.metsoc.org.nz/system/files/journals/10/1/1990_101_24-26_rsmith.pdf |archive-date=November 29, 2014 |access-date=August 25, 2014 |s2cid=201717866}}</ref><ref name="Mahina">{{cite web |author=Dorst, Neal M |date=October 23, 2012 |title=They Called the Wind Mahina: The History of Naming Cyclones |url=ftp://ftp.aoml.noaa.gov/hrd/pub/dorst/Mahina.pptx |work=Hurricane Research Division, [[Organization:Atlantic Oceanographic and Meteorological Laboratory|Atlantic Oceanographic and Meteorological Laboratory]] |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] |page=Slides 8–72}}</ref> The system currently used provides positive identification of severe weather systems in a brief form, that is readily understood and recognized by the public.<ref name="Whats in a name?" /><ref name="Mahina" /> The credit for the first usage of personal names for weather systems is generally given to the Queensland Government Meteorologist Clement Wragge who named systems between 1887 and 1907.<ref name="Whats in a name?" /><ref name="Mahina" /> This system of naming weather systems subsequently fell into disuse for several years after Wragge retired, until it was revived in the latter part of [[Social:World War II|World War II]] for the Western Pacific.<ref name="Whats in a name?" /><ref name="Mahina" /> Formal naming schemes have subsequently been introduced for the North and South Atlantic, Eastern, Central, Western and Southern Pacific basins as well as the Australian region and Indian Ocean.<ref name="Mahina" />

At present, tropical cyclones are officially named by one of twelve meteorological services and retain their names throughout their lifetimes to provide ease of communication between forecasters and the general public regarding forecasts, watches, and warnings.<ref name="Whats in a name?" /> Since the systems can last a week or longer and more than one can be occurring in the same basin at the same time, the names are thought to reduce the confusion about what storm is being described.<ref name="Whats in a name?" /> Names are assigned in order from predetermined lists with one, three, or ten-minute sustained wind speeds of more than {{convert|65|km/h|mph|round=5|abbr=on}} depending on which basin it originates.<ref name="ATL/EPAC TCOP" /><ref name="NIO TCOP" /><ref name="SWIO TCOP" /> However, standards vary from basin to basin with some tropical depressions named in the Western Pacific, while tropical cyclones have to have a significant amount of gale-force winds occurring around the center before they are named within the [[Earth:Southern Hemisphere|Southern Hemisphere]].<ref name="SWIO TCOP" /><ref name="SPAC TCOP" /> The names of significant tropical cyclones in the North Atlantic Ocean, Pacific Ocean, and Australian region are retired from the naming lists and replaced with another name.<ref name="ATL/EPAC TCOP" /><ref name="WPAC TCOP" /><ref name="SPAC TCOP" /> Tropical cyclones that develop around the world are assigned an identification code consisting of a two-digit number and suffix letter by the warning centers that monitor them.<ref name="SPAC TCOP" /><ref name="OFCM NHOP">{{cite report |url=http://www.ofcm.gov/publications/nhop/FCM-P12-2017.pdf |title=National Hurricane Operations Plan |author=Office of the Federal Coordinator for Meteorological Services and Supporting Research |date=May 2017 |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] |pages=26–28 |access-date=October 14, 2018 |archive-url=https://web.archive.org/web/20181015042240/https://www.ofcm.gov/publications/nhop/FCM-P12-2017.pdf |archive-date=October 15, 2018 |url-status=live}}</ref>

=== Related cyclone types ===
In addition to tropical cyclones, there are two other classes of [[Physics:Cyclone|cyclones]] within the spectrum of cyclone types. These kinds of cyclones, known as extratropical cyclones and subtropical cyclones, can be stages a tropical cyclone passes through during its [[Earth:Tropical cyclogenesis|formation]] or dissipation.<ref name="IWTC5">{{cite web |author=Lander, Mark A. |display-authors=0 |date=August 3, 2003 |title=Fifth International Workshop on Tropical Cyclones |url=http://www.aoml.noaa.gov/hrd/iwtc/Lander4-1.html |url-status=live |archive-url=https://web.archive.org/web/20090509043704/http://www.aoml.noaa.gov/hrd/iwtc/Lander4-1.html |archive-date=May 9, 2009 |access-date=May 6, 2009 |publisher=[[Organization:World Meteorological Organization|World Meteorological Organization]]}}</ref> An ''extratropical cyclone'' is a storm that derives energy from horizontal temperature differences, which are typical in higher latitudes. A tropical cyclone can become extratropical as it moves toward higher latitudes if its energy source changes from heat released by condensation to differences in temperature between air masses; although not as frequently, an extratropical cyclone can transform into a subtropical storm, and from there into a tropical cyclone.<ref name="autogenerated2">{{cite web |author=Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division |title=Frequently Asked Questions: What is an extra-tropical cyclone? |url=http://www.aoml.noaa.gov/hrd/tcfaq/A7.html |url-status=dead |archive-url=https://web.archive.org/web/20070209121005/http://www.aoml.noaa.gov/hrd/tcfaq/A7.html |archive-date=February 9, 2007 |access-date=July 25, 2006 |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]}}</ref> From space, extratropical storms have a characteristic "comma-shaped" cloud pattern.<ref name="L14">{{cite web |date=February 25, 2008 |title=Lesson 14: Background: Synoptic Scale |url=http://profhorn.meteor.wisc.edu/wxwise/satmet/lesson14/Satextracyclone.html |url-status=live |archive-url=https://web.archive.org/web/20090220150352/http://profhorn.meteor.wisc.edu/wxwise/satmet/lesson14/Satextracyclone.html |archive-date=February 20, 2009 |access-date=May 6, 2009 |publisher=[[Organization:University of Wisconsin–Madison|University of Wisconsin–Madison]]}}</ref> Extratropical cyclones can also be dangerous when their low-pressure centers cause powerful winds and high seas.<ref>{{cite web |year=2008 |title=An Overview of Coastal Land Loss: With Emphasis on the Southeastern United States. |url=http://pubs.usgs.gov/of/2003/of03-337/winter.html |url-status=live |archive-url=https://web.archive.org/web/20090212222023/http://pubs.usgs.gov/of/2003/of03-337/winter.html |archive-date=February 12, 2009 |access-date=May 6, 2009 |publisher=United States Geological Survey}}</ref>

A ''subtropical cyclone'' is a [[Earth:Weather|weather]] system that has some characteristics of a tropical cyclone and some characteristics of an extratropical cyclone. They can form in a wide band of latitudes, from the equator to 50°. Although subtropical storms rarely have hurricane-force winds, they may become tropical in nature as their cores warm.<ref name="AOML FAQ A6">{{cite web |author=Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division |title=Frequently Asked Questions: What is a sub-tropical cyclone? |url=http://www.aoml.noaa.gov/hrd/tcfaq/A6.html |url-status=dead |archive-url=https://web.archive.org/web/20111011042947/http://www.aoml.noaa.gov/hrd/tcfaq/A6.html |archive-date=October 11, 2011 |access-date=July 25, 2006 |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]}}</ref>

==Structure==
===Eye and center===
{{main|Physics:Eye (cyclone)}}
[[File:Staring Down Hurricane Florence.jpg|thumb|right|The eye and surrounding clouds of 2018 Hurricane Florence as seen from the International Space Station]]
At the center of a mature tropical cyclone, air sinks rather than rises. For a sufficiently strong storm, air may sink over a layer deep enough to suppress cloud formation, thereby creating a clear "[[Physics:Eye (cyclone)|eye]]". Weather in the eye is normally calm and free of convective clouds, although the sea may be extremely violent.<ref name="JetStream structure">{{cite web|url=http://www.srh.noaa.gov/jetstream/tropics/tc_structure.htm|author=National Weather Service|work=JetStream&nbsp;– An Online School for Weather|publisher=National Oceanic & Atmospheric Administration|title=Tropical Cyclone Structure|access-date=May 7, 2009|date=October 19, 2005|archive-url=https://web.archive.org/web/20131207193757/http://www.srh.noaa.gov/jetstream/tropics/tc_structure.htm|archive-date=December 7, 2013|url-status=live}}</ref> The eye is normally circular and is typically {{convert|30|–|65|km|mi|abbr=on}} in diameter, though eyes as small as {{convert|3|km|mi|abbr=on}} and as large as {{convert|370|km|mi|abbr=on}} have been observed.<ref name="WilmaTCR">{{cite web |last=Pasch |first=Richard J. |author2=Eric S. Blake |author3=Hugh D. Cobb III |author4=David P. Roberts |url=http://www.nhc.noaa.gov/data/tcr/AL252005_Wilma.pdf |title=Tropical Cyclone Report: Hurricane Wilma: 15–25 October 2005 |publisher=[[Earth:National Hurricane Center|National Hurricane Center]] |date=September 28, 2006 |access-date=December 14, 2006 |archive-date=March 4, 2016 |archive-url=https://web.archive.org/web/20160304000300/http://www.nhc.noaa.gov/data/tcr/AL252005_Wilma.pdf |url-status=live }}</ref><ref name="MWR 1996 AHS summary">{{Cite journal| doi = 10.1175/1520-0493(1999)127<1157:TMEAVO>2.0.CO;2| title = The Mean Evolution and Variability of the Asian Summer Monsoon: Comparison of ECMWF and NCEP–NCAR Reanalyses| journal = Monthly Weather Review| volume = 127| issue = 6| pages = 1157–1186| year = 1999| last1 = Annamalai| first1 = H.| last2 = Slingo| first2 = J.M.| last3 = Sperber| first3 = K.R.| last4 = Hodges| first4 = K.| bibcode = 1999MWRv..127.1157A| url = https://digital.library.unt.edu/ark:/67531/metadc793439/| access-date = December 12, 2019| archive-date = August 1, 2020| archive-url = https://web.archive.org/web/20200801195058/https://digital.library.unt.edu/ark:/67531/metadc793439/| url-status = live| doi-access = free}}</ref>

The cloudy outer edge of the eye is called the "eyewall". The eyewall typically expands outward with height, resembling an arena football stadium; this phenomenon is sometimes referred to as the "[[Physics:Eye (cyclone)#Stadium effect|stadium effect]]".<ref name="MWR 1996 AHS summary"/> The eyewall is where the greatest wind speeds are found, air rises most rapidly, clouds reach their highest [[Altitude|altitude]], and precipitation is the heaviest. The heaviest wind damage occurs where a tropical cyclone's eyewall passes over land.<ref name="JetStream structure"/>

In a weaker storm, the eye may be obscured by the [[Earth:Central dense overcast|central dense overcast]], which is the upper-level cirrus shield that is associated with a concentrated area of strong thunderstorm activity near the center of a tropical cyclone.<ref name="CDO AMS">{{cite web|author=American Meteorological Society|url=http://amsglossary.allenpress.com/glossary/browse?s=c&p=19|title=AMS Glossary: C|work=Glossary of Meteorology|access-date=December 14, 2006|publisher=Allen Press|archive-url=https://web.archive.org/web/20110126121255/http://amsglossary.allenpress.com/glossary/browse?s=c&p=19|archive-date=January 26, 2011|url-status=live}}</ref>

The eyewall may vary over time in the form of [[Earth:Eyewall replacement cycle|eyewall replacement cycles]], particularly in intense tropical cyclones. Outer rainbands can organize into an outer ring of thunderstorms that slowly moves inward, which is believed to rob the primary eyewall of moisture and [[Physics:Angular momentum|angular momentum]]. When the primary eyewall weakens, the tropical cyclone weakens temporarily. The outer eyewall eventually replaces the primary one at the end of the cycle, at which time the storm may return to its original intensity.<ref name="AOML FAQ D8">{{cite web|author=Atlantic Oceanographic and Hurricane Research Division |title=Frequently Asked Questions: What are "concentric eyewall cycles" (or "eyewall replacement cycles") and why do they cause a hurricane's maximum winds to weaken? |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] |access-date=December 14, 2006 |url=http://www.aoml.noaa.gov/hrd/tcfaq/D8.html |url-status=dead |archive-url=https://web.archive.org/web/20061206051303/http://www.aoml.noaa.gov/hrd/tcfaq/D8.html |archive-date=December 6, 2006}}</ref>
{{clear}}

===Size===

There are a variety of metrics commonly used to measure storm size. The most common metrics include the radius of maximum wind, the radius of {{Convert|34|kn|m/s km/h mph|adj=on}} wind (i.e. gale force), the radius of outermost closed isobar ([[Earth:Radius of outermost closed isobar|ROCI]]), and the radius of vanishing wind.<ref name="Global">{{cite web|url=http://www.cawcr.gov.au/publications/BMRC_archive/tcguide/ch2/ch2_4.htm |title=Global Guide to Tropical Cyclone Forecasting: chapter 2: Tropical Cyclone Structure |date=May 7, 2009 |publisher=Bureau of Meteorology |access-date=May 6, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20110601213941/http://www.cawcr.gov.au/publications/BMRC_archive/tcguide/ch2/ch2_4.htm |archive-date=June 1, 2011}}</ref><ref name="Chavas Emanuel GRL">{{Cite journal | doi = 10.1029/2010GL044558| title = A QuikSCAT climatology of tropical cyclone size| journal = Geophysical Research Letters| volume = 37| issue = 18| year = 2010| last1 = Chavas | first1 = D.R.| last2 = Emanuel | first2 = K.A. | pages = n/a| bibcode=2010GeoRL..3718816C| hdl = 1721.1/64407| s2cid = 16166641| hdl-access = free}}</ref> An additional metric is the radius at which the cyclone's relative [[Vorticity|vorticity]] field decreases to 1×10<sup>−5</sup> s<sup>−1</sup>.<ref name="MWR 1996 AHS summary"/>
{|class="wikitable" style="float: right; font-size: 92%; margin: 1em 0 1em 1em;"
|-
! colspan=2 style="background: #ccf;" | Size descriptions of tropical cyclones
|-
! ROCI (Diameter) || Type
|-
| Less than 2&nbsp;degrees latitude || Very small/minor
|-
| 2 to 3&nbsp;degrees of latitude || Small
|-
| 3 to 6&nbsp;degrees of latitude || Medium/Average/Normal
|-
| 6 to 8&nbsp;degrees of latitude || Large
|-
| Over 8&nbsp;degrees of latitude || Very large<ref name="JTWCsize">{{cite web|url=http://www.usno.navy.mil/JTWC/frequently-asked-questions-1#tcsize|title=Q: What is the average size of a tropical cyclone?|year=2009|publisher=[[Earth:Joint Typhoon Warning Center|Joint Typhoon Warning Center]]|access-date=May 7, 2009|archive-url=https://web.archive.org/web/20131004062635/http://www.usno.navy.mil/JTWC/frequently-asked-questions-1/#tcsize|archive-date=October 4, 2013|url-status=live}}</ref>
|}
On Earth, tropical cyclones span a large range of sizes, from {{convert|100–2000|km|mi|abbr=on}} as measured by the radius of vanishing wind. They are largest on average in the northwest Pacific Ocean basin and smallest in the northeastern [[Earth:Pacific Ocean|Pacific Ocean]] basin.<ref name="Merrill"/> If the radius of outermost closed isobar is less than two [[Earth:Latitude|degrees of latitude]] ({{convert|222|km|mi|abbr=on}}), then the cyclone is "very small" or a "midget". A radius of 3–6 latitude degrees ({{convert|333|–|670|km|mi|abbr=on}}) is considered "average sized". "Very large" tropical cyclones have a radius of greater than 8&nbsp;degrees ({{convert|888|km|mi|abbr=on}}).<ref name="JTWCsize"/> Observations indicate that size is only weakly correlated to variables such as storm intensity (i.e. maximum wind speed), radius of maximum wind, latitude, and maximum potential intensity.<ref name="Chavas Emanuel GRL" /><ref name="Merrill">{{Cite journal |title=A comparison of Large and Small Tropical cyclones |journal=Monthly Weather Review |volume=112 |issue=7 |pages=1408–1418 |last=Merrill |first=Robert T |year=1984 |doi=10.1175/1520-0493(1984)112<1408:ACOLAS>2.0.CO;2 |bibcode=1984MWRv..112.1408M |hdl=10217/200 |s2cid=123276607 |hdl-access=free }}</ref> Typhoon Tip is the largest cyclone on record, with tropical storm-force winds {{convert|2170|km|mi|abbr=on}} in diameter. The smallest storm on record is Tropical Storm Marco of 2008, which generated tropical storm-force winds only {{convert|37|km|mi|abbr=on}} in diameter.<ref name="FAQ">{{cite web|author=Dorst, Neal |author2=Hurricane Research Division |title=Frequently Asked Questions: Subject: E5) Which are the largest and smallest tropical cyclones on record? |publisher=National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory |url=http://www.aoml.noaa.gov/hrd/tcfaq/E5.html |access-date=June 12, 2013 |date=May 29, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20081222095921/http://www.aoml.noaa.gov/hrd/tcfaq/E5.html |archive-date=December 22, 2008}}</ref>

==Movement==
The movement of a tropical cyclone (i.e. its "track") is typically approximated as the sum of two terms: "steering" by the background environmental wind and "beta drift".<ref name="Holland JAS 1983">{{Cite journal| doi = 10.1175/1520-0469(1983)040<0328:TCMEIP>2.0.CO;2| title = Tropical Cyclone Motion: Environmental Interaction Plus a Beta Effect| journal = Journal of the Atmospheric Sciences| volume = 40| issue = 2| pages = 328–342| year = 1983| last1 = Holland| first1 = G.J.| bibcode = 1983JAtS...40..328H| s2cid = 124178238| doi-access = free}}</ref> Some tropical cyclones can move across large distances, such as Hurricane John, the second longest-lasting tropical cyclone on record, which traveled {{convert|13280|km|mi|abbr=on}}, the longest track of any Northern Hemisphere tropical cyclone, over its 31-day lifespan in 1994.<ref name="john94">{{cite web|author=Dorst, Neal |author2=Hurricane Research Division |title=Subject: E6) Frequently Asked Questions: Which tropical cyclone lasted the longest? |access-date=June 12, 2013 |publisher=National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory |url=http://www.aoml.noaa.gov/hrd/tcfaq/E7.html |date=January 26, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20090506175506/http://www.aoml.noaa.gov/hrd/tcfaq/E7.html |archive-date=May 6, 2009}}</ref><ref name="faqe7">{{cite web|author=Dorst, Neal |author2=Delgado, Sandy |author3=Hurricane Research Division |title=Frequently Asked Questions: Subject: E7) What is the farthest a tropical cyclone has travelled? |access-date=June 12, 2013 |publisher=National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory |url=http://www.aoml.noaa.gov/hrd/tcfaq/E7.html |date=May 20, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20090506175506/http://www.aoml.noaa.gov/hrd/tcfaq/E7.html |archive-date=May 6, 2009}}</ref><ref>{{cite news|url=https://www.washingtonpost.com/weather/2023/03/07/cyclone-freddy-indian-ocean-hurricane/|newspaper=the Washington Post|title=Deadly cyclone Freddy has become Earth's longest-lived tropical storm|date=2023-03-07|access-date=2023-09-27}}</ref>

===Environmental steering===
Environmental steering is the primary influence on the motion of tropical cyclones.<ref name="Galarneau and Davis 2013" /> It represents the movement of the storm due to prevailing winds and other wider environmental conditions, similar to "leaves carried along by a stream".<ref name="AOML FAQ G6">{{cite web|author=Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division|title=Frequently Asked Questions: What determines the movement of tropical cyclones?|publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]|access-date=July 25, 2006|url=http://www.aoml.noaa.gov/hrd/tcfaq/G6.html|archive-url=https://web.archive.org/web/20120716182608/http://www.aoml.noaa.gov/hrd/tcfaq/G6.html|archive-date=July 16, 2012|url-status=live}}</ref>

Physically, the winds, or flow field, in the vicinity of a tropical cyclone may be treated as having two parts: the flow associated with the storm itself, and the large-scale background flow of the environment.<ref name="Galarneau and Davis 2013">{{cite journal |last1=Galarneau |first1=Thomas J. |last2=Davis |first2=Christopher A. |title=Diagnosing Forecast Errors in Tropical Cyclone Motion |journal=Monthly Weather Review |date=February 1, 2013 |volume=141 |issue=2 |pages=405–430 |doi=10.1175/MWR-D-12-00071.1 |publisher=American Meteorological Society|bibcode=2013MWRv..141..405G |s2cid=58921153 |doi-access=free }}</ref> Tropical cyclones can be treated as local maxima of [[Vorticity|vorticity]] suspended within the large-scale background flow of the environment.<ref name="Wu and Emmanuel 1995" /> In this way, tropical cyclone motion may be represented to first-order as [[Advection|advection]] of the storm by the local [[Earth:Environmental flow|environmental flow]].<ref name="Carr and Elsberry 1990">{{cite journal |last1=Carr |first1=L. E. |last2=Elsberry |first2=Russell L. |title=Observational Evidence for Predictions of Tropical Cyclone Propagation Relative to Environmental Steering |journal=Journal of the Atmospheric Sciences |date=February 15, 1990 |volume=47 |issue=4 |pages=542–546 |doi=10.1175/1520-0469(1990)047<0542:OEFPOT>2.0.CO;2 |publisher=American Meteorological Society|bibcode=1990JAtS...47..542C |s2cid=121754290 |doi-access=free }}</ref> This environmental flow is termed the "steering flow" and is the dominant influence on tropical cyclone motion.<ref name="Galarneau and Davis 2013" /> The strength and direction of the steering flow can be approximated as a vertical integration of the winds blowing horizontally in the cyclone's vicinity, weighted by the altitude at which those winds are occurring. Because winds can vary with height, determining the steering flow precisely can be difficult.

The pressure altitude at which the background winds are most correlated with a tropical cyclone's motion is known as the "steering level".<ref name="Wu and Emmanuel 1995">{{cite journal |last1=Wu |first1=Chun-Chieh |last2=Emanuel |first2=Kerry A. |title=Potential vorticity Diagnostics of Hurricane Movement. Part 1: A Case Study of Hurricane Bob (1991) |journal=Monthly Weather Review |date=January 1, 1995 |volume=123 |issue=1 |pages=69–92 |doi=10.1175/1520-0493(1995)123<0069:PVDOHM>2.0.CO;2 |publisher=American Meteorological Society|bibcode=1995MWRv..123...69W |doi-access=free }}</ref> The motion of stronger tropical cyclones is more correlated with the background flow averaged across a thicker portion of [[Earth:Troposphere|troposphere]] compared to weaker tropical cyclones whose motion is more correlated with the background flow averaged across a narrower extent of the lower troposphere.<ref name="Velden and Leslie 1991">{{cite journal |last1=Velden |first1=Christopher S. |last2=Leslie |first2=Lance M. |title=The Basic Relationship between Tropical Cyclone Intensity and the Depth of the Environmental Steering Layer in the Australian Region |journal=Weather and Forecasting |date=June 1, 1991 |volume=6 |issue=2 |pages=244–253 |doi=10.1175/1520-0434(1991)006<0244:TBRBTC>2.0.CO;2 |publisher=American Meteorological Society|bibcode=1991WtFor...6..244V |doi-access=free }}</ref> When wind shear and [[Physics:Latent heat|latent heat]] release is present, tropical cyclones tend to move towards regions where [[Earth:Potential vorticity|potential vorticity]] is increasing most quickly.<ref>{{cite journal |last1=Chan |first1=Johnny C.L. |title=The Physics of Tropical Cyclone Motion |journal=Annual Review of Fluid Mechanics |date=January 2005 |volume=37 |issue=1 |pages=99–128 |doi=10.1146/annurev.fluid.37.061903.175702 |publisher=Annual Reviews|bibcode=2005AnRFM..37...99C }}</ref>

Climatologically, tropical cyclones are steered primarily westward by the east-to-west [[Earth:Trade winds|trade winds]] on the equatorial side of the [[Earth:Subtropical ridge|subtropical ridge]]—a persistent high-pressure area over the world's subtropical oceans.<ref name="AOML FAQ G6"/> In the tropical North Atlantic and Northeast Pacific oceans, the trade winds steer [[Earth:Tropical wave|tropical easterly waves]] westward from the African coast toward the Caribbean Sea, North America, and ultimately into the central Pacific Ocean before the waves dampen out.<ref name="AOML FAQ A4">{{cite web|author=Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division |title=Frequently Asked Questions: What is an easterly wave? |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] |access-date=July 25, 2006 |url=http://www.aoml.noaa.gov/hrd/tcfaq/A4.html |url-status=dead |archive-url=https://web.archive.org/web/20060718105909/http://www.aoml.noaa.gov/hrd/tcfaq/A4.html |archive-date=July 18, 2006}}</ref> These waves are the precursors to many tropical cyclones within this region.<ref name="MWR Avila 1995">{{Cite journal | doi = 10.1175/1520-0493(1995)123<0887:ATSO>2.0.CO;2| title = Atlantic Tropical Systems of 1993| journal = Monthly Weather Review| volume = 123| issue = 3| pages = 887–896| year = 1995| last1 = Avila | first1 = L.A. | last2 = Pasch | first2 = R.J. |bibcode = 1995MWRv..123..887A | doi-access = free}}</ref> In contrast, in the [[Earth:Indian Ocean|Indian Ocean]] and Western Pacific in both hemispheres, tropical [[Earth:Cyclogenesis|cyclogenesis]] is influenced less by tropical easterly waves and more by the seasonal movement of the Intertropical Convergence Zone and the [[Earth:Monsoon trough|monsoon trough]].<ref name=autogenerated1>{{cite web|author=DeCaria, Alex|work=ESCI 344&nbsp;– Tropical Meteorology|publisher=[[Organization:Millersville University of Pennsylvania|Millersville University]]|url=http://snowball.millersville.edu/~adecaria/ESCI344/esci344_lesson05_TC_climatology.html|title = Lesson 5&nbsp;– Tropical Cyclones: Climatology.|year=2005|access-date=February 22, 2008| archive-url = https://web.archive.org/web/20080507051727/http://snowball.millersville.edu/~adecaria/ESCI344/esci344_lesson05_TC_climatology.html| archive-date = May 7, 2008}}</ref> Other weather systems such as mid-latitude [[Astronomy:Trough (meteorology)|trough]]s and broad monsoon gyres can also influence tropical cyclone motion by modifying the steering flow.<ref name="Velden and Leslie 1991" /><ref name="Carr and Elsberry 1995">{{cite journal |last1=Carr |first1=Lester E. |last2=Elsberry |first2=Russell L. |title=Monsoonal Interactions Leading to Sudden Tropical Cyclone Track Changes |journal=Monthly Weather Review |date=February 1, 1995 |volume=123 |issue=2 |pages=265–290 |doi=10.1175/1520-0493(1995)123<0265:MILTST>2.0.CO;2 |publisher=American Meteorological Society|bibcode=1995MWRv..123..265C |doi-access=free }}</ref>

===Beta drift===
In addition to environmental steering, a tropical cyclone will tend to drift poleward and westward, a motion known as "beta drift".<ref name="Wang et al. 1998">{{cite journal |last1=Wang |first1=Bin |last2=Elsberry |first2=Russell L. |last3=Yuqing |first3=Wang |last4=Liguang |first4=Wu |title=Dynamics in Tropical Cyclone Motion: A Review |journal=Chinese Journal of the Atmospheric Sciences |year=1998 |volume=22 |issue=4 |pages=416–434 |url=http://www.soest.hawaii.edu/MET/Faculty/bwang/bw/paper/wang58.pdf |access-date=April 6, 2021 |publisher=Allerton Press |via=University of Hawaii |archive-date=June 17, 2021 |archive-url=https://web.archive.org/web/20210617170921/https://www.soest.hawaii.edu/MET/Faculty/bwang/bw/paper/wang58.pdf |url-status=live }}</ref> This motion is due to the superposition of a vortex, such as a tropical cyclone, onto an environment in which the [[Physics:Coriolis force|Coriolis force]] varies with latitude, such as on a sphere or [[Physics:Beta plane|beta plane]].<ref name="Holland 1983">{{cite journal |last1=Holland |first1=Greg J. |title=Tropical Cyclone Motion: Environmental Interaction Plus a Beta Effect |journal=Journal of the Atmospheric Sciences |date=February 1, 1983 |volume=40 |issue=2 |pages=328–342 |doi=10.1175/1520-0469(1983)040<0328:TCMEIP>2.0.CO;2 |publisher=American Meteorological Society|bibcode=1983JAtS...40..328H |doi-access=free }}</ref> The magnitude of the component of tropical cyclone motion associated with the beta drift ranges between {{convert|1|–|3|m/s|km/h mph|abbr=on}} and tends to be larger for more intense tropical cyclones and at higher latitudes. It is induced indirectly by the storm itself as a result of feedback between the cyclonic flow of the storm and its environment.<ref name="Fiorino and Elsberry 1989">{{cite journal |last1=Fiorino |first1=Michael |last2=Elsberry |first2=Russell L. |title=Some Aspects of Vortex Structure Related to Tropical Cyclone Motion |journal=Journal of the Atmospheric Sciences |date=April 1, 1989 |volume=46 |issue=7 |pages=975–990 |doi=10.1175/1520-0469(1989)046<0975:SAOVSR>2.0.CO;2 |publisher=American Meteorological Society|bibcode=1989JAtS...46..975F |doi-access=free }}</ref><ref name="Wang et al. 1998" />

Physically, the cyclonic circulation of the storm advects environmental air poleward east of center and equatorial west of center. Because air must conserve its [[Absolute angular momentum|angular momentum]], this flow configuration induces a cyclonic gyre equatorward and westward of the storm center and an anticyclonic gyre poleward and eastward of the storm center. The combined flow of these gyres acts to advect the storm slowly poleward and westward. This effect occurs even if there is zero environmental flow.<ref name="Li and Wang 1994">{{cite journal |last1=Li |first1=Xiaofan |last2=Wang |first2=Bin |title=Barotropic Dynamics of the Beta Gyres and Beta Drift |journal=Journal of the Atmospheric Sciences |date=March 1, 1994 |volume=51 |issue=5 |pages=746–756 |doi=10.1175/1520-0469(1994)051<0746:BDOTBG>2.0.CO;2 |publisher=American Meteorological Society|bibcode=1994JAtS...51..746L |doi-access=free }}</ref><ref name="Willoughby 1990">{{cite journal |last1=Willoughby |first1=H. E. |title=Linear Normal Modes of a Moving, Shallow-Water Barotropic Vortex |journal=Journal of the Atmospheric Sciences |date=September 1, 1990 |volume=47 |issue=17 |pages=2141–2148 |doi=10.1175/1520-0469(1990)047<2141:LNMOAM>2.0.CO;2 |publisher=American Meteorological Society|bibcode= 1990JAtS...47.2141W|doi-access=free }}</ref> Due to a direct dependence of the beta drift on angular momentum, the size of a tropical cyclone can affect the influence of beta drift on its motion; beta drift imparts a greater influence on the movement of larger tropical cyclones than that of smaller ones.<ref name="Hill and Lackmann 2009">{{cite journal |last1=Hill |first1=Kevin A. |last2=Lackmann |first2=Gary M. |title=Influence of Environmental Humidity on Tropical Cyclone Size |journal=Monthly Weather Review |date=October 1, 2009 |volume=137 |issue=10 |pages=3294–3315 |doi=10.1175/2009MWR2679.1 |publisher=American Meteorological Society|bibcode=2009MWRv..137.3294H |doi-access=free }}</ref><ref name="Sun et al. 2015">{{cite journal |last1=Sun |first1=Yuan |last2=Zhong |first2=Zhong |last3=Yi |first3=Lan |last4=Li |first4=Tim |last5=Chen |first5=Ming |last6=Wan |first6=Hongchao |last7=Wang |first7=Yuxing |last8=Zhong |first8=Kai |title=Dependence of the relationship between the tropical cyclone track and western Pacific subtropical high intensity on initial storm size: A numerical investigation: SENSITIVITY OF TC AND WPSH TO STORM SIZE |journal=Journal of Geophysical Research: Atmospheres |date=November 27, 2015 |volume=120 |issue=22 |pages=11,451–11,467 |doi=10.1002/2015JD023716 |publisher=John Wiley & Sons|doi-access=free }}</ref>

===Multiple storm interaction===
{{Main|Physics:Fujiwhara effect}}
A third component of motion that occurs relatively infrequently involves the interaction of multiple tropical cyclones. When two cyclones approach one another, their centers will begin orbiting cyclonically about a point between the two systems. Depending on their separation distance and strength, the two vortices may simply orbit around one another, or else may spiral into the center point and merge. When the two vortices are of unequal size, the larger vortex will tend to dominate the interaction, and the smaller vortex will orbit around it. This phenomenon is called the Fujiwhara effect, after Sakuhei Fujiwhara.<ref>{{cite news|url=http://usatoday30.usatoday.com/weather/wfujiwha.htm|title=Fujiwhara effect describes a stormy waltz|access-date=February 21, 2008|work=[[Software:USA Today|USA Today]]|date=November 9, 2007|archive-url=https://web.archive.org/web/20121105134542/http://usatoday30.usatoday.com/weather/wfujiwha.htm|archive-date=November 5, 2012|url-status=live}}</ref>

===Interaction with the mid-latitude westerlies===
[[File:Ioke 2006 track.png|thumb|Storm track of Typhoon Ioke, showing recurvature off the Japanese coast in 2006|alt=Path of a tropical cyclone]]
Though a tropical cyclone typically moves from east to west in the tropics, its track may shift poleward and eastward either as it moves west of the subtropical ridge axis or else if it interacts with the mid-latitude flow, such as the [[Earth:Jet stream|jet stream]] or an extratropical cyclone. This motion, termed "recurvature", commonly occurs near the western edge of the major ocean basins, where the jet stream typically has a poleward component and extratropical cyclones are common.<ref>{{cite web|url=http://www.nrlmry.navy.mil/~chu/chap4/se200.htm|date=April 10, 2007|title=Section 2: Tropical Cyclone Motion Terminology|publisher=United States Naval Research Laboratory|access-date=May 7, 2009|archive-url=https://web.archive.org/web/20120212182753/http://www.nrlmry.navy.mil/~chu/chap4/se200.htm|archive-date=February 12, 2012|url-status=live}}</ref> An example of tropical cyclone recurvature was Typhoon Ioke in 2006.<ref name="CPHC Ioke">{{cite web|url=http://www.prh.noaa.gov/cphc/summaries/2006.php#ioke|title=Hurricane Ioke: 20–27 August 2006|date=May 2007|access-date=June 9, 2007|author=Powell, Jeff|work=2006 Tropical Cyclones Central North Pacific|publisher=[[Earth:Central Pacific Hurricane Center|Central Pacific Hurricane Center]]|display-authors=0|archive-url=https://web.archive.org/web/20160306135254/http://www.prh.noaa.gov/cphc/summaries/2006.php#ioke|archive-date=March 6, 2016|url-status=live}}</ref>

==Effects==

===Natural phenomena caused or worsened by tropical cyclones===
Tropical cyclones out at sea cause large waves, heavy rain, [[Earth:Flood|flood]]s and high winds, disrupting international shipping and, at times, causing shipwrecks.<ref name="18cva">{{cite web|author1=Roth, David|author2=Cobb, Hugh|name-list-style=amp|year=2001|title=Eighteenth Century Virginia Hurricanes|publisher=NOAA|access-date=February 24, 2007|url=http://www.wpc.ncep.noaa.gov/research/roth/va18hur.htm|archive-url=https://web.archive.org/web/20130501032117/http://www.wpc.ncep.noaa.gov/research/roth/va18hur.htm|archive-date=May 1, 2013|url-status=live}}</ref> Tropical cyclones stir up water, leaving a cool wake behind them, which causes the region to be less favorable for subsequent tropical cyclones.<ref name="NASA Cooling"/> On land, strong [[Earth:Wind|wind]]s can damage or destroy vehicles, buildings, bridges, and other outside objects, turning loose debris into deadly flying projectiles. The [[Physics:Storm surge|storm surge]], or the increase in sea level due to the cyclone, is typically the worst effect from landfalling tropical cyclones, historically resulting in 90% of tropical cyclone deaths.<ref name="Shultz Epid Reviews 2005">{{Cite journal | doi = 10.1093/epirev/mxi011| title = Epidemiology of Tropical Cyclones: The Dynamics of Disaster, Disease, and Development| journal = Epidemiologic Reviews| volume = 27| pages = 21–35| year = 2005| last1 = Shultz | first1 = J.M.| last2 = Russell | first2 = J.| last3 = Espinel | first3 = Z. | pmid=15958424| doi-access = free}}</ref> Cyclone Mahina produced the highest storm surge on record, {{convert|13|m|ft|abbr=on}}, at Bathurst Bay, Queensland, {{wipe|Australia}}, in March 1899.<ref>{{cite journal|title=The World Record Storm Surge and the Most Intense Southern Hemisphere Tropical Cyclone: New Evidence and Modeling|first1=Jonathan|last1= Nott|first2=Camilla |last2=Green|first3=Ian |last3=Townsend|first4=Jeffrey|last4= Callaghan|journal=Bulletin of the American Meteorological Society|date=July 9, 2014|issue=95|volume=5|page=757|doi=10.1175/BAMS-D-12-00233.1|bibcode=2014BAMS...95..757N|doi-access=free}}</ref> Other ocean-based hazards that tropical cyclones produce are [[Earth:Rip current|rip current]]s and [[Physics:Undertow (water waves)|undertow]]. These hazards can occur hundreds of kilometers (hundreds of miles) away from the center of a cyclone, even if other weather conditions are favorable.<ref>{{cite journal |last1=Carey |first1=Wendy |last2=Rogers |first2=Spencer |title=Rip Currents — Coordinating Coastal Research, Outreach and Forecast Methodologies to Improve Public Safety |journal=Solutions to Coastal Disasters Conference 2005 |date=April 26, 2012 |pages=285–296 |doi=10.1061/40774(176)29 |url=https://ascelibrary.org/doi/abs/10.1061/40774(176)29 |access-date=May 25, 2022 |publisher=American Society of Civil Engineers |isbn=9780784407745 |archive-date=May 26, 2022 |archive-url=https://web.archive.org/web/20220526171028/https://ascelibrary.org/doi/abs/10.1061/40774%28176%2929 |url-status=live }}</ref><ref>{{cite journal |last1=Rappaport |first1=Edward N. |title=Loss of Life in the United States Associated with Recent Atlantic Tropical Cyclones |journal=Bulletin of the American Meteorological Society |date=September 1, 2000 |volume=81 |issue=9 |pages=2065–2074 |doi=10.1175/1520-0477(2000)081<2065:LOLITU>2.3.CO;2 |url=https://journals.ametsoc.org/view/journals/bams/81/9/1520-0477_2000_081_2065_lolitu_2_3_co_2.xml?tab_body=pdf |access-date=May 25, 2022 |publisher=American Meteorological Society |bibcode=2000BAMS...81.2065R |s2cid=120065630 |archive-date=May 26, 2022 |archive-url=https://web.archive.org/web/20220526171031/https://journals.ametsoc.org/view/journals/bams/81/9/1520-0477_2000_081_2065_lolitu_2_3_co_2.xml?tab_body=pdf |url-status=live |doi-access=free }}</ref>
The broad rotation of a landfalling tropical cyclone, and vertical wind shear at its periphery, spawns [[Earth:List of tropical cyclone-spawned tornadoes|tornadoes]]. Tornadoes can also be spawned as a result of eyewall mesovortices, which persist until landfall.<ref name="AOML FAQ L6">{{cite web|author=Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division |title=Frequently Asked Questions: Are TC tornadoes weaker than midlatitude tornadoes? |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] |access-date=July 25, 2006 |url=http://www.aoml.noaa.gov/hrd/tcfaq/L6.html |url-status=dead |archive-url=https://web.archive.org/web/20090914103006/http://www.aoml.noaa.gov/hrd/tcfaq/L6.html |archive-date=September 14, 2009}}</ref> Hurricane Ivan produced 120 tornadoes, more than any other tropical cyclone.<ref>{{cite web |last1=Grazulis |first1=Thomas P. |last2=Grazulis |first2=Doris |title=Top 25 Tornado-Generating Hurricanes |url=http://www.tornadoproject.com/alltorns/tophurricanes.htm |website=The Tornado Project |publisher=Environmental Films |access-date=November 8, 2021 |location=St. Johnsbury, Vermont |date=February 27, 2018 |archive-date=December 12, 2013 |archive-url=https://web.archive.org/web/20131212032233/http://www.tornadoproject.com/alltorns/tophurricanes.htm |url-status=live }}</ref> Lightning activity is produced within tropical cyclones; this activity is more intense within stronger storms and closer to and within the storm's eyewall.<ref>{{cite journal |last1=Bovalo |first1=C. |last2=Barthe |first2=C. |last3=Yu |first3=N. |last4=Bègue |first4=N. |title=Lightning activity within tropical cyclones in the South West Indian Ocean |journal=Journal of Geophysical Research: Atmospheres |date=July 16, 2014 |volume=119 |issue=13 |pages=8231–8244 |doi=10.1002/2014JD021651 |publisher=AGU |bibcode=2014JGRD..119.8231B |s2cid=56304603 |doi-access=free }}</ref><ref>{{cite journal |last1=Samsury |first1=Christopher E. |last2=Orville |first2=Richard E. |title=Cloud-to-Ground Lightning in Tropical Cyclones: A Study of Hurricanes Hugo (1989) and Jerry (1989) |journal=Monthly Weather Review |date=August 1, 1994 |volume=122 |issue=8 |pages=1887–1896 |doi=10.1175/1520-0493(1994)122<1887:CTGLIT>2.0.CO;2 |publisher=American Meteorological Society |bibcode=1994MWRv..122.1887S |doi-access=free }}</ref> Tropical cyclones can increase the amount of snowfall a region experiences by delivering additional moisture.<ref>{{cite journal |last1=Collier |first1=E. |last2=Sauter |first2=T. |last3=Mölg |first3=T. |last4=Hardy |first4=D. |title=The Influence of Tropical Cyclones on Circulation, Moisture Transport, and Snow Accumulation at Kilimanjaro During the 2006–2007 Season |journal=  Journal of Geophysical Research: Atmospheres|date=June 10, 2019 |volume=124 |issue=13 |pages=6919–6928 |doi=10.1029/2019JD030682 |url=https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JD030682 |access-date=May 25, 2022 |publisher=AGU |bibcode=2019JGRD..124.6919C |s2cid=197581044 }}</ref> Wildfires can be worsened when a nearby storm fans their flames with its strong winds.<ref>{{cite journal |last1=Osborne |first1=Martin |last2=Malavelle |first2=Florent F. |last3=Adam |first3=Mariana |last4=Buxmann |first4=Joelle |last5=Sugier |first5=Jaqueline |last6=Marenco |first6=Franco |title=Saharan dust and biomass burning aerosols during ex-hurricane Ophelia: observations from the new UK lidar and sun-photometer network |journal=Atmospheric Chemistry and Physics |date=March 20, 2019 |volume=19 |issue=6 |pages=3557–3578 |doi=10.5194/acp-19-3557-2019 |url=https://acp.copernicus.org/articles/19/3557/2019/ |access-date=May 25, 2022 |publisher=Copernicus Publications |bibcode=2019ACP....19.3557O |s2cid=208084167 |archive-date=January 24, 2022 |archive-url=https://web.archive.org/web/20220124090205/https://acp.copernicus.org/articles/19/3557/2019/ |url-status=live |doi-access=free |hdl=10871/36358 |hdl-access=free }}</ref><ref>{{cite journal |last1=Moore |first1=Paul |title=An analysis of storm Ophelia which struck Ireland on 16 October 2017 |journal=Weather |date=August 3, 2021 |volume=76 |issue=9 |pages=301–306 |doi=10.1002/wea.3978 |url=https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/wea.3978 |access-date=May 25, 2022 |publisher=Royal Meteorological Society |bibcode=2021Wthr...76..301M |s2cid=238835099 }}</ref>

===Effect on property and human life===
[[File:Hurricane Ike Bolivar Peninsula, TX.jpg|thumb|alt=total collapse of houses, cars and facilities|Aftermath of Hurricane Ike in Bolivar Peninsula, Texas]]
[[File:1980- Cost of billion dollar hurricanes - US - variwide chart - NOAA data.svg|thumb| The number of $1 billion Atlantic hurricanes almost doubled from the 1980s to the 2010s, and inflation-adjusted costs have increased more than elevenfold.<ref name=NYTimes_20221202/> The increases have been attributed to climate change and to greater numbers of people moving to coastal areas.<ref name=NYTimes_20221202>{{cite news |last1=Philbrick |first1=Ian Pasad |last2=Wu |first2=Ashley |title=Population Growth Is Making Hurricanes More Expensive |url=https://www.nytimes.com/2022/12/02/briefing/why-hurricanes-cost-more.html |newspaper=The New York Times |date=2 December 2022 |archive-url=https://web.archive.org/web/20221206130032/https://www.nytimes.com/2022/12/02/briefing/why-hurricanes-cost-more.html |archive-date=6 December 2022 |url-status=live }} Newspaper states data source: NOAA.</ref>]]

Tropical cyclones regularly affect the coastlines of most of [[Astronomy:Earth|Earth]]'s major bodies of water along the [[Earth:Atlantic Ocean|Atlantic]], [[Earth:Pacific Ocean|Pacific]], and [[Earth:Indian Ocean|Indian]] oceans. Tropical cyclones have caused significant destruction and loss of human life, resulting in about 2&nbsp;million deaths since the 19th century.<ref name="red">{{cite journal|url=https://www.who.int/bulletin/volumes/90/2/11-088302/en/|title=Reduced death rates from cyclones in Bangladesh: what more needs to be done?|first1=Ubydul|last1= Haque|first2=Masahiro|last2= Hashizume|first3=Korine N |last3=Kolivras|first4=Hans J |last4=Overgaard|first5=Bivash |last5=Das|first6=Taro |last6=Yamamoto|date=March 16, 2011|access-date=October 12, 2020|journal=Bulletin of the World Health Organization|archive-date=October 5, 2020|archive-url=https://web.archive.org/web/20201005083126/https://www.who.int/bulletin/volumes/90/2/11-088302/en/|url-status=dead}}</ref> Large areas of standing water caused by flooding lead to [[Medicine:Infection|infection]], as well as contributing to [[Medicine:Mosquito-borne disease|mosquito-borne illnesses]]. Crowded evacuees in shelters increase the risk of disease propagation.<ref name="Shultz Epid Reviews 2005"/> Tropical cyclones significantly interrupt infrastructure, leading to [[Engineering:Power outage|power outages]], bridge and road destruction, and the hampering of reconstruction efforts.<ref name="Shultz Epid Reviews 2005"/><ref name="Power failures">{{cite news|date=August 30, 2005 |title=Hurricane Katrina Situation Report #11|publisher=Office of Electricity Delivery and Energy Reliability (OE) United States Department of Energy|access-date=February 24, 2007|url=http://www.oe.netl.doe.gov/docs/katrina/katrina_083005_1600.pdf|archive-url=https://web.archive.org/web/20061108202531/http://www.oe.netl.doe.gov/docs/katrina/katrina_083005_1600.pdf|archive-date=November 8, 2006|url-status=dead}}</ref><ref>{{cite journal |last1=Adam |first1=Christopher |last2=Bevan |first2=David |title=Tropical cyclones and post-disaster reconstruction of public infrastructure in developing countries |journal=Economic Modelling |date=December 2020 |volume=93 |pages=82–99 |doi=10.1016/j.econmod.2020.07.003 |url=https://www.sciencedirect.com/science/article/abs/pii/S0264999319311824 |access-date=May 25, 2022 |s2cid=224926212 }}</ref> Winds and water from storms can damage or destroy homes, buildings, and other manmade structures.<ref>{{cite book |last1=Cuny |first1=Frederick C. |editor1-last=Abrams |editor1-first=Susan |title=Disasters and Development |date=1994 |url=https://oaktrust.library.tamu.edu/bitstream/handle/1969.1/159887/cuny_intertect_000001_49.pdf?sequence=1 |publisher=INTERTECT Press |isbn=0-19-503292-6 |page=45 |access-date=May 25, 2022 |archive-date=May 26, 2022 |archive-url=https://web.archive.org/web/20220526171026/https://oaktrust.library.tamu.edu/bitstream/handle/1969.1/159887/cuny_intertect_000001_49.pdf?sequence=1 |url-status=live }}</ref><ref>{{cite journal |last1=Le Dé |first1=Loïc |last2=Rey |first2=Tony |last3=Leone |first3=Frederic |last4=Gilbert |first4=David |title=Sustainable livelihoods and effectiveness of disaster responses: a case study of tropical cyclone Pam in Vanuatu |journal=Natural Hazards |date=January 16, 2018 |volume=91 |issue=3 |pages=1203–1221 |doi=10.1007/s11069-018-3174-6 |url=https://link.springer.com/article/10.1007/s11069-018-3174-6 |access-date=May 25, 2022 |publisher=Springer |bibcode=2018NatHa..91.1203L |s2cid=133651688 |archive-date=May 26, 2022 |archive-url=https://web.archive.org/web/20220526012645/https://link.springer.com/article/10.1007/s11069-018-3174-6 |url-status=live }}</ref> Tropical cyclones destroy agriculture, kill livestock, and prevent access to marketplaces for both buyers and sellers; both of these result in financial losses.<ref>{{cite journal |last1=Perez |first1=Eddie |last2=Thompson |first2=Paul |title=Natural Hazards: Causes and Effects: Lesson 5—Tropical Cyclones (Hurricanes, Typhoons, Baguios, Cordonazos, Tainos) |journal=Prehospital and Disaster Medicine |date=September 1995 |volume=10 |issue=3 |pages=202–217 |doi=10.1017/S1049023X00042023 |url=https://www.cambridge.org/core/journals/prehospital-and-disaster-medicine/article/abs/natural-hazards-causes-and-effects-lesson-5tropical-cyclones-hurricanes-typhoons-baguios-cordonazos-tainos/82B619E71E1132507E0A856CC713E7AF |publisher=Cambridge University Press |pmid=10155431 |s2cid=36983623 |access-date=May 25, 2022 |archive-date=May 26, 2022 |archive-url=https://web.archive.org/web/20220526171028/https://www.cambridge.org/core/journals/prehospital-and-disaster-medicine/article/abs/natural-hazards-causes-and-effects-lesson-5tropical-cyclones-hurricanes-typhoons-baguios-cordonazos-tainos/82B619E71E1132507E0A856CC713E7AF |url-status=live }}</ref><ref>{{cite journal |last1=Debnath |first1=Ajay |title=Condition of Agricultural Productivity of Gosaba C.D. Block, South24 Parganas, West Bengal, India after Severe Cyclone Aila |journal=International Journal of Scientific and Research Publications |date=July 2013 |volume=3 |issue=7 |pages=97–100 |url=http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.416.3757&rep=rep1&type=pdf#page=98 |citeseerx=10.1.1.416.3757 |access-date=May 25, 2022 |issn=2250-3153 |archive-date=May 26, 2022 |archive-url=https://web.archive.org/web/20220526171026/http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.416.3757&rep=rep1&type=pdf#page=98 |url-status=live }}</ref><ref>{{cite journal |last1=Needham |first1=Hal F. |last2=Keim |first2=Barry D. |last3=Sathiaraj |first3=David |title=A review of tropical cyclone-generated storm surges: Global data sources, observations, and impacts |journal=Reviews of Geophysics |date=May 19, 2015 |volume=53 |issue=2 |pages=545–591 |doi=10.1002/2014RG000477 |publisher=AGU |bibcode=2015RvGeo..53..545N |s2cid=129145744 |doi-access=free }}</ref> Powerful cyclones that make [[Earth:Landfall|landfall]] &ndash; moving from the ocean to over land &ndash; are some of the most powerful, although that is not always the case. An average of 86&nbsp;tropical cyclones of tropical storm intensity form annually worldwide, with 47 reaching hurricane or typhoon strength, and 20 becoming intense tropical cyclones, super typhoons, or major hurricanes (at least of Category 3 intensity).<ref name="Landsea variability table">{{cite web | first1= Chris|last1= Landsea | url = http://www.aoml.noaa.gov/hrd/Landsea/climvari/table.html | title = Climate Variability table&nbsp;— Tropical Cyclones | publisher = [[Organization:Atlantic Oceanographic and Meteorological Laboratory|Atlantic Oceanographic and Meteorological Laboratory]], [[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] | access-date = October 19, 2006 |  archive-date = October 2, 2012 | archive-url = https://web.archive.org/web/20121002045230/http://www.aoml.noaa.gov/hrd/Landsea/climvari/table.html | url-status = live }}</ref>

In [[Earth:Africa|Africa]], tropical cyclones can originate from [[Earth:Tropical wave|tropical wave]]s generated over the Sahara Desert,<ref>{{cite web|first1=Jonathan|last1= Belles|title=Why Tropical Waves Are Important During Hurricane Season|date=August 28, 2018|publisher=Weather.com|access-date=October 2, 2020|url=https://weather.com/storms/hurricane/news/tropical-wave-explainer-tropics-hurricanes|archive-date=October 1, 2020|archive-url=https://web.archive.org/web/20201001221202/https://weather.com/storms/hurricane/news/tropical-wave-explainer-tropics-hurricanes|url-status=live}}</ref> or otherwise strike the [[Place:Horn of Africa|Horn of Africa]] and [[Place:Southern Africa|Southern Africa]].<ref>{{cite news|first1=Matthew |last1=Schwartz|date=November 22, 2020|title=Somalia's Strongest Tropical Cyclone Ever Recorded Could Drop 2 Years' Rain In 2 Days|publisher=NPR|url=https://www.npr.org/2020/11/22/937790467/somalias-strongest-tropical-cyclone-ever-recorded-could-drop-2-years-rain-in-2-d|access-date=November 23, 2020|archive-date=November 23, 2020|archive-url=https://web.archive.org/web/20201123000841/https://www.npr.org/2020/11/22/937790467/somalias-strongest-tropical-cyclone-ever-recorded-could-drop-2-years-rain-in-2-d|url-status=live}}</ref><ref>{{cite journal|title=Projected changes in tropical cyclones over the South West Indian Ocean under different extents of global warming|first1=M. S.|last1= Muthige|first2=J. |last2=Malherbe|first3=F. A. |last3=Englebrecht|first4=S. |last4=Grab|first5=A. |last5=Beraki|first6=T. R. |last6=Maisha|first7=J. |last7=Van der Merwe|journal=Environmental Research Letters|year=2018|volume=13|number=6|page=065019|doi=10.1088/1748-9326/aabc60|bibcode=2018ERL....13f5019M|s2cid=54879038 |doi-access=free}}</ref> Cyclone Idai in March 2019 hit central Mozambique, becoming the deadliest tropical cyclone on record in Africa, with 1,302&nbsp;fatalities, and damage estimated at US$2.2&nbsp;billion.<ref>{{cite web |last1=Masters |first1=Jeff |title=Africa's Hurricane Katrina: Tropical Cyclone Idai Causes an Extreme Catastrophe |url=https://www.wunderground.com/cat6/Africas-Hurricane-Katrina-Tropical-Cyclone-Idai-Causes-Extreme-Catastrophe |website=Weather Underground |access-date=March 23, 2019 |archive-url=https://web.archive.org/web/20190322214331/https://www.wunderground.com/cat6/Africas-Hurricane-Katrina-Tropical-Cyclone-Idai-Causes-Extreme-Catastrophe |archive-date=March 22, 2019 |url-status=live }}</ref><ref name="Global Catastrophe Recap">{{cite web |title=Global Catastrophe Recap: First Half of 2019 |url=http://thoughtleadership.aonbenfield.com//Documents/20190723-analytics-if-1h-global-report.pdf |publisher=Aon Benfield |access-date=August 12, 2019 |archive-url=https://web.archive.org/web/20190812000713/http://thoughtleadership.aonbenfield.com//Documents/20190723-analytics-if-1h-global-report.pdf |archive-date=August 12, 2019 |url-status=live }}</ref> Réunion island, located east of Southern Africa, experiences some of the wettest tropical cyclones on record. In January 1980, Cyclone Hyacinthe produced 6,083&nbsp;mm (239.5&nbsp;in) of rain over 15&nbsp;days, which was the largest rain total recorded from a tropical cyclone on record.<ref>{{cite web|author=Lyons, Steve|date=February 17, 2010|title=La Reunion Island's Rainfall Dynasty!|url=http://www.weather.com/blog/weather/8_21280.html|url-status=dead|archive-url=https://web.archive.org/web/20140210080403/http://www.weather.com/blog/weather/8_21280.html|archive-date=February 10, 2014|access-date=February 4, 2014|publisher=The Weather Channel}}</ref><ref>{{cite report|url=http://www.meteo.fr/temps/domtom/La_Reunion/meteoreunion2/climatologie/records/rec_RR1.html|title=Précipitations extrêmes|publisher=Meteo France|access-date=April 15, 2013|date=|archive-date=February 21, 2014|archive-url=https://web.archive.org/web/20140221182557/http://www.meteo.fr/temps/domtom/La_Reunion/meteoreunion2/climatologie/records/rec_RR1.html|url-status=live}}</ref><ref>{{cite journal|author=Randall S. Cerveny|display-authors=0|date=June 2007|title=Extreme Weather Records|journal=Bulletin of the American Meteorological Society|volume=88|issue=6|pages=856, 858|bibcode=2007BAMS...88..853C|doi=10.1175/BAMS-88-6-853|doi-access=free}}</ref> In [[Earth:Asia|Asia]], tropical cyclones from the Indian and Pacific oceans regularly affect some of the most populated countries on Earth. In 1970, a cyclone struck Bangladesh, then known as East Pakistan, producing a {{convert|20|ft|m|abbr=on|order=flip}} storm surge that killed at least 300,000&nbsp;people; this made it the deadliest tropical cyclone on record.<ref name="dead">{{cite journal|title=The Deadliest Tropical Cyclone in history?|first1=Neil L. |last1=Frank|first2=S. A. |last2=Husain|date=June 1971|journal=Bulletin of the American Meteorological Society|volume=52|number=6|page=438 |doi=10.1175/1520-0477(1971)052<0438:TDTCIH>2.0.CO;2 |bibcode=1971BAMS...52..438F |s2cid=123589011 |doi-access=free}}</ref> In October 2019, Typhoon Hagibis struck the {{wipe|Japan}}ese island of Honshu and inflicted US$15&nbsp;billion in damage, making it the costliest storm on record in Japan.<ref>{{cite report|url=http://thoughtleadership.aon.com/Documents/20200122-if-natcat2020.pdf|title=Weather, Climate & Catastrophe Insight: 2019 Annual Report|date=January 22, 2020|publisher=AON Benfield|access-date=January 23, 2020|archive-date=January 22, 2020|archive-url=https://web.archive.org/web/20200122154950/http://thoughtleadership.aon.com/Documents/20200122-if-natcat2020.pdf|url-status=live}}</ref> The islands that comprise [[Earth:Oceania|Oceania]], from {{wipe|Australia}} to French Polynesia, are routinely affected by tropical cyclones.<ref>{{cite report|year=2007|page=45|url=http://www.ga.gov.au/webtemp/image_cache/GA10821.pdf|title=Natural hazards in Australia: Identifying risk analysis requirements|first1=Alan |last1=Sharp|first2=Craig |last2=Arthur|author3=Bob Cechet|author4=Mark Edwards|publisher=Geoscience Australia|access-date=October 11, 2020|archive-date=October 31, 2020|archive-url=https://web.archive.org/web/20201031165443/http://www.ga.gov.au/webtemp/image_cache/GA10821.pdf|url-status=live}}</ref><ref>{{cite report |type=Information Sheet: 35 |title=The Climate of Fiji |url=https://www.met.gov.fj/ClimateofFiji.pdf |publisher=Fiji Meteorological Service |access-date=April 29, 2021 |date=April 28, 2006 |archive-date=March 20, 2021 |archive-url=https://web.archive.org/web/20210320081515/https://www.met.gov.fj/ClimateofFiji.pdf |url-status=live }}</ref><ref>{{cite report |title=Republic of Fiji: Third National Communication Report to the United Nations Framework Convention on Climate Change |url=https://unfccc.int/sites/default/files/resource/Fiji_TNC%20Report.pdf |publisher=United Nations Framework Convention on Climate Change |page=62 |date=April 27, 2020 |access-date=August 23, 2021 |archive-date=July 6, 2021 |archive-url=https://web.archive.org/web/20210706131843/https://unfccc.int/sites/default/files/resource/Fiji_TNC%20Report.pdf |url-status=live }}</ref> In Indonesia, a cyclone struck the island of Flores in April 1973, killing 1,653&nbsp;people, making it the deadliest tropical cyclone recorded in the [[Earth:Southern Hemisphere|Southern Hemisphere]].<ref>{{cite news|title=Death toll|agency=Australian Associated Press|url=https://trove.nla.gov.au/newspaper/article/110715084?searchTerm=flores&searchLimits=exactPhrase|newspaper=The Canberra Times|date=June 18, 1973|accessdate=April 22, 2020|archive-date=August 27, 2020|archive-url=https://web.archive.org/web/20200827205214/https://trove.nla.gov.au/newspaper/article/110715084?searchTerm=flores&searchLimits=exactPhrase|url-status=live}}</ref><ref>{{cite web |last1=Masters |first1=Jeff |title=Africa's Hurricane Katrina: Tropical Cyclone Idai Causes an Extreme Catastrophe |url=https://www.wunderground.com/cat6/Africas-Hurricane-Katrina-Tropical-Cyclone-Idai-Causes-Extreme-Catastrophe |website=Weather Underground |accessdate=March 23, 2019 |archive-date=August 4, 2019 |archive-url=https://web.archive.org/web/20190804083147/https://www.wunderground.com/cat6/Africas-Hurricane-Katrina-Tropical-Cyclone-Idai-Causes-Extreme-Catastrophe |url-status=live }}</ref>

[[Earth:Atlantic hurricane|Atlantic]] and Pacific hurricanes regularly affect [[Earth:North America|North America]]. In the {{wipe|United States}}, hurricanes Katrina in 2005 and Harvey in 2017 are the country's costliest ever natural disasters, with monetary damage estimated at US$125&nbsp;billion. Katrina struck Louisiana and largely destroyed the city of New Orleans,<ref>{{Cite web |url=https://www.ncdc.noaa.gov/billions/events/US/1980-2020 |title=Billion-Dollar Weather and Climate Disasters|publisher=National Centers for Environmental Information |access-date=August 23, 2021 |archive-date=August 11, 2021 |archive-url=https://web.archive.org/web/20210811152237/https://www.ncdc.noaa.gov/billions/events/US/1980-2020 |url-status=live }}</ref><ref name="Harvey TCR">{{Cite report |url=https://www.nhc.noaa.gov/data/tcr/AL092017_Harvey.pdf |first1=Eric S.|last1=Blake|first2=David A.|last2=Zelensky|title=Tropical Cyclone Report: Hurricane Harvey|access-date=August 23, 2021 |archive-date=January 26, 2018 |archive-url=https://web.archive.org/web/20180126083538/https://www.nhc.noaa.gov/data/tcr/AL092017_Harvey.pdf |publisher=National Hurricane Center|url-status=live }}</ref> while Harvey caused significant flooding in southeastern {{wipe|Texas}} after it dropped {{convert|60.58|in|mm|abbr=on}} of rainfall; this was the highest rainfall total on record in the country.<ref name="Harvey TCR"/> [[Earth:Europe|Europe]] is rarely affected by tropical cyclones; however, the continent regularly encounters storms after they transitioned into extratropical cyclones. Only one tropical depression &ndash; Vince in 2005 &ndash; struck {{wipe|Spain}},<ref>{{cite report|first=James L.|last=Franklin|title=Tropical Cyclone Report: Hurricane Vince|publisher=National Hurricane Center|date=February 22, 2006|access-date=August 14, 2011|url=http://www.nhc.noaa.gov/data/tcr/AL242005_Vince.pdf|archive-date=October 2, 2015|archive-url=https://web.archive.org/web/20151002011818/http://www.nhc.noaa.gov/data/tcr/AL242005_Vince.pdf|url-status=live}}</ref> and only one subtropical cyclone &ndash; Subtropical Storm Alpha in 2020 &ndash; struck Portugal.<ref>{{cite report|title=Subtropical Storm Alpha Discussion Number 2|url=https://www.nhc.noaa.gov/archive/2020/al24/al242020.discus.002.shtml?|publisher=National Hurricane Center|access-date=September 18, 2020|date=September 18, 2020|first1=Eric|last1=Blake|archive-date=October 9, 2020|archive-url=https://web.archive.org/web/20201009024154/https://www.nhc.noaa.gov/archive/2020/al24/al242020.discus.002.shtml|url-status=live}}</ref> Occasionally, there are [[Earth:Mediterranean tropical-like cyclone|tropical-like cyclones]] in the [[Place:Mediterranean Sea|Mediterranean Sea]].<ref>{{cite journal|author=Emanuel, K.|url=https://www.researchgate.net/publication/26438265|title=Genesis and maintenance of 'Mediterranean hurricanes'|journal=Advances in Geosciences|date=June 2005|volume=2|pages=217–220|doi=10.5194/adgeo-2-217-2005|bibcode=2005AdG.....2..217E|doi-access=free|access-date=May 23, 2022|archive-date=May 23, 2022|archive-url=https://web.archive.org/web/20220523221113/https://www.researchgate.net/publication/26438265_Genesis_and_maintenance_of_Mediterranean_hurricanes|url-status=live}}</ref> The northern portion of [[Earth:South America|South America]] experiences occasional tropical cyclones, with 173&nbsp;fatalities from Tropical Storm Bret in August 1993.<ref>{{cite web|last1=Pielke|first1=R. A. Jr.|last2=Rubiera|first2=J|last3=Landsea|first3=C|last4=Fernández|first4=M. L.|last5=Klein|first5=R|year=2003|title=Hurricane Vulnerability in Latin America & The Caribbean|publisher=National Hazards Review|access-date=July 20, 2006|url=http://sciencepolicy.colorado.edu/admin/publication_files/resource-1769-2003.21.pdf|archive-date=2006-08-10|archive-url=https://web.archive.org/web/20060810043441/http://sciencepolicy.colorado.edu/admin/publication_files/resource-1769-2003.21.pdf|url-status=live}}</ref><ref>{{cite report|first1=Ed |last1=Rappaport|date=December 9, 1993|title=Tropical Storm Bret Preliminary Report|url=http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1993/bret/prenhc/prelim03.gif|access-date=August 11, 2015|publisher=National Hurricane Center|page=3|format=GIF|archive-date=March 3, 2016|archive-url=https://web.archive.org/web/20160303220621/http://www.nhc.noaa.gov/archive/storm_wallets/atlantic/atl1993/bret/prenhc/prelim03.gif|url-status=live}}</ref> The South Atlantic Ocean is generally inhospitable to the formation of a tropical storm.<ref>{{cite book|author=Landsea, Christopher W. |date=July 13, 2005 |title=Tropical Cyclone Frequently Asked Question |chapter=Subject: Tropical Cyclone Names: G6) Why doesn't the South Atlantic Ocean experience tropical cyclones? |publisher=United States National Oceanic and Atmospheric Administration's Hurricane Research Division |access-date=February 7, 2015 |chapter-url=http://www.aoml.noaa.gov/hrd/tcfaq/G6.html |archive-url=https://web.archive.org/web/20150327070050/http://www.aoml.noaa.gov/hrd/tcfaq/G6.html |archive-date=March 27, 2015 |url-status=live }}</ref> However, in March 2004, Hurricane Catarina struck southeastern {{wipe|Brazil}} as the first hurricane on record in the South Atlantic Ocean.<ref>{{cite journal |last1=McTaggart-Cowan |first1=Ron |last2=Bosart |first2=Lance F. |last3=Davis |first3=Christopher A. |last4=Atallah |first4=Eyad H. |last5=Gyakum |first5=John R. |last6=Emanuel |first6=Kerry A. |title=Analysis of Hurricane Catarina (2004) |journal=Monthly Weather Review |date=November 2006 |volume=134 |issue=11 |pages=3029–3053 |url=https://texmex.mit.edu/pub/emanuel/PAPERS/cowan_etal_2006.pdf |access-date=May 23, 2022 |publisher=American Meteorological Society |doi=10.1175/MWR3330.1 |bibcode=2006MWRv..134.3029M |archive-date=August 30, 2021 |archive-url=https://web.archive.org/web/20210830230858/http://texmex.mit.edu/pub/emanuel/PAPERS/cowan_etal_2006.pdf |url-status=live }}</ref>

===Environmental effects===
Although cyclones take an enormous toll in lives and personal property, they may be important factors in the precipitation regimes of places they affect, as they may bring much-needed precipitation to otherwise dry regions.<ref name="2005 EPac outlook">[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]. [http://www.cpc.ncep.noaa.gov/products/Epac_hurr/Epac_hurricane.html 2005 Tropical Eastern North Pacific Hurricane Outlook.] {{Webarchive|url=https://web.archive.org/web/20150612041026/http://www.cpc.ncep.noaa.gov/products/Epac_hurr/Epac_hurricane.html |date=June 12, 2015 }}. Retrieved May 2, 2006.</ref> Their precipitation may also alleviate drought conditions by restoring soil moisture, though one study focused on the Southeastern United States suggested tropical cyclones did not offer significant drought recovery.<ref name="DontFix">{{cite news |title=Summer tropical storms don't fix drought conditions |url=https://www.sciencedaily.com/releases/2015/05/150527150948.htm |newspaper=ScienceDaily |access-date=April 10, 2021 |date=May 27, 2015 |archive-date=October 9, 2021 |archive-url=https://web.archive.org/web/20211009103634/https://www.sciencedaily.com/releases/2015/05/150527150948.htm |url-status=live }}</ref><ref name="Yoo et al. (2015)">{{cite journal |last1=Yoo |first1=Jiyoung |last2=Kwon |first2=Hyun-Han |last3=So |first3=Byung-Jin |last4=Rajagopalan |first4=Balaji |last5=Kim |first5=Tae-Woong |title=Identifying the role of typhoons as drought busters in South Korea based on hidden Markov chain models: ROLE OF TYPHOONS AS DROUGHT BUSTERS |journal=Geophysical Research Letters |date=April 28, 2015 |volume=42 |issue=8 |pages=2797–2804 |doi=10.1002/2015GL063753|doi-access=free }}</ref><ref name="Kam et al. (2013)">{{cite journal |last1=Kam |first1=Jonghun |last2=Sheffield |first2=Justin |last3=Yuan |first3=Xing|author4-link=Eric Franklin Wood |last4=Wood |first4=Eric F. |title=The Influence of Atlantic Tropical Cyclones on Drought over the Eastern United States (1980–2007) |journal=Journal of Climate |date=May 15, 2013 |volume=26 |issue=10 |pages=3067–3086 |doi=10.1175/JCLI-D-12-00244.1 |publisher=American Meteorological Society|bibcode=2013JCli...26.3067K |doi-access=free }}</ref> Tropical cyclones also help maintain the global heat balance by moving warm, moist tropical air to the middle latitudes and [[Earth:Polar regions of Earth|polar regions]],<ref name="JetStream introduction">{{cite web|url=http://www.srh.noaa.gov/jetstream/tropics/tc.htm|author=National Weather Service|work=JetStream&nbsp;– An Online School for Weather|publisher=National Oceanic & Atmospheric Administration|title=Tropical Cyclone Introduction|access-date=September 7, 2010|date=October 19, 2005|archive-url=https://web.archive.org/web/20120614093509/http://www.srh.noaa.gov/jetstream/tropics/tc.htm|archive-date=June 14, 2012|url-status=live}}</ref> and by regulating the [[Earth:Thermohaline circulation|thermohaline circulation]] through [[Earth:Upwelling|upwelling]].<ref>{{cite journal|last=Emanuel|first=Kerry|title=Contribution of tropical cyclones to meridional heat transport by the oceans|journal=[[Earth:Journal of Geophysical Research|Journal of Geophysical Research]]|date=July 2001|volume=106|issue=D14|pages=14771–14781|doi=10.1029/2000JD900641|bibcode = 2001JGR...10614771E |doi-access=free}}</ref> Research on Pacific cyclones has demonstrated that deeper layers of the ocean receive a [[Physics:Heat transfer physics|heat transfer]] from these powerful storms.<ref>Alex Fox. (20 June 2023). "New Measurements Suggest Tropical Cyclones May Influence Global Climate". [https://scripps.ucsd.edu/news/new-measurements-suggest-tropical-cyclones-may-influence-global-climate UC San Diego. Scripps Institution of Oceanography website] Retrieved 30 June 2023.</ref><ref>{{Cite journal |last1=Gutiérrez Brizuela |first1=Noel |last2=Alford |first2=Matthew H. |last3=Xie |first3=Shang-Ping |author-link3=Shang-Ping Xie |last4=Sprintall |first4=Janet |last5=Voet |first5=Gunnar |last6=Warner |first6=Sally J. |last7=Hughes |first7=Kenneth |last8=Moum |first8=James N. |title=Prolonged thermocline warming by near-inertial internal waves in the wakes of tropical cyclones |journal=Proceedings of the National Academy of Sciences of the United States of America |date=2023 |volume=120 |issue=26 |pages=e2301664120 |doi=10.1073/pnas.2301664120 |issn=0027-8424 |pmid=37339203|doi-access=free |pmc=10293854 |bibcode=2023PNAS..12001664G }}</ref> The storm surge and winds of hurricanes may be destructive to human-made structures, but they also stir up the waters of coastal [[Earth:Estuary|estuaries]], which are typically important [[Biology:Fish reproduction|fish breeding]] locales.<ref name="Christopherson">{{cite book|author=Christopherson, Robert W.|year=1992|title=Geosystems: An Introduction to Physical Geography|pages=222–224|publisher=Macmillan Publishing Company|location=New York|isbn=978-0-02-322443-0}}</ref> Ecosystems, such as saltmarshes and [[Biology:Mangrove forest|Mangrove forest]]s, can be severely damaged or destroyed by tropical cyclones, which erode land and destroy vegetation.<ref>{{cite journal |last1=Khanna |first1=Shruti |last2=Santos |first2=Maria J. |last3=Koltunov |first3=Alexander |last4=Shapiro |first4=Kristen D. |last5=Lay |first5=Mui |last6=Ustin |first6=Susan L. |title=Marsh Loss Due to Cumulative Impacts of Hurricane Isaac and the Deepwater Horizon Oil Spill in Louisiana |journal=Remote Sensing |date=February 17, 2017 |volume=9 |issue=2 |page=169 |doi=10.3390/rs9020169 |publisher=MDPI|bibcode=2017RemS....9..169K |doi-access=free }}</ref><ref>{{cite journal |last1=Osland |first1=Michael J. |last2=Feher |first2=Laura C. |last3=Anderson |first3=Gordon H. |last4=Varvaeke |first4=William C. |last5=Krauss |first5=Ken W. |last6=Whelan |first6=Kevin R.T. |last7=Balentine |first7=Karen M. |last8=Tiling-Range |first8=Ginger |last9=Smith III |first9=Thomas J. |last10=Cahoon |first10=Donald R. |title=A Tropical Cyclone-Induced Ecological Regime Shift: Mangrove Forest Conversion to Mudflat in Everglades National Park (Florida, USA) |journal=Wetlands and Climate Change |date=May 26, 2020 |volume=40 |issue=5 |pages=1445–1458 |doi=10.1007/s13157-020-01291-8 |url=https://link.springer.com/article/10.1007/s13157-020-01291-8 |access-date=May 27, 2022 |publisher=Springer |bibcode=2020Wetl...40.1445O |s2cid=218897776 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517122435/https://link.springer.com/article/10.1007/s13157-020-01291-8 |url-status=live }}</ref> Tropical cyclones can cause harmful [[Biology:Algal bloom|algae blooms]] to form in bodies of water by increasing the amount of nutrients available.<ref name="Oil+Algae"/><ref>{{cite journal |last1=Zang |first1=Zhengchen |last2=Xue |first2=Z. George |last3=Xu |first3=Kehui |last4=Bentley |first4=Samuel J. |last5=Chen |first5=Qin |last6=D'Sa |first6=Eurico J. |last7=Zhang |first7=Le |last8=Ou |first8=Yanda |title=The role of sediment-induced light attenuation on primary production during Hurricane Gustav (2008) |journal=Biogeosciences |date=October 20, 2020 |volume=17 |issue=20 |pages=5043–5055 |doi=10.5194/bg-17-5043-2020 |url=https://bg.copernicus.org/articles/17/5043/2020/ |access-date=May 19, 2022 |publisher=Copernicus Publications |bibcode=2020BGeo...17.5043Z |s2cid=238986315 |archive-date=January 19, 2022 |archive-url=https://web.archive.org/web/20220119222647/https://bg.copernicus.org/articles/17/5043/2020/ |url-status=live |doi-access=free |hdl=1912/26507 |hdl-access=free }}</ref><ref>{{cite journal |last1=Huang |first1=Wenrui |last2=Mukherjee |first2=Debraj |last3=Chen |first3=Shuisen |title=Assessment of Hurricane Ivan impact on chlorophyll-a in Pensacola Bay by MODIS 250 m remote sensing |journal=Marine Pollution Bulletin |date=March 2011 |volume=62 |issue=3 |pages=490–498 |doi=10.1016/j.marpolbul.2010.12.010 |url=https://www.sciencedirect.com/science/article/abs/pii/S0025326X10005333 |access-date=May 19, 2022 |pmid=21272900 |bibcode=2011MarPB..62..490H }}</ref> Insect populations can decrease in both quantity and diversity after the passage of storms.<ref>{{cite journal |last1=Chen |first1=Xuan |last2=Adams |first2=Benjamin J. |last3=Platt |first3=William J. |last4=Hooper-Bùi |first4=Linda M. |title=Effects of a tropical cyclone on salt marsh insect communities and post-cyclone reassembly processes |journal=Ecography |date=February 28, 2020 |volume=43 |issue=6 |pages=834–847 |doi=10.1111/ecog.04932 |publisher=Wiley Online Library |s2cid=212990211 |doi-access=free |bibcode=2020Ecogr..43..834C }}</ref> Strong winds associated with tropical cyclones and their remnants are capable of felling thousands of trees, causing damage to forests.<ref>{{cite news |title=Tempestade Leslie provoca grande destruição nas Matas Nacionais |trans-title=Storm Leslie wreaks havoc in the National Forests |url=https://www.noticiasdecoimbra.pt/tempestade-leslie-provoca-grande-destruicao-nas-matas-nacionais/ |access-date=May 27, 2022 |work=Notícias de Coimbra |date=October 17, 2018 |language=pt |archive-date=January 28, 2019 |archive-url=https://web.archive.org/web/20190128031143/https://www.noticiasdecoimbra.pt/tempestade-leslie-provoca-grande-destruicao-nas-matas-nacionais/ |url-status=live }}</ref>

When hurricanes surge upon shore from the ocean, salt is introduced to many freshwater areas and raises the [[Earth:Salinity|salinity]] levels too high for some habitats to withstand. Some are able to cope with the salt and recycle it back into the ocean, but others can not release the extra surface water quickly enough or do not have a large enough freshwater source to replace it. Because of this, some species of plants and vegetation die due to the excess salt.<ref>{{cite web|last=Doyle|first=Thomas|title=Wind damage and Salinity Effects of Hurricanes Katrina and Rita on Coastal Baldcypress Forests of Louisiana|url=http://pubs.usgs.gov/circ/1306/pdf/c1306_ch6_f.pdf|access-date=February 13, 2014|year=2005|archive-url=https://web.archive.org/web/20160304040402/http://pubs.usgs.gov/circ/1306/pdf/c1306_ch6_f.pdf|archive-date=March 4, 2016|url-status=live}}</ref> In addition, hurricanes can carry toxins and acids onshore when they make landfall. The floodwater can pick up the toxins from different spills and contaminate the land that it passes over. These toxins are harmful to the people and animals in the area, as well as the environment around them.<ref>{{cite web|last=Cappielo|first=Dina|title=Spills from hurricanes stain coast With gallery|url=http://www.chron.com/news/hurricanes/article/Spills-from-hurricanes-stain-coast-With-gallery-1915858.php|work=Houston Chronicle|access-date=February 12, 2014|year=2005|archive-url=https://web.archive.org/web/20140425055112/http://www.chron.com/news/hurricanes/article/Spills-from-hurricanes-stain-coast-With-gallery-1915858.php|archive-date=April 25, 2014|url-status=live}}</ref> Tropical cyclones can cause [[Earth:Oil spill|oil spills]] by damaging or destroying pipelines and storage facilities.<ref>{{cite journal |last1=Pine |first1=John C. |title=Hurricane Katrina and Oil Spills: Impact on Coastal and Ocean Environments |journal=Oceanography |year=2006 |volume=19 |issue=2 |pages=37–39 |url=https://tos.org/oceanography/assets/docs/19-2_pine.pdf |access-date=May 19, 2022 |publisher=The Oceanography Society |doi=10.5670/oceanog.2006.61 |archive-date=January 20, 2022 |archive-url=https://web.archive.org/web/20220120022223/https://tos.org/oceanography/assets/docs/19-2_pine.pdf |url-status=live }}</ref><ref name="Oil+Algae">{{cite journal |last1=You |first1=Zai-Jin |title=Tropical Cyclone-Induced Hazards Caused by Storm Surges and Large Waves on the Coast of China |journal=Geosciences |date=March 18, 2019 |volume=9 |issue=3 |page=131 |doi=10.3390/geosciences9030131 |bibcode=2019Geosc...9..131Y |issn=2076-3263|doi-access=free }}</ref><ref name="Oil + Chemicals">{{cite journal |last1=Santella |first1=Nicholas |last2=Steinberg |first2=Laura J. |last3=Sengul |first3=Hatice |title=Petroleum and Hazardous Material Releases from Industrial Facilities Associated with Hurricane Katrina |journal=Risk Analysis |date=April 12, 2010 |volume=30 |issue=4 |pages=635–649 |doi=10.1111/j.1539-6924.2010.01390.x |pmid=20345576 |bibcode=2010RiskA..30..635S |s2cid=24147578 |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1539-6924.2010.01390.x |access-date=May 21, 2022 }}</ref> Similarly, chemical spills have been reported when chemical and processing facilities were damaged.<ref name="Oil + Chemicals"/><ref>{{cite journal |last1=Qin |first1=Rongshui |last2=Khakzad |first2=Nima |last3=Zhu |first3=Jiping |title=An overview of the impact of Hurricane Harvey on chemical and process facilities in Texas |journal=International Journal of Disaster Risk Reduction |date=May 2020 |volume=45 |page=101453 |doi=10.1016/j.ijdrr.2019.101453 |url=https://www.sciencedirect.com/science/article/abs/pii/S2212420919313949 |access-date=May 19, 2022 |bibcode=2020IJDRR..4501453Q |s2cid=214418578 }}</ref><ref>{{cite journal |last1=Misuri |first1=Alessio |last2=Moreno |first2=Valeria Casson |last3=Quddus |first3=Noor |last4=Cozzani |first4=Valerio |title=Lessons learnt from the impact of hurricane Harvey on the chemical and process industry |journal=Reliability Engineering & System Safety |date=October 2019 |volume=190 |page=106521 |doi=10.1016/j.ress.2019.106521 |url=https://www.sciencedirect.com/science/article/abs/pii/S0951832019303990 |access-date=May 19, 2022 |s2cid=191214528 }}</ref> Waterways have become contaminated with toxic levels of metals such as [[Chemistry:Nickel|nickel]], [[Chemistry:Chromium|chromium]], and [[Chemistry:Mercury (element)|mercury]] during tropical cyclones.<ref>{{cite news |last1=Cañedo |first1=Sibely |title=Tras el Huracán Willa, suben niveles de metales en río Baluarte |trans-title=After Hurricane Willa, metal levels rise in the Baluarte River|url=https://www.noroeste.com.mx/publicaciones/view/huracan-willa-azoto-en-el-sur-y-niveles-de-cromo-niquel-y-mercurio-subieron-en-rio-baluarte-1159453 |access-date=May 19, 2022 |publisher=Noreste |date=March 29, 2019 |archive-url=https://web.archive.org/web/20200930145023/https://www.noroeste.com.mx/publicaciones/view/huracan-willa-azoto-en-el-sur-y-niveles-de-cromo-niquel-y-mercurio-subieron-en-rio-baluarte-1159453 |archive-date=September 30, 2020 |language=es}}</ref><ref name="Erosion + Mercury">{{cite journal |last1=Dellapenna |first1=Timothy M. |last2=Hoelscher |first2=Christena |last3=Hill |first3=Lisa |last4=Al Mukaimi |first4=Mohammad E. |last5=Knap |first5=Anthony |title=How tropical cyclone flooding caused erosion and dispersal of mercury-contaminated sediment in an urban estuary: The impact of Hurricane Harvey on Buffalo Bayou and the San Jacinto Estuary, Galveston Bay, USA |journal=Science of the Total Environment |date=December 15, 2020 |volume=748 |page=141226 |doi=10.1016/j.scitotenv.2020.141226 |pmid=32818899 |pmc=7606715 |bibcode=2020ScTEn.748n1226D }}</ref>

Tropical cyclones can have an extensive effect on geography, such as creating or destroying land.<ref name="Land created"/><ref name="Land Destroyed"/> Cyclone Bebe increased the size of Tuvalu island, Funafuti Atoll, by nearly 20%.<ref name="Land created">{{cite journal |last1=Volto |first1=Natacha |last2=Duvat |first2=Virginie K.E. |title=Applying Directional Filters to Satellite Imagery for the Assessment of Tropical Cyclone Impacts on Atoll Islands |journal=Coastal Research |date=July 9, 2020 |volume=36 |issue=4 |pages=732–740 |doi=10.2112/JCOASTRES-D-19-00153.1 |url=https://meridian.allenpress.com/jcr/article-abstract/36/4/732/440511/Applying-Directional-Filters-to-Satellite-Imagery |access-date=May 21, 2022 |publisher=Meridian Allen Press |s2cid=220323810 |archive-date=January 25, 2021 |archive-url=https://web.archive.org/web/20210125103957/https://meridian.allenpress.com/jcr/article-abstract/36/4/732/440511/Applying-Directional-Filters-to-Satellite-Imagery |url-status=live }}</ref><ref>{{cite journal |last1=Onaka |first1=Susumu |last2=Ichikawa |first2=Shingo |last3=Izumi |first3=Masatoshi |last4=Uda |first4=Takaaki |last5=Hirano |first5=Junichi |last6=Sawada |first6=Hideki |title=Effectiveness of Gravel Beach Nourishment on Pacific Island |journal=Asian and Pacific Coasts |year=2017 |pages=651–662 |doi=10.1142/9789813233812_0059 |url=https://www.worldscientific.com/doi/abs/10.1142/9789813233812_0059 |access-date=May 21, 2022 |publisher=World Scientific |isbn=978-981-323-380-5 |archive-date=May 16, 2022 |archive-url=https://web.archive.org/web/20220516233836/https://www.worldscientific.com/doi/abs/10.1142/9789813233812_0059 |url-status=live }}</ref><ref>{{cite journal |last1=Kench |first1=P.S. |last2=McLean |first2=R.F. |last3=Owen |first3=S.D. |last4=Tuck |first4=M. |last5=Ford |first5=M.R. |title=Storm-deposited coral blocks: A mechanism of island genesis, Tutaga island, Funafuti atoll, Tuvalu |journal=Geology |date=October 1, 2018 |volume=46 |issue=10 |pages=915–918 |doi=10.1130/G45045.1 |url=https://pubs.geoscienceworld.org/gsa/geology/article-abstract/46/10/915/548204/Storm-deposited-coral-blocks-A-mechanism-of-island |access-date=May 21, 2022 |publisher=Geo Science World |bibcode=2018Geo....46..915K |s2cid=135443385 }}</ref> Hurricane Walaka destroyed the small East Island in 2018,<ref name="Land Destroyed">{{cite book |last1=Bush |first1=Martin J. |title=Climate Change and Renewable Energy |date=October 9, 2019 |publisher=Springer |isbn=978-3-030-15423-3 |pages=421–475 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-030-15424-0_9 |access-date=May 21, 2022 |chapter=How to End the Climate Crisis |doi=10.1007/978-3-030-15424-0_9 |s2cid=211444296 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517014331/https://link.springer.com/chapter/10.1007/978-3-030-15424-0_9 |url-status=live }}</ref><ref>{{cite journal |last1=Baker |first1=Jason D. |last2=Harting |first2=Albert L. |last3=Johanos |first3=Thea C. |last4=London |first4=Joshua M. |last5=Barbieri |first5=Michelle M. |last6=Littnan |first6=Charles L. |title=Terrestrial Habitat Loss and the Long-term Viability of the French Frigate Shoals Hawaiian Monk Seal Subpopulation |journal=NOAA Technical Memorandum NMFS-PIFSC |date=August 2020 |doi=10.25923/76vx-ve75 |url=https://repository.library.noaa.gov/view/noaa/26090 |access-date=May 20, 2022 |publisher=NOAA Fisheries |archive-date=May 12, 2022 |archive-url=https://web.archive.org/web/20220512003115/https://repository.library.noaa.gov/view/noaa/26090 |url-status=live }}</ref> which destroyed the habitat for the endangered [[Biology:Hawaiian monk seal|Hawaiian monk seal]], as well as, threatened [[Biology:Sea turtle|sea turtle]]s and seabirds.<ref>{{cite book |last1=Tokar |first1=Brian |last2=Gilbertson |first2=Tamra |title=Climate Justice and Community Renewal: Resistance and Grassroots Solutions |date=March 31, 2020 |page=70 |publisher=Routledge |isbn=9781000049213 |url=https://books.google.com/books?id=ORHaDwAAQBAJ&q=hurricane+walaka+east+island+monk+seal |access-date=May 27, 2022 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517122435/https://books.google.com/books?id=ORHaDwAAQBAJ&dq=hurricane+walaka+east+island+monk+seal&lr=&source=gbs_navlinks_s |url-status=live }}</ref> [[Earth:Landslide|Landslide]]s frequently occur during tropical cyclones and can vastly alter landscapes; some storms are capable of causing hundreds to tens of thousands of landslides.<ref>{{cite journal |last1=Samodra |first1=Guruh |last2=Ngadisih |first2=Ngadisih |last3=Malawani |first3=Mukhamad Ngainul |last4=Mardiatno |first4=Djati |last5=Cahyadi |first5=Ahmad |last6=Nugroho |first6=Ferman Setia |title=Frequency–magnitude of landslides affected by the 27–29 November 2017 Tropical Cyclone Cempaka in Pacitan, East Java |journal=Journal of Mountain Science |date=April 11, 2020 |volume=17 |issue=4 |pages=773–786 |url=https://link.springer.com/article/10.1007/s11629-019-5734-y |access-date=May 21, 2022 |publisher=Springer |doi=10.1007/s11629-019-5734-y |bibcode=2020JMouS..17..773S |s2cid=215725140 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517014552/https://link.springer.com/article/10.1007/s11629-019-5734-y |url-status=live }}</ref><ref>{{cite journal |last1=Zinke |first1=Laura |title=Hurricanes and landslides |journal=Geomorphology |date=April 28, 2021 |volume=2 |issue=5 |page=304 |doi=10.1038/s43017-021-00171-x |url=https://www.nature.com/articles/s43017-021-00171-x |access-date=May 21, 2022 |publisher=Nature Reviews Earth & Environment |bibcode=2021NRvEE...2..304Z |s2cid=233435990 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517015939/https://www.nature.com/articles/s43017-021-00171-x |url-status=live }}</ref><ref>{{cite journal |last1=Tien |first1=Pham Van |last2=Luong |first2=Le Hong |last3=Duc |first3=Do Minh |last4=Trinh |first4=Phan Trong |last5=Quynh |first5=Dinh Thi |last6=Lan |first6=Nguyen Chau |last7=Thuy |first7=Dang Thi |last8=Phi |first8=Nguyen Quoc |last9=Cuong |first9=Tran Quoc |last10=Dang |first10=Khang |last11=Loi |first11=Doan Huy |title=Rainfall-induced catastrophic landslide in Quang Tri Province: the deadliest single landslide event in Vietnam in 2020 |journal=Landslides |date=April 9, 2021 |volume=18 |issue=6 |pages=2323–2327 |doi=10.1007/s10346-021-01664-y |url=https://link.springer.com/article/10.1007/s10346-021-01664-y |access-date=May 21, 2022 |publisher=Springer |bibcode=2021Lands..18.2323V |s2cid=233187785 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517014536/https://link.springer.com/article/10.1007/s10346-021-01664-y |url-status=live }}</ref><ref>{{cite journal |last1=Santos |first1=Gemma Dela Cruz |title=2020 tropical cyclones in the Philippines: A review |journal=Tropical Cyclone Research and Review |date=September 20, 2021 |volume=10 |issue=3 |pages=191–199 |doi=10.1016/j.tcrr.2021.09.003 |bibcode=2021TCRR...10..191S |s2cid=239244161 |doi-access=free }}</ref> Storms can erode coastlines over an extensive area and transport the sediment to other locations.<ref name="Erosion + Mercury"/><ref>{{cite journal |last1=Mishra |first1=Manoranjan |last2=Kar |first2=Dipika |last3=Debnath |first3=Manasi |last4=Sahu |first4=Netrananda |last5=Goswami |first5=Shreerup |title=Rapid eco-physical impact assessment of tropical cyclones using geospatial technology: a case from severe cyclonic storms Amphan |journal=Natural Hazards |date=August 30, 2021 |volume=110 |issue=3 |pages=2381–2395 |doi=10.1007/s11069-021-05008-w |url=https://link.springer.com/article/10.1007/s11069-021-05008-w |access-date=May 21, 2022 |publisher=Springer |s2cid=237358608 |archive-date=May 17, 2022 |archive-url=https://web.archive.org/web/20220517010258/https://link.springer.com/article/10.1007/s11069-021-05008-w |url-status=live }}</ref><ref>{{cite journal |last1=Tamura |first1=Toru |last2=Nicholas |first2=William A. |last3=Oliver |first3=Thomas S. N. |last4=Brooke |first4=Brendan P. |title=Coarse-sand beach ridges at Cowley Beach, north-eastern Australia: Their formative processes and potential as records of tropical cyclone history |journal=Sedimentology |date=July 14, 2017 |volume=65 |issue=3 |pages=721–744 |doi=10.1111/sed.12402 |publisher=Wiley Library |s2cid=53403886 |doi-access=free }}</ref>

== Climatology ==
Tropical cyclones have occurred around the world for millennia. Reanalyses and research are being undertaken to extend the historical record, through the usage of [[Earth:Proxy (climate)|proxy data]] such as overwash deposits, [[Earth:Beach ridge|beach ridges]] and historical documents such as diaries.<ref name="6000 WA">{{cite journal |author=Nott, Jonathan |date=March 1, 2011 |title=A 6000 year tropical cyclone record from Western Australia |url=https://www.sciencedirect.com/science/article/abs/pii/S0277379110004324 |url-status=live |journal=Quaternary Science Reviews |volume=30 |issue=5 |pages=713–722 |bibcode=2011QSRv...30..713N |doi=10.1016/j.quascirev.2010.12.004 |issn=0277-3791 |archive-url=https://web.archive.org/web/20201221144531/https://www.sciencedirect.com/science/article/abs/pii/S0277379110004324 |archive-date=December 21, 2020 |access-date=March 13, 2021}}</ref> Major tropical cyclones leave traces in [[Earth:Overwash|overwash records]] and shell layers in some coastal areas, which have been used to gain insight into hurricane activity over the past thousands of years.<ref name=":8">{{Citation|last1=Muller|first1=Joanne|title=Recent Advances in the Emerging Field of Paleotempestology|year=2017|work=Hurricanes and Climate Change: Volume 3|pages=1–33|editor-last=Collins|editor-first=Jennifer M.|place=Cham|publisher=Springer International Publishing|language=en|doi=10.1007/978-3-319-47594-3_1|isbn=978-3-319-47594-3|access-date=|last2=Collins|first2=Jennifer M.|last3=Gibson|first3=Samantha|last4=Paxton|first4=Leilani|s2cid=133456333 |editor2-last=Walsh|editor2-first=Kevin}}</ref> Sediment records in Western Australia suggest an intense tropical cyclone in the [[History:4th millennium BC|4th millennium BC]].<ref name="6000 WA"/> Proxy records based on [[Earth:Paleotempestology|paleotempestological]] research have revealed that major hurricane activity along the Gulf of Mexico coast varies on timescales of centuries to millennia.<ref name="Liu1999">{{cite conference|first=Kam-biu|last=Liu|title=Millennial-scale variability in catastrophic hurricane landfalls along the Gulf of Mexico coast|conference=23rd Conference on Hurricanes and Tropical Meteorology|publisher=American Meteorological Society|year=1999|location=Dallas, TX|pages=374–377}}</ref><ref name="LiuFearn2000">{{cite journal |last=Liu |first=Kam-biu|author2=Fearn, Miriam L.|year=2000|title=Reconstruction of Prehistoric Landfall Frequencies of Catastrophic Hurricanes in Northwestern Florida from Lake Sediment Records|journal=Quaternary Research|volume=54|issue=2|pages=238–245|doi=10.1006/qres.2000.2166|bibcode = 2000QuRes..54..238L |s2cid=140723229}}</ref> In the year 957, a powerful typhoon struck southern China, killing around 10,000&nbsp;people due to flooding.<ref>{{cite web|title=Reconstruction of an 8,000-year record of typhoons in the Pearl River estuary, China|author=G. Huang|author2=W.W. S. Yim|date=January 2001|website=University of Hong Kong|url=https://hub.hku.hk/bitstream/10722/188774/2/Content.pdf?accept=1|access-date=April 2, 2021|archive-date=July 20, 2021|archive-url=https://web.archive.org/web/20210720175126/https://hub.hku.hk/bitstream/10722/188774/2/Content.pdf?accept=1|url-status=live}}</ref> The Spanish colonization of Mexico described "tempestades" in 1730,<ref name="calif">{{cite book|author=Arnold Court|publisher=California State University|location=Northridge, California|year=1980|title=Tropical Cyclone Effects on California|series=NOAA technical memorandum NWS WR; 159|pages=2, 4, 6, 8, 34|access-date=2012-02-02|url=http://babel.hathitrust.org/cgi/pt?id=uc1.31822009671892;seq=10;size=125;view=image|archive-date=October 1, 2018|archive-url=https://web.archive.org/web/20181001115852/https://babel.hathitrust.org/cgi/pt?id=uc1.31822009671892;seq=10;size=125;view=image|url-status=live}}</ref> although the official record for Pacific hurricanes only dates to 1949.{{hurdat}} In the south-west Indian Ocean, the tropical cyclone record goes back to 1848.<ref>{{cite report|author=Philippe Caroff|date=June 2011|title=Operational procedures of TC satellite analysis at RSMC La Reunion|publisher=World Meteorological Organization|access-date=2013-04-22|url=https://library.wmo.int/doc_num.php?explnum_id=6291|format=PDF|display-authors=0|archive-date=April 27, 2021|archive-url=https://web.archive.org/web/20210427174202/https://library.wmo.int/doc_num.php?explnum_id=6291|url-status=live}}</ref> In 2003, the Atlantic hurricane reanalysis project examined and analyzed the historical record of tropical cyclones in the Atlantic back to 1851, extending the existing database from 1886.<ref>{{cite web|title=Documentation for 1851–1910 Alterations and Additions to the HURDAT Database|author=Christopher W. Landsea|display-authors=0|series=The Atlantic Hurricane Database Re-analysis Project|publisher=Hurricane Research Division|url=https://www.aoml.noaa.gov/hrd/hurdat/august01/rpibook-jan03.htm|access-date=April 27, 2021|archive-date=June 15, 2021|archive-url=https://web.archive.org/web/20210615030803/https://www.aoml.noaa.gov/hrd/hurdat/august01/rpibook-jan03.htm|url-status=live}}</ref>

Before satellite imagery became available during the 20th century, many of these systems went undetected unless it impacted land or a ship encountered it by chance.<ref name="Global Guide 2017"/> Often in part because of the threat of hurricanes, many coastal regions had sparse population between major ports until the advent of automobile tourism; therefore, the most severe portions of hurricanes striking the coast may have gone unmeasured in some instances. The combined effects of ship destruction and remote landfall severely limit the number of intense hurricanes in the official record before the era of hurricane reconnaissance aircraft and satellite meteorology. Although the record shows a distinct increase in the number and strength of intense hurricanes, therefore, experts regard the early data as suspect.<ref name="BOM TC Guide 1.3">{{cite web|work=Global Guide to Tropical Cyclone Forecasting |publisher=Bureau of Meteorology |url=http://www.cawcr.gov.au/publications/BMRC_archive/tcguide/ch1/ch1_3.htm |title=1.3: A Global Climatology |author=Neumann, Charles J |access-date=November 30, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20110601213525/http://www.cawcr.gov.au/publications/BMRC_archive/tcguide/ch1/ch1_3.htm |archive-date=June 1, 2011}}</ref> The ability of climatologists to make a long-term analysis of tropical cyclones is limited by the amount of reliable historical data.<ref>{{cite journal |last1=Knutson |first1=Thomas |last2=Camargo |first2=Suzana |last3=Chan |first3=Johnny |last4=Emanuel |first4=Kerry |last5=Ho |first5=Chang-Hoi |last6=Kossin |first6=James |last7=Mohapatra |first7=Mrutyunjay |last8=Satoh |first8=Masaki |last9=Sugi |first9=Masato |last10=Walsh |first10=Kevin |last11=Wu |first11=Liguang |title=TROPICAL CYCLONES AND CLIMATE CHANGE ASSESSMENT Part I: Detection and Attribution |journal=American Meteorological Society |date=October 1, 2019 |volume=100 |issue=10 |page=1988 |doi=10.1175/BAMS-D-18-0189.1 |bibcode=2019BAMS..100.1987K |hdl=1721.1/125577 |s2cid=191139413 |url=https://journals.ametsoc.org/view/journals/bams/100/10/bams-d-18-0189.1.xml?tab_body=pdf |access-date=April 17, 2021 |hdl-access=free |archive-date=August 13, 2021 |archive-url=https://web.archive.org/web/20210813210000/https://journals.ametsoc.org/view/journals/bams/100/10/bams-d-18-0189.1.xml?tab_body=pdf |url-status=live }}</ref> During the 1940s, routine aircraft reconnaissance started in both the Atlantic and Western Pacific basin during the mid-1940s, which provided ground truth data, however, early flights were only made once or twice a day.<ref name="Global Guide 2017"/> Polar-orbiting weather satellites were first launched by the United States [[Organization:National Aeronautics and Space Administration|National Aeronautics and Space Administration]] in 1960 but were not declared operational until 1965.<ref name="Global Guide 2017"/> However, it took several years for some of the warning centres to take advantage of this new viewing platform and develop the expertise to associate satellite signatures with storm position and intensity.<ref name="Global Guide 2017"/>

Each year on average, around 80 to 90 named tropical cyclones form around the world, of which over half develop hurricane-force winds of {{convert|65|kn|km/h mph|abbr=on|round=5}} or more.<ref name="Global Guide 2017"/> Worldwide, tropical cyclone activity peaks in late summer, when the difference between temperatures aloft and [[Physics:Sea surface temperature|sea surface temperature]]s is the greatest. However, each particular basin has its own seasonal patterns. On a worldwide scale, May is the least active month, while September is the most active month. November is the only month in which all the [[Earth:Tropical cyclone basins|tropical cyclone basins]] are in season.<ref name="AOML FAQ G1">{{cite web|author=[[Organization:Atlantic Oceanographic and Meteorological Laboratory|Atlantic Oceanographic and Meteorological Laboratory]], Hurricane Research Division |title=Frequently Asked Questions: When is hurricane season? |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] |access-date=July 25, 2006 |url=http://www.aoml.noaa.gov/hrd/tcfaq/G1.html |url-status=dead |archive-url=https://web.archive.org/web/20090506152735/http://www.aoml.noaa.gov/hrd/tcfaq/G1.html |archive-date=May 6, 2009}}</ref> In the Northern [[Earth:Atlantic Ocean|Atlantic Ocean]], a distinct cyclone season occurs from June 1 to November 30, sharply peaking from late August through September.<ref name="AOML FAQ G1"/> The statistical peak of the Atlantic hurricane season is September 10. The Northeast Pacific Ocean has a broader period of activity, but in a similar time frame to the Atlantic.<ref name="NHC Atl climatology">{{cite web|author=McAdie, Colin|publisher=National Hurricane Center|title=Tropical Cyclone Climatology|url=http://www.nhc.noaa.gov/climo/|date=May 10, 2007|access-date=June 9, 2007|archive-url=https://web.archive.org/web/20150321161433/http://www.nhc.noaa.gov/climo/|archive-date=March 21, 2015|url-status=live}}</ref> The Northwest Pacific sees tropical cyclones year-round, with a minimum in February and March and a peak in early September.<ref name="AOML FAQ G1"/> In the North Indian basin, storms are most common from April to December, with peaks in May and November.<ref name="AOML FAQ G1"/> In the Southern Hemisphere, the tropical cyclone year begins on July 1 and runs all year-round encompassing the tropical cyclone seasons, which run from November 1 until the end of April, with peaks in mid-February to early March.<ref name="AOML FAQ G1"/><ref name="SPAC TCOP" />

Of various [[Earth:Climate variability and change|modes of variability]] in the climate system, [[Earth:El Niño–Southern Oscillation|El Niño–Southern Oscillation]] has the largest effect on tropical cyclone activity.<ref name=":3">{{Cite web|website=Oxford Research Encyclopedia of Natural Hazard Science|publisher=Oxford University Press|last=Ramsay|first=Hamish|year=2017|title=The Global Climatology of Tropical Cyclones|url=https://oxfordre.com/view/10.1093/acrefore/9780199389407.001.0001/acrefore-9780199389407-e-79|access-date=|language=en|doi=10.1093/acrefore/9780199389407.013.79|isbn=9780199389407|archive-date=August 15, 2021|archive-url=https://web.archive.org/web/20210815230620/https://oxfordre.com/view/10.1093/acrefore/9780199389407.001.0001/acrefore-9780199389407-e-79|url-status=live}}</ref> Most tropical cyclones form on the side of the subtropical ridge closer to the equator, then move poleward past the ridge axis before recurving into the main belt of the [[Earth:Westerlies|Westerlies]].<ref>{{cite web|author=Joint Typhoon Warning Center|year=2006|title=3.3 JTWC Forecasting Philosophies|url=http://www.nrlmry.navy.mil/forecaster_handbooks/Philippines2/Forecasters%20Handbook%20for%20the%20Philippine%20Islands%20and%20Surrounding%20Waters%20Typhoon%20Forecasting.3.pdf|url-status=live|archive-url=https://web.archive.org/web/20071129132730/http://www.nrlmry.navy.mil/forecaster_handbooks/Philippines2/Forecasters%20Handbook%20for%20the%20Philippine%20Islands%20and%20Surrounding%20Waters%20Typhoon%20Forecasting.3.pdf|archive-date=November 29, 2007|access-date=February 11, 2007|publisher=United States Navy}}</ref> When the [[Earth:Subtropical ridge|subtropical ridge]] position shifts due to El Niño, so will the preferred tropical cyclone tracks. Areas west of Japan and [[Place:Korea|Korea]] tend to experience much fewer September–November tropical cyclone impacts during [[Earth:El Niño|El Niño]] and neutral years.<ref name="China">{{Cite journal|last1=Wu|first1=M.C.|last2=Chang|first2=W.L.|last3=Leung|first3=W.M.|year=2004|title=Impacts of El Niño–Southern Oscillation Events on Tropical Cyclone Landfalling Activity in the Western North Pacific|journal=Journal of Climate|volume=17|issue=6|pages=1419–1428|bibcode=2004JCli...17.1419W|citeseerx=10.1.1.461.2391|doi=10.1175/1520-0442(2004)017<1419:IOENOE>2.0.CO;2}}</ref> During [[Earth:La Niña|La Niña]] years, the formation of tropical cyclones, along with the subtropical ridge position, shifts westward across the western Pacific Ocean, which increases the landfall threat to China and much greater intensity in the {{wipe|Philippines}}.<ref name="China" /> The Atlantic Ocean experiences depressed activity due to increased vertical [[Physics:Wind shear|wind shear]] across the region during El Niño years.<ref>{{Cite journal|last=Klotzbach|first=Philip J.|year=2011|title=El Niño–Southern Oscillation's Impact on Atlantic Basin Hurricanes and U.S. Landfalls|journal=Journal of Climate|language=en|volume=24|issue=4|pages=1252–1263|bibcode=2011JCli...24.1252K|doi=10.1175/2010JCLI3799.1|issn=0894-8755|doi-access=free}}</ref> Tropical cyclones are further influenced by the Atlantic Meridional Mode, the [[Earth:Quasi-biennial oscillation|Quasi-biennial oscillation]] and the [[Earth:Madden–Julian oscillation|Madden–Julian oscillation]].<ref name=":3" /><ref>{{Citation|last1=Camargo|first1=Suzana J.|title=The Influence of Natural Climate Variability on Tropical Cyclones, and Seasonal Forecasts of Tropical Cyclone Activity|year=2010|url=https://www.worldscientific.com/doi/abs/10.1142/9789814293488_0011|work=Global Perspectives on Tropical Cyclones|volume=4|pages=325–360|series=World Scientific Series on Asia-Pacific Weather and Climate|publisher=WORLD SCIENTIFIC|doi=10.1142/9789814293488_0011|isbn=978-981-4293-47-1|access-date=|last2=Sobel|first2=Adam H.|last3=Barnston|first3=Anthony G.|last4=Klotzbach|first4=Philip J.|archive-date=August 15, 2021|archive-url=https://web.archive.org/web/20210815051723/https://www.worldscientific.com/doi/abs/10.1142/9789814293488_0011|url-status=live}}</ref>


===Influence of climate change===
{{Main|Earth:Tropical cyclones and climate change}}
<!-- The effects of climate change and global warming caused by the burning of fossil fuels on tropical cyclones, is the subject of ongoing debate and research. Evidence has been presented that indicates that tropical cyclone activity has increased as a result of climate change, while others argue that natural variations in tropical cyclone activity on either a regional, annual or inter-decadal scale mask any such increase.
There is no clear consensus on whether global warming is currently having any measurable effect on tropical cyclones, climate models indicate that there may be an increase in tropical cyclone intensity in the future, under continued global warming. However, the models also indicate that tropical cyclone frequency will either remain unchanged or decrease. -->

[[File:1980- Atlantic region category 4 and 5 hurricanes - NYTimes and NOAA.svg |thumb |upright=1.3 |The 20-year average of the number of annual Category 4 and 5 hurricanes in the Atlantic region has approximately doubled since the year 2000.<ref name=NYTimes_20220929>{{cite news |last1=Leonhardt |first1=David |last2=Moses |first2=Claire |last3=Philbrick |first3=Ian Prasad |title=Ian Moves North / Category 4 and 5 Atlantic hurricanes since 1980 |url=https://www.nytimes.com/2022/09/29/briefing/hurricane-ian-storm-climate-change.html |newspaper=The New York Times |date=29 September 2022 |archive-url=https://web.archive.org/web/20220930003545/https://www.nytimes.com/2022/09/29/briefing/hurricane-ian-storm-climate-change.html |archive-date=30 September 2022 |quote=Source: NOAA - Graphic by Ashley Wu, ''The New York Times'' |url-status=live }} ([https://commons.wikimedia.org/wiki/File:1980-_Atlantic_region_category_4_and_5_hurricanes_-_NYTimes_and_NOAA.svg cites for 2022— data])</ref>]]
[[File:202307 Survey - climate change "major factor" in extreme weather - Washington Post.svg |thumb |upright=1.3 |Perceptions differ along political lines, on whether climate change was a "major factor" contributing to various extreme weather events experienced by respondents.<ref name=WashPost_20230823>{{cite news |last1=Ajasa |first1=Amudalat |last2=Clement |first2=Scott |last3=Guskin |first3=Emily |title=Partisans remain split on climate change contributing to more disasters, and on their weather becoming more extreme |url=https://www.washingtonpost.com/climate-environment/2023/08/23/extreme-weather-climate-change-poll/ |newspaper=The Washington Post |date=23 August 2023 |archive-url=https://archive.today/20230823125945/https://www.washingtonpost.com/climate-environment/2023/08/23/extreme-weather-climate-change-poll/ |archive-date=23 August 2023 |url-status=live }}</ref> "Severe storms" includes hurricanes.]]
[[Earth:Climate change|Climate change]] can affect tropical cyclones in a variety of ways: an intensification of rainfall and wind speed, a decrease in overall frequency, an increase in the frequency of very intense storms and a poleward extension of where the cyclones reach maximum intensity are among the possible consequences of human-induced climate change.<ref name=":5">{{Cite journal|last1=Knutson|first1=Thomas|last2=Camargo|first2=Suzana J.|last3=Chan|first3=Johnny C. L.|last4=Emanuel|first4=Kerry|last5=Ho|first5=Chang-Hoi|last6=Kossin|first6=James|last7=Mohapatra|first7=Mrutyunjay|last8=Satoh|first8=Masaki|last9=Sugi|first9=Masato|last10=Walsh|first10=Kevin|last11=Wu|first11=Liguang|date=August 6, 2019|title=Tropical Cyclones and Climate Change Assessment: Part II. Projected Response to Anthropogenic Warming|journal=Bulletin of the American Meteorological Society|volume=101|issue=3|language=en|pages=BAMS–D–18–0194.1|doi=10.1175/BAMS-D-18-0194.1|issn=0003-0007|doi-access=free}}</ref> Tropical cyclones use warm, moist air as their fuel. As climate change is [[Earth:Ocean heat content|warming ocean temperatures]], there is potentially more of this fuel available.<ref>{{Cite web|date=May 18, 2020|title=Major tropical cyclones have become '15% more likely' over past 40 years|url=https://www.carbonbrief.org/major-tropical-cyclones-have-become-15-more-likely-over-past-40-years|access-date=August 31, 2020|website=Carbon Brief|language=en|archive-date=August 8, 2020|archive-url=https://web.archive.org/web/20200808212654/https://www.carbonbrief.org/major-tropical-cyclones-have-become-15-more-likely-over-past-40-years|url-status=live}}</ref> Between 1979 and 2017, there was a global increase in the proportion of tropical cyclones of Category 3 and higher on the [[Earth:Saffir–Simpson scale|Saffir–Simpson scale]]. The trend was most clear in the North Atlantic and in the Southern Indian Ocean. In the North Pacific, tropical cyclones have been moving poleward into colder waters and there was no increase in intensity over this period.<ref>{{Cite journal|last1=Kossin|first1=James P.|last2=Knapp|first2=Kenneth R.|last3=Olander|first3=Timothy L.|last4=Velden|first4=Christopher S.|date=May 18, 2020|title=Global increase in major tropical cyclone exceedance probability over the past four decades|url=https://www.pnas.org/content/pnas/117/22/11975.full.pdf|journal=Proceedings of the National Academy of Sciences|language=en|volume=117|issue=22|pages=11975–11980|doi=10.1073/pnas.1920849117|pmid=32424081|pmc=7275711|bibcode=2020PNAS..11711975K |issn=0027-8424|doi-access=free|access-date=October 6, 2020|archive-date=November 19, 2020|archive-url=https://web.archive.org/web/20201119095015/https://www.pnas.org/content/pnas/117/22/11975.full.pdf|url-status=live}}</ref> With {{Convert|2|C-change|F-change}} warming, a greater percentage (+13%) of tropical cyclones are expected to reach Category 4 and 5 strength.<ref name=":5" /> A 2019 study indicates that climate change has been driving the observed trend of [[Earth:Rapid intensification|rapid intensification]] of tropical cyclones in the Atlantic basin. Rapidly intensifying cyclones are hard to forecast and therefore pose additional risk to coastal communities.<ref>{{Cite book|last1=Collins|first1=M.|title=IPCC Special Report on the Ocean and Cryosphere in a Changing Climate|last2=Sutherland|first2=M.|last3=Bouwer|first3=L.|last4=Cheong|first4=S.-M.|last5=Frölicher|first5=T.|last6=Jacot Des Combes|first6=H.|last7=Koll Roxy|first7=M.|last8=Losada|first8=I. J.|last9=McInnes|first9=K.|year=2019|pages=602|chapter=Chapter 6: Extremes, Abrupt Changes and Managing Risks <!-- ipcc:20200202 -->|display-authors=4|chapter-url=https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|last12=Susanto|last10=Ratter|last11=Rivera-Arriaga|first12=R. D.|last14=Tibig|first11=E.|last13=Swingedouw|first14=L.|first13=D.|first10=B.|access-date=October 6, 2020|archive-date=December 20, 2019|archive-url=https://web.archive.org/web/20191220151131/https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|url-status=live}}</ref>

Warmer air can hold more water vapor: the theoretical maximum water vapor content is given by the [[Physics:Clausius–Clapeyron relation|Clausius–Clapeyron relation]], which yields ≈7% increase in water vapor in the atmosphere per {{Convert|1|C-change|F-change}} warming.<ref>{{cite journal|author1=Thomas R. Knutson|author2=Joseph J. Sirutis|author3=Ming Zhao|year=2015|title=Global Projections of Intense Tropical Cyclone Activity for the Late Twenty-First Century from Dynamical Downscaling of CMIP5/RCP4.5 Scenarios|url=https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1323&context=ccpo_pubs|journal=Journal of Climate|volume=28|issue=18|pages=7203–7224|bibcode=2015JCli...28.7203K|doi=10.1175/JCLI-D-15-0129.1|s2cid=129209836 |access-date=October 6, 2020|archive-date=January 5, 2020|archive-url=https://web.archive.org/web/20200105210405/https://digitalcommons.odu.edu/cgi/viewcontent.cgi?article=1323&context=ccpo_pubs|url-status=live|doi-access=free}}</ref><ref name="knutson 2013">{{cite journal|author=Knutson|display-authors=et al|year=2013|title=Dynamical Downscaling Projections of Late 21st Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-based Scenarios|url=https://www.gfdl.noaa.gov/research_highlight/dynamical-downscaling-projections-of-late-21st-century-atlantic-hurricane-activity-cmip3-and-cmip5-model-based-scenarios/|journal=Journal of Climate|volume=26|issue=17|pages=6591–6617|bibcode=2013JCli...26.6591K|doi=10.1175/JCLI-D-12-00539.1|s2cid=129571840 |access-date=October 6, 2020|archive-date=October 5, 2020|archive-url=https://web.archive.org/web/20201005005313/https://www.gfdl.noaa.gov/research_highlight/dynamical-downscaling-projections-of-late-21st-century-atlantic-hurricane-activity-cmip3-and-cmip5-model-based-scenarios/|url-status=live|doi-access=free}}</ref> All models that were assessed in a 2019 review paper show a future increase of rainfall rates.<ref name=":5" /> Additional [[Earth:Sea level rise|sea level rise]] will increase storm surge levels.<ref name=":6" /><ref name=":4">{{cite news|date=August 29, 2017|title=Hurricane Harvey shows how we underestimate flooding risks in coastal cities, scientists say|url=https://www.washingtonpost.com/news/energy-environment/wp/2017/08/29/hurricane-harvey-shows-how-we-underestimate-flooding-risks-in-coastal-cities-scientists-say|newspaper=The Washington Post|access-date=August 30, 2017|archive-date=August 30, 2017|archive-url=https://web.archive.org/web/20170830031541/https://www.washingtonpost.com/news/energy-environment/wp/2017/08/29/hurricane-harvey-shows-how-we-underestimate-flooding-risks-in-coastal-cities-scientists-say/|url-status=live}}</ref> It is plausible that extreme [[Physics:Wind wave|wind wave]]s see an increase as a consequence of changes in tropical cyclones, further exacerbating storm surge dangers to coastal communities.<ref name=":7" /> The compounding effects from floods, storm surge, and terrestrial flooding (rivers) are projected to increase [[Biology:Effects of global warming|due to global warming]].<ref name=":4" />

There is currently no consensus on how climate change will affect the overall frequency of tropical cyclones.<ref name=":5" /> A majority of [[Earth:Climate model|climate model]]s show a decreased frequency in future projections.<ref name=":7">{{Cite journal|last1=Walsh|first1=K. J. E.|last2=Camargo|first2=S. J.|last3=Knutson|first3=T. R.|last4=Kossin|first4=J.|last5=Lee|first5=T. -C.|last6=Murakami|first6=H.|last7=Patricola|first7=C.|date=December 1, 2019|title=Tropical cyclones and climate change|journal=Tropical Cyclone Research and Review|language=en|volume=8|issue=4|pages=240–250|doi=10.1016/j.tcrr.2020.01.004|bibcode=2019TCRR....8..240W |issn=2225-6032|doi-access=free|hdl=11343/192963|hdl-access=free}}</ref> For instance, a 2020 paper comparing nine high-resolution climate models found robust decreases in frequency in the Southern Indian Ocean and the Southern Hemisphere more generally, while finding mixed signals for Northern Hemisphere tropical cyclones.<ref>{{Cite journal|last1=Roberts|first1=Malcolm John|last2=Camp|first2=Joanne|last3=Seddon|first3=Jon|last4=Vidale|first4=Pier Luigi|last5=Hodges|first5=Kevin|last6=Vannière|first6=Benoît|last7=Mecking|first7=Jenny|last8=Haarsma|first8=Rein|last9=Bellucci|first9=Alessio|last10=Scoccimarro|first10=Enrico|last11=Caron|first11=Louis-Philippe|year=2020|title=Projected Future Changes in Tropical Cyclones Using the CMIP6 HighResMIP Multimodel Ensemble|journal=Geophysical Research Letters|language=en|volume=47|issue=14|pages=e2020GL088662|doi=10.1029/2020GL088662|pmid=32999514|pmc=7507130|bibcode=2020GeoRL..4788662R|s2cid=221972087|issn=1944-8007}}</ref> Observations have shown little change in the overall frequency of tropical cyclones worldwide,<ref>{{Cite web|title=Hurricanes and Climate Change|url=https://www.ucsusa.org/global-warming/science-and-impacts/impacts/hurricanes-and-climate-change.html|access-date=September 29, 2019|website=Union of Concerned Scientists|language=en|archive-date=September 24, 2019|archive-url=https://web.archive.org/web/20190924043720/https://www.ucsusa.org/global-warming/science-and-impacts/impacts/hurricanes-and-climate-change.html|url-status=live}}</ref> with increased frequency in the North Atlantic and central Pacific, and significant decreases in the southern Indian Ocean and western North Pacific.<ref>{{Cite journal|last1=Murakami|first1=Hiroyuki|last2=Delworth|first2=Thomas L.|last3=Cooke|first3=William F.|last4=Zhao|first4=Ming|last5=Xiang|first5=Baoqiang|last6=Hsu|first6=Pang-Chi|year=2020|title=Detected climatic change in global distribution of tropical cyclones|journal=Proceedings of the National Academy of Sciences|language=en|volume=117|issue=20|pages=10706–10714|doi=10.1073/pnas.1922500117|issn=0027-8424|pmid=32366651|pmc=7245084|bibcode=2020PNAS..11710706M |doi-access=free}}</ref> There has been a poleward expansion of the latitude at which the maximum intensity of tropical cyclones occurs, which may be associated with climate change.<ref>{{cite journal|author1=James P. Kossin|author2=Kerry A. Emanuel|author3=Gabriel A. Vecchi|year=2014|title=The poleward migration of the location of tropical cyclone maximum intensity|journal=Nature|volume=509|issue=7500|pages=349–352|bibcode=2014Natur.509..349K|doi=10.1038/nature13278|pmid=24828193|hdl-access=free|hdl=1721.1/91576|s2cid=4463311}}</ref> In the North Pacific, there may also have been an eastward expansion.<ref name=":6">{{Cite book|last1=Collins|first1=M.|title=IPCC Special Report on the Ocean and Cryosphere in a Changing Climate|last2=Sutherland|first2=M.|last3=Bouwer|first3=L.|last4=Cheong|first4=S.-M.|last5=Frölicher|first5=T.|last6=Jacot Des Combes|first6=H.|last7=Koll Roxy|first7=M.|last8=Losada|first8=I. J.|last9=McInnes|first9=K.|year=2019|pages=603|chapter=Chapter 6: Extremes, Abrupt Changes and Managing Risks|ref={{harvid|IPCC SROCC Ch6|2019}} <!-- ipcc:20200202 -->|display-authors=4|chapter-url=https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|last12=Susanto|last10=Ratter|last11=Rivera-Arriaga|first12=R. D.|last14=Tibig|first11=E.|last13=Swingedouw|first14=L.|first13=D.|first10=B.|access-date=October 6, 2020|archive-date=December 20, 2019|archive-url=https://web.archive.org/web/20191220151131/https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|url-status=live}}</ref> Between 1949 and 2016, there was a slowdown in tropical cyclone translation speeds. It is unclear still to what extent this can be attributed to climate change: climate models do not all show this feature.<ref name=":7"/>

A study review article published in 2021 concluded that the geographic range of tropical cyclones will probably expand poleward in response to climate warming of the Hadley circulation.<ref>{{cite journal |last1=Studholme |first1=Joshua |last2=Fedorov |first2=Alexey V. |last3=Gulev |first3=Sergey K. |last4=Emanuel |first4=Kerry |last5=Hodges |first5=Kevin |date=December 29, 2021 |title=Poleward expansion of tropical cyclone latitudes in warming climates |url=https://www.nature.com/articles/s41561-021-00859-1 |url-status=live |journal=[[Earth:Nature Geoscience|Nature Geoscience]] |volume=15 |pages=14–28 |doi=10.1038/s41561-021-00859-1 |s2cid=245540084 |archive-url=https://web.archive.org/web/20220104110552/https://www.nature.com/articles/s41561-021-00859-1 |archive-date=January 4, 2022 |access-date=January 4, 2022}}</ref>

==Observation and forecasting==

===Observation===
{{Main|Earth:Tropical cyclone observation}}
[[File:Isidore091902-p3sunset.jpg|right|thumb|upright=1.15|Sunset view of Hurricane Isidore's rainbands photographed at {{convert|7000|ft|m|abbr=on|order=flip}}|alt=Aerial view of storm clouds]]
[[File:NOAA Lockheed WP-3D Orion "Hurricane Hunter" (N42RF) at SENEX Air Quality-Climate Research Study (9119691512).jpg|thumb|"[[Earth:Hurricane hunters|Hurricane Hunter]]" – WP-3D Orion is used to go into the eye of a hurricane for data collection and measurements purposes.|alt=Head-on view of an airplane]]
Historically, tropical cyclones have occurred around the world for thousands of years, with one of the earliest tropical cyclones on record estimated to have occurred in Western Australia in around 4000 BC.<ref name="6000 WA" /> However, before satellite imagery became available during the 20th century, there was no way to detect a tropical cyclone unless it impacted land or a ship encountered it by chance.<ref name="Global Guide 2017" />

Intense tropical cyclones pose a particular observation challenge, as they are a dangerous oceanic phenomenon, and [[Engineering:Weather station|weather station]]s, being relatively sparse, are rarely available on the site of the storm itself. In general, surface observations are available only if the storm is passing over an island or a coastal area, or if there is a nearby ship. Real-time measurements are usually taken in the periphery of the cyclone, where conditions are less catastrophic and its true strength cannot be evaluated. For this reason, there are teams of meteorologists that move into the path of tropical cyclones to help evaluate their strength at the point of landfall.<ref name="FCMP">{{cite web|url=http://users.ce.ufl.edu/~fcmp/overview/overview.htm|author=Florida Coastal Monitoring Program|title=Project Overview|access-date=March 30, 2006|publisher=[[Organization:University of Florida|University of Florida]]|archive-url = https://web.archive.org/web/20060503084406/http://users.ce.ufl.edu/~fcmp/overview/overview.htm |archive-date = May 3, 2006|url-status=dead}}</ref>

Tropical cyclones are tracked by [[Engineering:Weather satellite|weather satellite]]s capturing [[Physics:Visible light|visible]] and [[Physics:Infrared|infrared]] images from space, usually at half-hour to quarter-hour intervals. As a storm approaches land, it can be observed by land-based [[Physics:Pulse-Doppler radar|Doppler]] [[Earth:Weather radar|weather radar]]. Radar plays a crucial role around landfall by showing a storm's location and intensity every several minutes.<ref name="CPHC">{{cite web|date=December 9, 2006|title=Observations|url=http://www.prh.noaa.gov/cphc/HAW/observations.php|url-status=dead|archive-url=https://web.archive.org/web/20120212231044/http://www.prh.noaa.gov/cphc/HAW/observations.php|archive-date=February 12, 2012|access-date=May 7, 2009|publisher=Central Pacific Hurricane Center}}</ref> Other satellites provide information from the perturbations of [[Engineering:Global Positioning System|GPS]] signals, providing thousands of snapshots per day and capturing atmospheric temperature, pressure, and moisture content.<ref>{{Cite web|date=June 1, 2020|title=NOAA harnessing the power of new satellite data this hurricane season|url=https://www.noaa.gov/media-release/noaa-harnessing-power-of-new-satellite-data-hurricane-season|access-date=March 25, 2021|website=National Oceanic and Atmospheric Administration|archive-date=March 18, 2021|archive-url=https://web.archive.org/web/20210318001639/https://www.noaa.gov/media-release/noaa-harnessing-power-of-new-satellite-data-hurricane-season|url-status=live}}</ref>

[[Biology:In situ|In situ]] measurements, in real-time, can be taken by sending specially equipped reconnaissance flights into the cyclone. In the Atlantic basin, these flights are regularly flown by United States government [[Earth:Hurricane hunters|hurricane hunters]].<ref name="Hurricane Hunters">{{cite web|author=403rd Wing|url=http://www.hurricanehunters.com|title=The Hurricane Hunters|publisher=53rd Weather Reconnaissance Squadron|access-date=March 30, 2006|archive-url=https://web.archive.org/web/20120530232904/http://www.hurricanehunters.com/|archive-date=May 30, 2012|url-status=live}}</ref> These aircraft fly directly into the cyclone and take direct and remote-sensing measurements. The aircraft also launch GPS dropsondes inside the cyclone. These sondes measure temperature, humidity, pressure, and especially winds between flight level and the ocean's surface. A new era in hurricane observation began when a remotely piloted Aerosonde, a small drone aircraft, was flown through Tropical Storm Ophelia as it passed Virginia's eastern shore during the 2005 hurricane season. A similar mission was also completed successfully in the western Pacific Ocean.<ref name="SunHerald">{{cite news|author=Lee, Christopher|title=Drone, Sensors May Open Path Into Eye of Storm|url=https://www.washingtonpost.com/wp-dyn/content/article/2007/10/07/AR2007100700971_pf.html|newspaper=The Washington Post|access-date=February 22, 2008|archive-url=https://web.archive.org/web/20121111093844/http://www.washingtonpost.com/wp-dyn/content/article/2007/10/07/AR2007100700971_pf.html|archive-date=November 11, 2012|url-status=live}}</ref>

[[File:NHC Atlantic Forecast Error Trends.png|thumb|upright=1.15|A general decrease in error trends in tropical cyclone path prediction is evident since the 1970s|alt=Track errors plotted over time]]

===Forecasting===
High-speed computers and sophisticated simulation software allow forecasters to produce computer models that predict tropical cyclone tracks based on the future position and strength of high- and low-pressure systems. Combining forecast models with increased understanding of the forces that act on tropical cyclones, as well as with a wealth of data from Earth-orbiting satellites and other sensors, scientists have increased the accuracy of track forecasts over recent decades.<ref name="NHC forecast verifications models">{{cite web|author=National Hurricane Center|url=http://www.nhc.noaa.gov/verification/verify6.shtml?#FIG1|work=National Hurricane Center Forecast Verification|title=Annual average model track errors for Atlantic basin tropical cyclones for the period 1994–2005, for a homogeneous selection of "early" models|access-date=November 30, 2006|publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]|date=May 22, 2006|archive-url=https://web.archive.org/web/20120510225232/http://www.nhc.noaa.gov/verification/verify6.shtml#FIG1|archive-date=May 10, 2012|url-status=live}}</ref> However, scientists are not as skillful at predicting the intensity of tropical cyclones.<ref name="NHC forecast verifications Atlantic">{{cite web|author=National Hurricane Center|work=National Hurricane Center Forecast Verification|url=http://www.nhc.noaa.gov/verification/verify5.shtml?|title=Annual average official track errors for Atlantic basin tropical cyclones for the period 1989–2005, with least-squares trend lines superimposed|access-date=November 30, 2006|publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]|date=May 22, 2006|author-link=National Hurricane Center|archive-url=https://web.archive.org/web/20120510225314/http://www.nhc.noaa.gov/verification/verify5.shtml|archive-date=May 10, 2012|url-status=live}}</ref> The lack of improvement in intensity forecasting is attributed to the complexity of tropical systems and an incomplete understanding of factors that affect their development. New tropical cyclone position and forecast information is available at least every six hours from the various warning centers.<ref name="WMO RSMC list">{{cite web|work=Tropical Cyclone Program (TCP)|publisher=[[Organization:World Meteorological Organization|World Meteorological Organization]]|title=Regional Specialized Meteorological Center|date=April 25, 2006|access-date=November 5, 2006|url=http://severe.worldweather.wmo.int/rsmcs.html|archive-url=https://web.archive.org/web/20100814135352/http://severe.worldweather.wmo.int/rsmcs.html|archive-date=August 14, 2010|url-status=live}}</ref><ref>{{cite web|url=http://www.met.gov.fj/services.php|title=Services|author=Fiji Meteorological Service|access-date=June 4, 2017|year=2017|archive-url=https://web.archive.org/web/20170618023828/http://www.met.gov.fj/services.php|archive-date=June 18, 2017|url-status=live}}</ref><ref>{{cite web|url=http://www.usno.navy.mil/JTWC/products-and-services-notice|title=Products and Service Notice|author=Joint Typhoon Warning Center|publisher=United States Navy|year=2017|access-date=June 4, 2017|archive-url=https://web.archive.org/web/20170609092158/http://www.usno.navy.mil/JTWC/products-and-services-notice|archive-date=June 9, 2017|url-status=live}}</ref><ref name="NHCprod">{{cite web|url=http://www.nhc.noaa.gov/pdf/NHC_Product_Description.pdf|title=National Hurricane Center Product Description Document: A User's Guide to Hurricane Products|author=National Hurricane Center|date=March 2016|access-date=June 3, 2017|publisher=National Oceanic and Atmospheric Administration|archive-url=https://web.archive.org/web/20170617023135/http://www.nhc.noaa.gov/pdf/NHC_Product_Description.pdf|archive-date=June 17, 2017|url-status=live}}</ref><ref>{{cite web|url=http://www.jma.go.jp/jma/jma-eng/jma-center/rsmc-hp-pub-eg/advisory.html|title=Notes on RSMC Tropical Cyclone Information|publisher=Japan Meteorological Agency|year=2017|access-date=June 4, 2017|archive-url=https://web.archive.org/web/20170319230044/http://www.jma.go.jp/jma/jma-eng/jma-center/rsmc-hp-pub-eg/advisory.html|archive-date=March 19, 2017|url-status=live}}</ref>
===Geopotential height===
{{main|Geopotential height}}
In meteorology, geopotential heights are used when creating forecasts and analyzing pressure systems. Geopotential heights represent the estimate of the real height of a pressure system above the average sea level.<ref name="Geo Height">{{cite web |title=Geopotential Height |url=https://www.weather.gov/source/zhu/ZHU_Training_Page/Miscellaneous/Heights_Thicknesses/thickness_temperature.htm |publisher=National Weather Service |access-date=October 7, 2022 |archive-date=March 24, 2022 |archive-url=https://web.archive.org/web/20220324054919/https://www.weather.gov/source/zhu/ZHU_Training_Page/Miscellaneous/Heights_Thicknesses/thickness_temperature.htm |url-status=live }}</ref> Geopotential heights for weather are divided up into several levels. The lowest geopotential height level is {{convert|850|hPa|inHg|sigfig=4|abbr=on}}, which represents the lowest {{convert|5000|ft|m|abbr=on|disp=flip}} of the atmosphere. The moisture content, gained by using either the relative humidity or the precipitable water value, is used in creating forecasts for precipitation.<ref>{{cite web |title=Constant Pressure Charts: 850 mb |url=https://www.weather.gov/jetstream/850mb |publisher=National Weather Service |access-date=October 7, 2022 |archive-date=May 4, 2022 |archive-url=https://web.archive.org/web/20220504135947/https://www.weather.gov/jetstream/850mb |url-status=live }}</ref> The next level, {{convert|700|hPa|inHg|sigfig=4|abbr=on}}, is at a height of {{convert|7700–10500|ft|m|abbr=on|disp=flip}}; 700 hPa is regarded as the highest point in the lower atmosphere. At this layer, both vertical movement and moisture levels are used to locate and create forecasts for precipitation.<ref>{{cite web |title=Constant Pressure Charts: 700 mb |url=https://www.weather.gov/jetstream/300mb |publisher=National Weather Service |access-date=October 7, 2022 |archive-date=June 29, 2022 |archive-url=https://web.archive.org/web/20220629223346/https://www.weather.gov/jetstream/300mb |url-status=live }}</ref> The middle level of the atmosphere is at {{convert|500|hPa|inHg|sigfig=4|abbr=on}} or a height of {{convert|16000–20000|ft|m|abbr=on|disp=flip}}. The 500 hPa level is used for measuring atmospheric vorticity, commonly known as the spin of air. The relative humidity is also analyzed at this height in order to establish where precipitation is likely to materialize.<ref>{{cite web |title=Constant Pressure Charts: 500 mb |url=https://www.weather.gov/jetstream/500mb |publisher=National Weather Service |access-date=October 7, 2022 |archive-date=May 21, 2022 |archive-url=https://web.archive.org/web/20220521143701/https://www.weather.gov/jetstream/500mb |url-status=live }}</ref> The next level occurs at {{convert|300|hPa|inHg|sigfig=4|abbr=on}} or a height of {{convert|27000–32000|ft|m|abbr=on|disp=flip}}.<ref>{{cite web |title=Constant Pressure Charts: 300 mb |url=https://www.weather.gov/jetstream/300mb |publisher=National Weather Service |access-date=October 7, 2022 |archive-date=October 7, 2022 |archive-url=https://web.archive.org/web/20221007215843/https://www.weather.gov/jetstream/300mb |url-status=live }}</ref> The top-most level is located at {{convert|200|hPa|inHg|sigfig=4|abbr=on}}, which corresponds to a height of {{convert|35000–41000|ft|m|abbr=on|disp=flip}}. Both the 200 and 300 hPa levels are mainly used to locate the jet stream.<ref>{{cite web |title=Constant Pressure Charts: 200 mb |url=https://www.weather.gov/jetstream/200mb |publisher=National Weather Service |access-date=October 7, 2022 |archive-date=August 5, 2022 |archive-url=https://web.archive.org/web/20220805062247/https://www.weather.gov/jetstream/200mb |url-status=live }}</ref>

== Society and culture ==

=== Preparations ===
{{main|Earth:Tropical cyclone preparedness|Engineering:Tropical cyclone engineering}}
[[File:Hurricane_Route_sign_Tulane_Avenue_floodlines.jpg|right|thumb|267x267px|Evacuation route sign on Tulane Avenue in New Orleans shows lines from long standing floodwaters after Hurricane Katrina]]
Ahead of the formal season starting, people are urged to [[Earth:Tropical cyclone preparedness|prepare for the effects of a tropical cyclone]] by politicians and weather forecasters, amongst others. They prepare by determining their risk to the different types of weather, tropical cyclones cause, checking their insurance coverage and emergency supplies, as well as determining where to evacuate to if needed.<ref name="ReadyGov Preparedness">{{cite web |date=February 18, 2021 |title=Hurricane Seasonal Preparedness Digital Toolkit |url=https://www.ready.gov/ru/node/5121 |url-status=live |archive-url=https://web.archive.org/web/20210321121554/https://www.ready.gov/ru/node/5121 |archive-date=March 21, 2021 |access-date=April 6, 2021 |publisher=Ready.gov}}</ref><ref name="Gray et al. 2019">{{cite conference |last1=Gray |first1=Briony |last2=Weal |first2=Mark |last3=Martin |first3=David |year=2019 |title=Proceedings of the 52nd Hawaii International Conference on System Sciences |conference=52nd Hawaii International Conference on System Sciences |publisher=University of Hawaii |doi=10.24251/HICSS.2019.338 |isbn=978-0-9981331-2-6 |doi-access=free |hdl-access=free |chapter=The Role of Social Networking in Small Island Communities: Lessons from the 2017 Atlantic Hurricane Season |hdl=10125/59718}}</ref><ref name="Morrissey and Reser 2003">{{cite journal |last1=Morrissey |first1=Shirley A. |last2=Reser |first2=Joseph P. |date=May 1, 2003 |title=Evaluating the Effectiveness of Psychological Preparedness Advice in Community Cyclone Preparedness Materials |url=https://search.informit.org/doi/10.3316/informit.281780145360789 |url-status=live |journal=The Australian Journal of Emergency Management |volume=18 |issue=2 |pages=46–61 |archive-url=https://web.archive.org/web/20220523221113/https://search.informit.org/doi/10.3316/informit.281780145360789 |archive-date=May 23, 2022 |access-date=April 6, 2021}}</ref> When a tropical cyclone develops and is forecast to impact land, each member nation of the [[Organization:World Meteorological Organization|World Meteorological Organization]] issues various watches and warnings to cover the expected effects.<ref name="WMO TC">{{cite web |date=April 8, 2020 |title=Tropical Cyclones |url=https://public-old.wmo.int/en/our-mandate/focus-areas/natural-hazards-and-disaster-risk-reduction/tropical-cyclones |url-status=dead |archive-url=https://web.archive.org/web/20231218180931/https://public-old.wmo.int/en/our-mandate/focus-areas/natural-hazards-and-disaster-risk-reduction/tropical-cyclones |archive-date=December 18, 2023 |access-date=April 6, 2021 |publisher=World Meteorological Organization}}</ref> However, there are some exceptions with the United States National Hurricane Center and Fiji Meteorological Service responsible for issuing or recommending warnings for other nations in their area of responsibility.<ref name="AboutFMS">{{cite web |title=Fiji Meteorological Services |url=http://www.moit.gov.fj/about-us/27-departments/fiji-meteorological-services |url-status=live |archive-url=https://web.archive.org/web/20210814123025/http://www.moit.gov.fj/about-us/27-departments/fiji-meteorological-services |archive-date=August 14, 2021 |access-date=April 6, 2021 |website=Ministry of Infrastructure & Meteorological Services |publisher=Ministry of Infrastructure & Transport}}</ref><ref name="About NHC">{{cite web |title=About the National Hurricane Center |url=https://www.nhc.noaa.gov/aboutintro.shtml |url-status=live |archive-url=https://web.archive.org/web/20201012163706/https://www.nhc.noaa.gov/aboutintro.shtml |archive-date=October 12, 2020 |access-date=April 6, 2021 |publisher=National Hurricane Center |location=Miami, Florida}}</ref><ref name="RAIV2017">{{cite book |url=https://library.wmo.int/doc_num.php?explnum_id=3781 |title=Regional Association IV – Hurricane Operational Plan for NOrth America, Central America and the Caribbean |date=2017 |publisher=World Meteorological Organization |isbn=9789263111630 |format=PDF |access-date=April 6, 2021 |archive-url=https://web.archive.org/web/20201114181542/https://library.wmo.int/doc_num.php?explnum_id=3781 |archive-date=November 14, 2020 |url-status=live}}</ref>{{rp|2–4}}

An important decision in individual preparedness is determining if and when to evacuate an area that will be affected by a tropical cyclone.<ref>{{Cite web |title=National Hurricane Center - "Be Prepared" |url=http://www.nhc.noaa.gov/HAW2/english/disaster_prevention.shtml |accessdate=9 November 2023}}</ref> [[Earth:Tropical cyclone tracking chart|Tropical cyclone tracking charts]] allow people to track ongoing systems to form their own opinions regarding where the storms are going and whether or not they need to prepare for the system being tracked, including possible evacuation.  This continues to be encouraged by the [[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]] and National Hurricane Center.<ref name="FTH">{{cite web |author=National Ocean Service |date=2016-09-07 |title=Follow That Hurricane! |url=http://oceanservice.noaa.gov/education/for_fun/FollowthatHurricane.pdf |access-date=2017-06-02 |publisher=[[Organization:National Oceanic and Atmospheric Administration|National Oceanic and Atmospheric Administration]]}}</ref>

=== Response ===
{{main|Earth:Tropical cyclone response}}
[[File:DSS Supports Hurricane Dorian Relief Efforts in the Bahamas (49091289561).jpg|thumb|Relief efforts for Hurricane Dorian in the Bahamas|alt=View of tropical cyclone damage from a helicopter]]
Hurricane response is the disaster response after a hurricane. Activities performed by hurricane responders include assessment, restoration, and demolition of buildings; removal of [[Physics:Debris|debris]] and waste; repairs to land-based and maritime [[Physics:Infrastructure|infrastructure]]; and public health services including search and rescue operations.<ref>{{Cite web |year=2005 |title=OSHA's Hazard Exposure and Risk Assessment Matrix for Hurricane Response and Recovery Work: List of Activity Sheets |url=https://www.osha.gov/SLTC/etools/hurricane/sheets.html |url-status=live |archive-url=https://web.archive.org/web/20180929041351/https://www.osha.gov/SLTC/etools/hurricane/sheets.html |archive-date=September 29, 2018 |access-date=September 25, 2018 |website=U.S. [[Organization:Occupational Safety and Health Administration|Occupational Safety and Health Administration]] |language=en-US}}</ref> Hurricane response requires coordination between federal, tribal, state, local, and private entities.<ref>{{Cite web |title=Before You Begin – The Incident Command System (ICS) |url=https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Before-You-Begin.aspx |url-status=dead |archive-url=https://web.archive.org/web/20180929041449/https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Before-You-Begin.aspx |archive-date=September 29, 2018 |access-date=September 26, 2018 |website=American Industrial Hygiene Association |language=en-us}}</ref> According to the National Voluntary Organizations Active in Disaster, potential response volunteers should affiliate with established organizations and should not self-deploy, so that proper training and support can be provided to mitigate the danger and stress of response work.<ref>{{Cite web |title=Volunteer |url=https://www.nvoad.org/howtohelp/volunteer-3/ |url-status=live |archive-url=https://web.archive.org/web/20180929041523/https://www.nvoad.org/howtohelp/volunteer-3/ |archive-date=September 29, 2018 |access-date=September 25, 2018 |website=National Voluntary Organizations Active in Disaster |language=en-US}}</ref>

Hurricane responders face many hazards. Hurricane responders may be exposed to chemical and biological contaminants including stored chemicals, [[Earth:Sewage|sewage]], human remains, and [[Biology:Indoor mold|mold]] growth encouraged by flooding,<ref name=":0">{{Cite journal |year=2017 |title=Hurricane Key Messages for Employers, Workers and Volunteers |url=https://www.hsdl.org/?abstract&did=815992 |url-status=live |archive-url=https://web.archive.org/web/20181124162356/https://www.hsdl.org/?abstract&did=815992 |archive-date=November 24, 2018 |access-date=September 24, 2018 |website=U.S. [[Organization:National Institute for Occupational Safety and Health|National Institute for Occupational Safety and Health]]}}</ref><ref name=":2">{{Cite web |title=Hazardous Materials and Conditions |url=https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Hazardous-Materials.aspx |url-status=dead |archive-url=https://web.archive.org/web/20180929080011/https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Hazardous-Materials.aspx |archive-date=September 29, 2018 |access-date=September 26, 2018 |website=American Industrial Hygiene Association |language=en-us}}</ref><ref>{{Cite web |title=Mold and Other Microbial Growth |url=https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Mold-and-Other-Microbial-Growth.aspx |url-status=dead |archive-url=https://web.archive.org/web/20180929041433/https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Mold-and-Other-Microbial-Growth.aspx |archive-date=September 29, 2018 |access-date=September 26, 2018 |website=American Industrial Hygiene Association |language=en-us}}</ref> as well as [[Chemistry:Asbestos|asbestos]] and [[Chemistry:Lead|lead]] that may be present in older buildings.<ref name=":2" /><ref name=":1">{{Cite web |year=2005 |title=OSHA's Hazard Exposure and Risk Assessment Matrix for Hurricane Response and Recovery Work: Recommendations for General Hazards Commonly Encountered during Hurricane Response and Recovery Operations |url=https://www.osha.gov/SLTC/etools/hurricane/recommendations.html#encounter |url-status=live |archive-url=https://web.archive.org/web/20180929041128/https://www.osha.gov/SLTC/etools/hurricane/recommendations.html#encounter |archive-date=September 29, 2018 |access-date=September 25, 2018 |website=U.S. Occupational Safety and Health Administration |language=en-US}}</ref> Common injuries arise from [[Medicine:Falling (accident)|falls]] from heights, such as from a ladder or from level surfaces; from [[Physics:Electrocution|electrocution]] in flooded areas, including from [[Engineering:Backfeeding|backfeed]] from portable generators; or from motor vehicle accidents.<ref name=":0" /><ref name=":1" /><ref>{{Cite web |title=Electrical Hazards |url=https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Electrical-Hazards-Floods.aspx |url-status=dead |archive-url=https://web.archive.org/web/20180929041458/https://www.aiha.org/publications-and-resources/HealthandSafetyIssuesinNaturalDisasters/Pages/Electrical-Hazards-Floods.aspx |archive-date=September 29, 2018 |access-date=September 26, 2018 |website=American Industrial Hygiene Association |language=en-us}}</ref> [[Chemistry:Shift work|Long and irregular shifts]] may lead to [[Medicine:Sleep deprivation|sleep deprivation]] and [[Medicine:Fatigue|fatigue]], increasing the risk of injuries, and workers may experience [[Medicine:Posttraumatic stress disorder|mental stress associated with a traumatic incident]]. Additionally, heat stress is a concern as workers are often exposed to hot and humid temperatures, wear protective clothing and equipment, and have physically difficult tasks.<ref name=":0" /><ref name=":1" />

==See also==
*[[Physics:Cyclone|Cyclone]]
*Tropical cyclones by year
* Tropical cyclones in {{CURRENTYEAR}}
* Atlantic hurricane season
* Pacific hurricane season
* Pacific typhoon season
* North Indian Ocean cyclone season
* {{#time:Y}}–{{#time:y|+1 year}}|{{#time:Y|-1 year}}–{{#time:y}}}} South-West Indian Ocean cyclone season
* {{#time:Y}}–{{#time:y|+1 year}}|{{#time:Y|-1 year}}–{{#time:y}}}} Australian region cyclone season
* {{#time:Y}}–{{#time:y|+1 year}}|{{#time:Y|-1 year}}–{{#time:y}}}} South Pacific cyclone season

==References==
{{notelist}}
{{Reflist}}

==External links==
{{Wikivoyage|Cyclones}}

* [http://www.nhc.noaa.gov/ United States National Hurricane Center]&nbsp;– North Atlantic, Eastern Pacific
* [https://web.archive.org/web/20110923144245/http://www.prh.noaa.gov/hnl/cphc/ United States Central Pacific Hurricane Center]&nbsp;– Central Pacific
* [http://www.jma.go.jp/en/typh/ Japan Meteorological Agency]&nbsp;– Western Pacific
* [http://www.rsmcnewdelhi.imd.gov.in/index.php?lang=en India Meteorological Department]&nbsp;– Indian Ocean
* [http://www.meteo.fr/temps/domtom/La_Reunion/ Météo-France&nbsp;– La Reunion]&nbsp;– South Indian Ocean from 30°E to 90°E
* [http://meteo.bmkg.go.id/siklon Indonesian Meteorological Department]&nbsp;– South Indian Ocean from 90°E to 125°E, north of 10°S
* [http://www.bom.gov.au/cyclone/ Australian Bureau of Meteorology]&nbsp;– South Indian Ocean and South Pacific Ocean from 90°E to 160°E
* [http://www.pngmet.gov.pg/ Papua New Guinea National Weather Service]&nbsp;– South Pacific east of 160°E, north of 10°S
* [http://www.met.gov.fj/ Fiji Meteorological Service]&nbsp;– South Pacific west of 160°E, north of 25° S
* [http://metservice.com/ MetService New Zealand]&nbsp;– South Pacific west of 160°E, south of 25°S

{{Cyclones}}
{{Nature}}

{{DEFAULTSORT:Tropical Cyclone}}
[[Category:Tropical cyclones| ]]
[[Category:Tropical cyclone meteorology| ]]
[[Category:Meteorological phenomena]]
[[Category:Types of cyclone]]
[[Category:Vortices]]
[[Category:Weather hazards]]
[[Category:Storm]]

{{Sourceattribution|Tropical cyclone}}