Earth:Hair ice
Hair ice, also known as ice wool or frost beard, is a type of ice that forms on dead wood and takes the shape of fine, silky hair.[1] It is somewhat uncommon, and has been reported mostly at latitudes between 45 and 55 °N in broadleaf forests.[1][2] The meteorologist (and discoverer of continental drift) Alfred Wegener described hair ice on wet dead wood in 1918,[3] assuming some specific fungi as the catalyst, a theory mostly confirmed by Gerhart Wagner and Christian Mätzler in 2005.[4][5][6] In 2015, the fungus Exidiopsis effusa was identified as key to the formation of hair ice.[1]
Formation
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Hair ice forms on moist, rotting wood from broadleaf trees when temperatures are slightly under 0 °C (32 °F) and the air is humid.[1] The hairs appear to root at the mouth of wood rays (never on the bark), and their thickness is similar to the diameter of the wood ray channels.[1] A piece of wood that produces hair ice once may continue to produce it over several years.[1]
Each of the smooth, silky hairs has a diameter of about 0.02 mm (0.0008 in) and a length of up to 20 cm (8 in).[1] The hairs are brittle, but take the shape of curls and waves.[1] They can maintain their shape for hours and sometimes days.[1] This long lifetime indicates that something is preventing the small ice crystals from recrystallizing into larger ones, since recrystallization normally occurs very quickly at temperatures near 0 °C (32 °F).[1]
In the year 2015, German and Swiss scientists identified the fungus Exidiopsis effusa as key to the formation of hair ice.[1] The fungus was found on every hair ice sample examined by the researchers, and disabling the fungus with fungicide or hot water prevented hair ice formation.[1] The fungus shapes the ice into fine hairs through an uncertain mechanism and likely stabilizes it by providing a recrystallization inhibitor similar to antifreeze proteins.[1][2]
See also
- Frost flower
- Hoarfrost
- Needle ice
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 "Evidence for biological shaping of hair ice.". Biogeosciences 12 (14): 4261–4273. 2015. doi:10.5194/bg-12-4261-2015. Bibcode: 2015BGeo...12.4261H. http://www.biogeosciences.net/12/4261/2015/bg-12-4261-2015.pdf.
- ↑ 2.0 2.1 European Geosciences Union (22 July 2015). "Press Release: Fungus shapes hair ice – Researchers identify fungus responsible for peculiar ice filaments that grow on dead wood". http://www.egu.eu/news/180/fungus-shapes-hair-ice-researchers-identify-fungus-responsible-for-peculiar-ice-filaments-that-grow-on-dead-wood/.
- ↑ Alfred Wegener: Haareis auf morschem Holz. Die Naturwissenschaften 6/1, 1918. S. 598–601.
- ↑ Gerhart Wagner: Haareis – eine seltene winterliche Naturerscheinung. Was haben Pilze damit zu tun? SZP/BSM 2005.
- ↑ Gerhart Wagner, Christian Mätzler: Haareis auf morschem Laubholz als biophysikalisches Phänomen. Forschungsbericht Nr. 2008-05-MW. Universität Bern. 2008. (PDF-Download )
- ↑ Gerhart Wagner, Christian Mätzler: Haareis - Ein seltenes biophysikalisches Phänomen im Winter. Naturwissenschaftliche Rundschau 62(3), S. 117–123 (2009), ISSN 0028-1050
External links
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https://www.livescience.com/hair-ice-ireland-fungus.html
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