Earth:Turner stability class

The Turner stability class or Turner stability index is a classification of atmospheric stability over an interval of time based on measurements of surface-level wind speed and net solar radiation. Classes range from 1 (most unstable) to 7 (most stable). The Turner stability class system was devised by D. B. Turner as a modification of the Pasquill stability class system. The following table is used to determine the Turner stability class for a given wind speed and net solar radiation:

Determining the Turner stability class requires first computing the net solar radiation index according to the procedure outlined in Turner (1961) and Turner (1964).

Turner Stability Class

Wind speed (knots)	Net radiation index
	4	3	2	1	0	-1	-2
0, 1	1	1	2	3	4	6	7
2, 3	1	2	2	3	4	6	7
4, 5	1	2	3	4	4	5	6
6	2	2	3	4	4	5	6
7	2	2	3	4	4	4	5
8, 9	2	3	3	4	4	4	5
10	3	3	4	4	4	4	5
11	3	3	4	4	4	4	4
≥ 12	3	4	4	4	4	4	4

The net radiation index is determined by following a procedure (see flowchart) that takes into account the cloud cover, ceiling height, and solar altitude.