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.[1]

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[2]
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.

References

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  1. ^ Turner, D. Bruce (1964). "A Diffusion Model for an Urban Area". Journal of Applied Meteorology. 3 (1): 83–91. Bibcode:1964JApMe...3...83T. doi:10.1175/1520-0450(1964)003<0083:ADMFAU>2.0.CO;2. Retrieved July 10, 2021.
  2. ^ Turner, D. Bruce (1961). "Relationships Between 24-Hour Mean Air Quality Measurements and Meteorological Factors in Nashville, Tennessee". Journal of the Air Pollution Control Association. 11 (10): 483–489. doi:10.1080/00022470.1961.10468029. PMID 13923192. Retrieved 2021-07-10.