The Pasquill Stability Classes—Estimation of

The Monin-Obukhov length L is not a parameter that is routinely measured. Recognizing the need for a readily usable way to define atmospheric stability based on routine observations, Pasquill (1961) proposed a discrete atmospheric stability classification scheme that was later modified by Turner (1969). The scheme relies on observations of near-surface (10 m) wind, solar radiation, and cloudiness. If these 

The neutral category D should be used, regardless of windspeed, for overcast conditions during day or night. 

FIGURE 16.8 A relationship between Monin-Obukhov length L and roughness height for various Pasquill stability classes (Myrup and Ranzieri 1976). 

Estimation of the Monin-Obukhov Length Estimate L for an agricultural area with windspeed at 10m equal to 2.5ms 1 and solar flux 500 Wm 2. 

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