The Saturated Adiabatic Lapse Rate (SALR) is the rate at which the temperature of a parcel of air saturated with water vapour changes as the parcel ascends or descends.
The SALR is often taken as 1.
Problems arise when, on ascent, the dew point of the air is reached, and the rate of cooling is therefore less - it follows the SALR figure.
If there is sufficient moisture, then this mositure will condense and the air will then cool at the saturated adiabatic lapse rate (SALR) which is less than the DALR.
When the air is saturated with water vapour (reached its dew point), the moist adiabatic lapse rate (MALR) or saturated adiabatic lapse rate (SALR) applies. It varies with temperature and pressure, but is usually near 4.9 °C/km (2.7 °F/1000 ft).
Instability caused by dry air advecting over warm and humid PBL air. Lapse rate of temperature increases if lifting occurs since the low level air cools at the SALR while the mid-level air cools at the DALR.
See also: Cloud, Air, Water, Surface, Temperature