# Moist-adiabatic lapse rate

From AMS Glossary

(Redirected from Saturation-adiabatic lapse rate)

## moist-adiabatic lapse rate

(

*Or*saturation-adiabatic lapse rate.) The rate of decrease of temperature with height along a moist adiabat.It is given approximately by Γ where

_{m}in the following:*g*is gravitational acceleration,*c*_{pd}is the specific heat at constant pressure of dry air,*r*_{v}is the mixing ratio of water vapor,*L*_{v}is the latent heat of vaporization,*R*is the gas constant for dry air, ε is the ratio of the gas constants for dry air and water vapor, and*T*is temperature. This expression is an approximation to both the reversible moist adiabatic lapse rate and the pseudoadiabatic lapse rate, with more accurate expressions given under those definitions. When most of the condensed water is frozen, this may be replaced by a similar expression but with*L*_{v}replaced by the latent heat of sublimation.