Adiabatic lapse rate

The rate at which air temperature decreases with altitude as an air parcel rises and expands (or increases as it descends and compresses) without exchanging heat with surrounding air. The dry adiabatic rate is approximately 3°C per 1,000 feet; the saturated adiabatic rate varies but averages about 2°C per 1,000 feet due to latent heat release from condensation.