Adiabatic Lapse Rate

The rate at which air temperature changes as an air parcel rises or descends without exchanging heat with its surroundings. The dry adiabatic lapse rate is approximately 3 degrees Celsius (5.4 degrees Fahrenheit) per 1,000 feet, which applies to unsaturated air. Once the air cools to its dew point and condensation begins, the moist (saturated) adiabatic lapse rate takes over at roughly 2 degrees Celsius per 1,000 feet, because the latent heat released by condensation partially offsets the cooling. Comparing the environmental lapse rate to these values determines atmospheric stability.