The dry adiabatic rate, or dry adiabatic lapse rate, refers to the rate at which temperature changes as 5.5 degrees Fahrenheit per 1,000 feet. When a parcel of air is lifted, the air temperature decreases as pressure lowers at increasing height.
The lapse rate is a dry adiabatic rate as long as the air remains unsaturated at less than 100 percent relative humidity. However, when there is this much humidity, the rate at which the temperature changes decreases to 3 degrees Fahrenheit per 1,000 feet. This occurrence is known as the moist adiabatic lapse rate. The average adiabatic rate is approximately 3.3 degrees Fahrenheit.