Adiabatic Lapse Rate Calculator

About this calculator

As an air parcel rises it expands and cools because atmospheric pressure drops with altitude — the rate of that cooling is the adiabatic lapse rate. Dry, unsaturated air cools at the dry adiabatic lapse rate (DALR) of about 9.8°C per kilometer; once the parcel is saturated and water vapor condenses, the released latent heat slows the cooling to the moist adiabatic lapse rate (MALR), typically 4–9°C per kilometer depending on temperature and moisture content. This calculator applies the appropriate rate to your surface temperature and altitude gain to find the parcel's new temperature.

Meteorologists use lapse rates to judge atmospheric stability and forecast whether rising air will keep building into thunderstorms, pilots use the same physics to estimate density altitude and cloud base height, and mountaineers and hikers use it as a rule of thumb to predict how much colder it will be at altitude.