The rate at which air temperature decreases with altitude. The environmental lapse rate averages about 6.5°C per 1,000 metres.
measurementWhat is Lapse Rate?
The environmental lapse rate (ELR) is the observed rate of temperature decrease with altitude in the free atmosphere. It averages 6.5°C/km but varies with moisture content, season and location. The dry adiabatic lapse rate (9.8°C/km for unsaturated air) and wet adiabatic lapse rate (~5°C/km for saturated air) are theoretical rates for rising air parcels. When the ELR exceeds the adiabatic lapse rate, the atmosphere is unstable and convection (thunderstorms) is favoured.
Key points
- The rate at which air temperature decreases with altitude. The environmental lapse rate averages about 6.5°C per 1,000 metres.
- Category: measurement
Related terms
See also: lapse-rate is connected to other weather concepts. Browse the full glossary for related definitions.