- the rate of decrease of atmospheric temperature with increase of elevation vertically above a given location.
- the rate of change of any meteorological factor with altitude, esp atmospheric temperature, which usually decreases at a rate of 0.6°C per 100 metres (environmental lapse rate). Unsaturated air loses about 1°C per 100 m (dry adiabatic lapse rate), whereas saturated air loses an average 0.5°C per 100 m (saturated adiabatic lapse rate)
