The rate of decrease in temperature with increase in altitude of an air parcel which is expanding slowly to a lower atmospheric pressure without exchange of heat; for a descending parcel it is the rate of increase in temperature with decrease in altitude. Theory predicts that for dry air it is equal to the @[email protected] of gravity divided by the specific heat of dry air at constant pressure (approximately \(9.8\ ^{\unicode{x26ac}} \text{C}\ \text{km}^{-1}\)). The moist @[email protected] lapse rate is less than the dry @[email protected] lapse rate and depends on the moisture content of the air mass.
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2171 [Terms] [Paper]