Editing Lapse rate (section)

{{Short description|Vertical rate of change of temperature in atmosphere}}
[[File:Tatra Rysy 5.jpg|thumb|Higher [[Czarny Staw pod Rysami]] lake (elevation {{convert|1,583|m|ft|0}}) is still frozen as the lower [[Morskie Oko]] lake has already almost melted (elevation {{convert|1,395|m|ft|0}}). Photo from [[Poland|Polish]] side of the [[Tatra mountains]], May 2019.]]

The '''lapse rate''' is the rate at which an atmospheric variable, normally [[temperature]] in [[Earth's atmosphere]], falls with [[altitude]].<ref>{{cite book |first=Mark Zachary |last=Jacobson |title=Fundamentals of Atmospheric Modeling |publisher=[[Cambridge University Press]] |edition=2nd |year=2005 |isbn=978-0-521-83970-9}}</ref><ref>{{cite book |first=C. Donald |last=Ahrens |title=Meteorology Today |publisher=Brooks/Cole Publishing |edition=8th |year=2006 |isbn=978-0-495-01162-0}}</ref> ''Lapse rate'' arises from the word ''lapse'' (in its "becoming less" sense, not its "interruption" sense).  In dry air, the '''adiabatic lapse rate''' (i.e., decrease in temperature of a parcel of air that rises in the atmosphere without exchanging energy with surrounding air) is 9.8 °C/km (5.4 °F per 1,000 ft). The saturated adiabatic lapse rate (SALR), or moist adiabatic lapse rate (MALR), is the decrease in temperature of a parcel of water-saturated air that rises in the atmosphere. It varies with the temperature and pressure of the parcel and is often in the range 3.6 to {{nobr|9.2 °C/km}} (2 to {{nobr|5 °F/1000 ft}}), as obtained from the [[International Civil Aviation Organization]] (ICAO). The '''environmental lapse rate''' is the decrease in temperature of air with altitude for a specific time and place (see below). It can be highly variable between circumstances.

Lapse rate corresponds to the vertical component of the [[spatial gradient]] of [[temperature gradient|temperature]]. Although this concept is most often applied to the Earth's [[troposphere]], it can be extended to any gravitationally supported [[fluid parcel|parcel of gas]].