Editing Tropopause (section)

==Definition==
[[Image:Earth Atmosphere.svg|thumb|'''The atmosphere of planet Earth:''' The ''tropopause'' is between the troposphere and the stratosphere.]]
Rising from the planetary surface of the Earth, the tropopause is the atmospheric level where the air ceases to become cool with increased altitude and becomes dry, devoid of water vapor. The tropopause is the boundary that demarcates the [[troposphere]] below from the [[stratosphere]] above, and is part of the atmosphere where there occurs an abrupt change in the [[lapse rate|environmental lapse rate]] (ELR) of temperature, from a positive rate (of decrease) in the troposphere to a negative rate in the stratosphere. The tropopause is defined as the lowest level at which the lapse rate decreases to 2°C/km or less, provided that the average lapse-rate, between that level and all other higher levels within 2.0 km does not exceed 2°C/km.<ref>{{cite book|title= International Meteorological Vocabulary|edition= 2nd|date= 1992|publisher= Secretariat of the World Meteorological Organization|location= Geneva|isbn= 978-92-63-02182-3|page= 636}}</ref> The tropopause is a [[Continuous function|first-order discontinuity]] surface, in which temperature as a function of height varies continuously through the atmosphere, while the [[temperature gradient]] has a discontinuity.<ref>{{Cite book |last=Panchev |first=S. |title=Dynamic Meteorology |date=1985 |publisher=D. Reidel Publishing Company |isbn=978-90-277-1744-3 |series=Environmental fluid mechanics |location=Dordrecht, Boston, Lancaster |language=en}}</ref>