06 What is the stratosphere?
Description
This article is from the Ozone Depletion FAQ, by Robert Parson rparson@spot.colorado.edu with numerous contributions by others.
06 What is the stratosphere?
The stratosphere extends from about 15 km to 50 km. In the
stratosphere temperature _increases_ with altitude, due to the
absorption of UV light by oxygen and ozone. This creates a global
"inversion layer" which impedes vertical motion into and within
the stratosphere - since warmer air lies above colder air, convection
is inhibited. The word "stratosphere" is related to the word
"stratification" or layering.
The stratosphere is often compared to the "troposphere", which is
the atmosphere below about 15 km. The boundary - called the
"tropopause" - between these regions is quite sharp, but its
precise location varies between ~9 and ~18 km, depending upon
latitude and season. The prefix "tropo" refers to change: the
troposphere is the part of the atmosphere in which weather occurs.
This results in rapid mixing of tropospheric air.
[Wayne] [Wallace and Hobbs]
Above the stratosphere lie the "mesosphere", ranging from ~50 to
~100 km, in which temperature decreases with altitude; the
"thermosphere", ~100-400 km, in which temperature increases
with altitude again, and the "exosphere", beyond ~400 km, which
fades into the background of interplanetary space. In the upper
mesosphere and thermosphere electrons and ions are abundant, so
these regions are also referred to as the "ionosphere". In technical
literature the term "lower atmosphere" is synonymous with the
troposphere, "middle atmosphere" refers to the stratosphere
and mesosphere, while "upper atmosphere" is usually reserved for the
thermosphere and exosphere. This usage is not universal, however,
and one occasionally sees the term "upper atmosphere" used to
describe everything above the troposphere (for example, in NASA's
Upper Atmosphere Research Satellite, UARS.)
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