The mesosphere is delimited:
- towards the earth through the stratopause (at about 50 km altitude) from the stratosphere
- up through the mesopause (at an altitude of 80 to 90 km) from the thermosphere .
The mesosphere extends from about 50 km to 85 km in height.
In the mesosphere, the temperature drops from around 0 ° C at the stratopause with seasonal fluctuations to an average of around −90 ° C at an altitude of around 80 kilometers, due to the extremely thin air and the fact that there is hardly any ozone left and the Absorption of the high-energy UV radiation only takes place in the underlying stratosphere. The temperature decrease in the mesosphere is, however, at around 3 K / km, considerably less than in the troposphere . Since the mesosphere is located above the ozone layer , the UV light here is still so strong that a human body would incur severe burns within a very short time. The mesopause, during which the temperature remains constant, lies above the mesosphere . It rises strongly again in the thermosphere, depending on solar activity up to 2,000 ° C.
In the mesosphere there is a circulation from the summer to the winter pole, which causes an upward transport of air masses in the area of the summer pole and a downward transport in the area of the winter pole. Due to the associated adiabatic cooling of the air (in the area of the summer pole) or warming (in the area of the winter pole), the mesosphere is significantly colder (by around 130 to 150 K) in summer (i.e. in the area of the summer pole) than in winter.
The chemical composition of the mesosphere, like that of the troposphere and the stratosphere, is fairly constant: its main components are nitrogen , oxygen , argon and carbon dioxide . The mesosphere is part of the homosphere .
Luminous night clouds
Luminous night clouds form in the upper mesosphere of the polar ice caps in summer . These can be seen with a bluish-silver shimmer with the naked eye even in moderate latitudes when they reflect the light of the setting sun. It is probably an accumulation of ice particles that should not be confused with the northern or northern lights and also not with the polar stratospheric clouds .
- Radar observations of meteors in the mesosphere / lower thermosphere over Juliusruh in November 1999 ( Memento from September 28, 2007 in the Internet Archive )