Stratosphere

The stratosphere ( [ ʃtratosfɛ ː rə ] or [ stratosfɛ ː rə ]; stratum of Latin, "ceiling" and Greek σφαῖρα sphaira, " ball ") is the second layer of the earth's atmosphere, it is above the troposphere. The boundary between the stratosphere and troposphere is called the tropopause. This is at a height of about 8 kilometers to the geographic poles and about 18 km at the equator. About the stratosphere, the mesosphere follows, the limit is the stratopause at about 50 km altitude. The main difference between the troposphere and stratosphere is the cause of the temperature curve. In the troposphere, the air circulation with its adiabatic properties determines the temperature profile in the layers above resigns the importance of convection and the radiative equilibrium is determinative. According to the results of the radiative transfer equation, the outer layer of each gas shell ( Sun, Venus, Earth, Mars ) a stratosphere in a broader sense, which can be divided into further stories in the strict sense. This condominium building atmospheres recognized already in 1906 Karl Schwarzschild.

In the stratosphere, the temperature in the medium decreases with increasing altitude slowly, but which may occur locally by heating from above to a temperature rise. In the Erdstratosphäre this increase is from about 20 km significantly - this inverse temperature gradient is caused mainly by the left in the stratosphere, ozone absorbs UV radiation from sunlight and thereby converts electromagnetic radiation into heat. The strongest is the heating in the ozone layer, where the temperature rises from -60 ° C up to just below 0 ° C to. This area is the stratosphere in the strict sense, about the temperature decreases with height again. But never again an adiabatic temperature drop is achieved.

Due to the low temperature at the tropopause condensed atmospheric water vapor there almost completely, for this reason, the stratospheric air is very dry. Clouds form in the stratosphere usually only under the extremely cold conditions of the polar night.

In the stratosphere can be observed also limited weather phenomena. It is part of homosphere. The stratosphere was - as well as the tropopause - discovered in 1902 by the French meteorologist Léon- Philippe Teisserenc de Bort and the German Richard Assmann. Today, it is with research aircraft such as the Mjassischtschew M -55 " Geophysika " or the " ER- 2" special version of the Lockheed U-2 was investigated. Since end of July 2010 also flies stationed in Oberpfaffenhofen HALO, a development based on the Gulfstream G550, scientific flights.

2010, the Cranfield Astro Biological Stratospheric Sampling Experiment ( CASS -E) was launched, which collected with a balloon probe samples from the stratosphere, which are then investigated for possibly existing extraterrestrial microorganisms.