0Atmosphere is the layer of gases surrounding earth. The air is an important component of earth mass and 99% of the total mass of the atmosphere is concentrated at a height of 32 kilometers above the earth surface .
Atmosphere composition
Earth atmosphere comprises about
78% - nitrogen
21% - oxygen
.03%- carbon dioxide
.9%- argon
.1%- other gases ( neon , water vapour, methane and others)
Water vapour and carbon dioxide are found up to 90 km from the earth’s surface .
Atmosphere structure
Atmosphere is divided into 5 layers, depending on temperature and density
1) Troposphere - it is the lowest layer and its average height is 12 km and extends roughly to a height os 8 km near the poles and about 18 km at the equator.
Approximately 75-80% of the mass 9f entire atmosphere is contained in the atmosphere.
Temperature in the Troposphere decrease with altitude.
Tropopause - The zone separating the Troposphere from the stratosphere.
2) Stratosphere- The stratosphere rises to a height of 50 km , above the tropopause
It contains the Ozone layer which absorbs ultraviolet radiation and shields life on the earth from intense , harmful forms of energy .
Temperature increases with altitude . There is almost no water vapour .
3) Mesosphere- It is located between 50-80 km above the surface of earth.
Temperature decreases with altitude.
4) Thermosphere- It is located between 80-700 km above earth surface .
The ionosphere ( between 80-400 km ) is a part of it . It contains ions, which are charged particles
Temperature increases with height .
It is clouds and water vapour free .
The international space station ( ISS ) situated in the Thermosphere.
5) Exosphere - It is the topmost layer of earth’s atmosphere is known as the exosphere.
Located between 700-10000 km above the earth surface . Because the molecules in this layer have a very low density, this layer doesn't behave like gases and allows particles to escape into space .
