The atmosphere
Radiation propagation in the atmosphere

The atmosphere can be considered as a series of layers concentric with the earth, delimiting several zones.

The two main zones are :

• the homosphere, located from the ground to an altitude of about 80 to 90 km ;

• the heterosphere, beyond.

Within the homosphere, three main atmospheric layers are defined, differentiated by their temperature gradient with altitude (figure 3):

• the troposphere ;

• the stratosphere;

• the mesosphere.

The troposphere is the lowest atmospheric layer, characterized by a regular temperature decrease with altitude,...