An atmosphere is a layer of gas that surrounds a planet.

The Earth's atmosphere is divided by scientists into  5  theoretical layers:

  • The Troposphere contains 80% of the 5 trillion tons of air! In direct contact with and heated by the ground, this layer of air is where the important thermal exchanges responsible for meteorological  phenomena take place.
  • In the Stratosphere, the temperature gets higher as altitude increases. This temperature inversion acts as a limit for clouds. It is here that we fiind the Ozone Layer that filters out a large part of the ultraviolet radiation coming from the Sun.
  • In the Mesosphere, the temperature once again begins to drop.
  • Those rare particles still present in the Thermosphere interact with solar radiation. In absorbing this energy, they increase in temperature and ionize. This is the ionosphere. This part of the Thermosphere has important electromagnetic properties.  The International Space Station (ISS) is in orbit in the thermosphere, beyond the ionosphere.
  • Particles are so rare in the Exosphere that the probability of collisions among them is negligible. Some even escape the gravitational attraction of the Earth. Although the boundary is not clearly defined, the exosphere marks the beginning of outer space. The majority of satellites are orbiting in the exosphere, at altitudes between 800 km and 36,000 km.