Atmosphere
systems
The Earth's mass exerts a gravitational force
that holds to the Earth a large
amount of gases, known as the atmosphere.
Life on Earth requires a particular
atmospheric composition, and this composition is in turn maintained by the interaction between
biological
systems and the atmospheric system
The atmosphere consists of five layers:
1. the troposphere,
2. the stratosphere,
3. the mesosphere,
4. the thermosphere, and
5. the exosphere.
The thickness of these layers is slightly different around the globe, and also varies according to temperature and season.