1. 1. Functions and composition of the atmposphere.

Definition: atmosphere is the gaseous layer that surrounds the Earth.

Composition. It is made up of water vapour and mixture of gases:
nitrogen, 78%
oxygen, 21%
ozone.
carbon dioxide.

Functions.

Its makes life on Earth possible because:

1. it provides gases that are essentials to life (oxygen).
2. it filters dangerous solar radiation
3. it regulates the planet's temperature.
4. it protects the planet from the impact of meteorites.

The atmosphere's layers.
We can divide the atmosphere into five layers with different characteristics

1. Exosphere between 500 and 10.000 kilometres.
2. Ionosphere, between 500 and 80 kilometres. Its high temperature (1500 deegres) causes meteorites to disintegrate.
3. Mesosphere, between 80 and 50 kilometres. The coolest layer of the atmosphere (-90 deegres).
4. Stratosphere, between 50 and 12 kilometres. It contains the ozone layer that protects Earth from ultraviolet rays
5. Troposphere, between 12 kilometres and Earth's surface. It produces the planet's meteorological and climatic phenomena.