Atmosphere Contents

1. Structure And Composition

The atmosphere is the layer of air which blankets the Earth; it is made up of a number of gases

The Atmosphere

The atmosphere is essential for the existence of life and interacts with the other main components of the global ecosystem. The Earth initially had an atmosphere with little oxygen and larger concentrations of gases such as methane. It changed over hundreds of millions of years, it is believed, as a result of the release of oxygen by the earliest life forms. This is an example of the complex interactions between the different components of the global ecosystem. The atmosphere is now the main source of oxygen and carbon dioxide for terrestrial life and an essential part of the hydrological cycle. It protects animals from harmful radiation and, through the greenhouse effect, retains some of the sun's heat to create a surface temperature conducive to life.

What is the atmosphere?