The Earth's atmosphere plays a crucial role in shaping the weather, climate and life-supporting systems. However, the ocean and atmosphere are the earth's fluid outer layers and are closely connected. Before focussing upon the ocean and its processes, it would be appropriate to examine the atmosphere and the processes that control its movements. In fact most human beings spend their lives at the base of the huge mass of air that forms the outer layers of our planet.
Air is a mixture of gases.
The various gases which surround the earth are bound to it by the gravitational force of attraction. Like the Earth's ecological and biological systems, the atmosphere has evolved over time, changing in properties and composition. The Earth's, atmosphere was created from the inside. It is believed that dissolved gases escaped from the earth's interior as the planet cooled and the crust solidified. The gravitational pull of the planet trapped the gases close to the earth.