TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Geography > Atmospheric Circulation
The circulation cells and surface winds help distribute energy over the Earth.
The Hadley Cell is thermally driven by the rising hot air at the equator, creating low pressure. The warm air travels 30'N and 30'S where it cools and then sinks.
The Ferrel Cell is thermally indirect. It is driven by the falling air at 30'N and 30'S and by the rising hot air at 60'N and 60'S.
The Polar Cell is thermally driven, and is found at 60'N and 60'S. As the cold air moves towards the Equator, it meets the warmer air which causes it to rise.
Rossby waves and jet streams influence the air movement.
Rossby Waves are large scale belts of undulating winds which occur at latitudes of 10000 - 12000m.
Within these waves are very fast moving winds called jet streams. There are 2 in each hemisphere.
