The circulation of air in the atmosphere is caused by the rotation of the Earth and energy from the Sun as warm air rises and the colder air sinks. Large scale air movement in the atmosphere is called atmospheric circulation.
Atmospheric circulation also distributes heat on the surface of the Earth. The wind belts and jet streams that girdle the Earth are directed by three convection cells that transport heat from the equator to the poles.
The three cells that direct air movement are the Hadley cell, Ferrel cell and the Polar cell. The Ferrel cell produces westerly winds. The Hadley cell is closest to the equator and produces northeast trade winds. The polar cell circulates cold air towards the equator.