Description: The circulation in the atmosphere is composed of three circulation cells in the northern and southern hemispheres. These cells are caused by the rotation of the Earth which creates the Coriolis force. The Coriolis force deflects northern hemisphere motion to the right and southern hemisphere motion to the left. The majority of large-scale motion in the atmosphere is in geostrophic balance, meaning the Coriolis force acting on the motion is balanced by a pressure gradient force. The rotation of cyclones and anticyclones in the northern and southern hemispheres is controlled by this geostrophic balance.