User:Nathan Johnson/Beta drift

Beta drift refers to the southwestward motion in the Southern Hemisphere and the northwestward motion in the Northern Hemisphere of a tropical cyclone caused by the variation in the Coriolis parameter. Also referred to as beta gyres or the beta effect. The drift results in a propagation speed of about 1–2 meters per second (3.6–7.2 kilometers per hour, 2.2–4.4 miles per hour, 2–4 knots).

For a mesoscale system like a tropical cyclone, there is a significant difference between the value of the Coriolis parameter at the northern edge and the southern edge. As a result of the circulation of winds around the storm, the relative vorticity is changed because the absolute vorticity is advected around the storm.