Horizontal and vertical circulation system of ocean waters, produced by gravity, wind friction, and water density variation. Coriolis forces cause ocean currents to move clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere and deflect them about 45° from the wind direction. This movement creates distinctive currents called gyres. Major ocean currents include the Gulf Stream-North Atlantic-Norway Current in the Atlantic Ocean, the Peru (Humboldt) Current off South America, and the West Australia Current
A movement of ocean water characterized by regularity, either of a cylic nature, or more commonly as a continuous stream flowing along a definable path Three general classes, by cause may be distinguished: ( a) currents related to sea water density gradients, comprising the various types of gradient current ; ( b) wind-driven currents , which are those directly produced by the stress exerted by the wind upon the ocean surface; ( c) currents produced by long-wave motions The latter are principally tidal currents , but may include currents associated with internal waves , tsunamis , and seiches The major ocean currents are of continuous, stream-flow character, and are of first-order importance in the maintenance of the earth's thermodynamic balance