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Ocean currents

An animation of ocean currentsAn animation of ocean currentsClick to play video The ocean waters move about the globe in great “rivers” called ocean currents. Surface currents have a big effect on the world’s climates. They make polar regions milder and the tropics cooler. Surface currents are driven by the winds and move in roughly circular patterns, called gyres. These go round in a clockwise direction in the Northern Hemisphere and anticlockwise in the Southern Hemisphere. 

A map of the world's ocean currents A map of the world's ocean currents

Surface and deepwater currentsSurface and deepwater currents

Deepwater currents

There are two kinds of ocean currents: surface currents, which are swept along by the wind, and deepwater currents, which are driven by differences in density (the colder and saltier the water is, the greater its density).  

Palm trees growing on the northwest coast of ScotlandPalm trees growing on the northwest coast of Scotland

Warm and cold

Warmed by the Sun, surface waters flow in currents from the tropics towards the poles, while cold currents move in to take their place. In the Atlantic Ocean, there is a warm current flowing northeast from the Gulf of Mexico as far as the coast of Norway in northern Europe. Called the Gulf Stream, it brings mild, wet weather to northwestern Europe.

Every few years, ocean currents in the Pacific Ocean change about. Warm water moves eastwards towards South America. Called El Niño (“The Child”), it cuts off the food supply for the local fish, and causes droughts and storms.

Friendly FloateesFriendly Floatees

Friendly Floatees

El Niño is Spanish for "the child" and refers to the infant Jesus, because the occasional warming in the Pacific Ocean off South America occurs around Christmas.

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