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Ocean currents

{alt}An animation of ocean currents{more}Click 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 cross-section through the Atlantic Ocean, showing surface and deepwater currents. Red arrows are warm currents, blue arrows...Read More >>A cross-section through the Atlantic Ocean, showing surface and deepwater currents. Red arrows are warm currents, blue arrows cold 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 Scotland. The Gulf Stream brings with it a mild climate to northwestern parts of...Read More >>Palm trees growing on the northwest coast of Scotland. The Gulf Stream brings with it a mild climate to northwestern parts of Europe.

Warm and cold

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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