El Niño (Encyclopedia of Science)
El Niño (pronounced el-NEEN-yo) is the name given to a change in the flow of water currents in the Pacific Ocean near the equator. El Niñopanish for "the child" because it often occurs around Christmasepeats every three to five years. Although El Niño takes place in a small portion of the Pacific, it can affect the weather in large parts of Asia, Africa, Indonesia, and North and South America. Scientists have only recently become aware of the far-reaching effects of this phenomenon.
What is El Niño?
The rotation of Earth and the exchange of heat between the atmosphere and the oceans create wind and ocean currents. At the equator, trade winds blow westward over the Pacific, pushing surface water away from South America toward Australia and Indonesia. These strong trade winds, laden with moisture, bring life-giving monsoons to eastern Asia. As warm surface water moves west, cold, nutrient-rich water from deep in the ocean rises to replace it. Along the coast of Peru, this pattern creates a rich fishing ground.
Every three to five years, however, the trade winds slacken, or even reverse direction, allowing winds from the west to push warm surface water eastward toward South America. This change is called the Southern Oscillation (oscillation means swinging or swaying), and it is brought about by a shifting pattern of air pressure between the...
(The entire section is 1086 words.)
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