El Nino Phenomenon

El Niño and La Niña Phenomena
El Niño and La Niña are the names given to changes in the winds, atmospheric pressure, and seawater that occur in the Pacific Ocean near the equator. El Niño and La Niña are opposite phases of a back and forth cycle in the Pacific Ocean and the atmosphere above it. Unlike winter and summer, however, El Niño and La Niña do not change with the regularity of the seasons; instead, they repeat on average about every three or four years. They are the extremes in a vast repeating cycle called the Southern Oscillation, El Niño being the warm extreme and La Niña the cold extreme.
Although El Niño and La Niña take place in a small portion of the Pacific, the changes caused by Southern Oscillation 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 the Southern Oscillation on the world's weather. An El Niño during 1982–83 was associated with record snowfall in parts of the Rocky Mountains, flooding in the southern United States, and heavy rain storms in southern California, which brought about floods and mud slides.
The name El Niño comes from Peruvian fishermen. They noticed that near the end of each year, the seawater off the South American coast became warmer, which made fishing much poorer. Because the change appeared each year close to Christmas, the fishermen dubbed it El Niño, Spanish for "the boy child" referring to the Christ child. Every few years, the changes brought with El Niño were particularly strong or long lasting. During these strong El Niños, the warmer sea waters nearly wiped out fishing and brought significant
changes in weather. For example, normally dry areas on shore could receive abundant rain, turning deserts into lush grasslands for as long as these strong El Niños lasted. In the 1950s and 60s it was found that strong El Niños were associated with increased sea surface temperatures throughout the...