EL NINO

The El Niño phenomenon is an abnormal weather pattern caused by the warming of the Pacific Ocean. It is characterized by extreme climatic changes - world-warming along South America, torrential rains in North America, extreme temperature rise and drought in Southeast Asia and Australia. El Niño occurs every two to seven years.

El Niño is Spanish for "the boy" and refers to the Christ child, because periodic warming in the Pacific near South America is usually noticed around Christmas. "La Niña," on the other hand, is Spanish for "the girl." El Nino is also known as the southern oscillation.

El Niño phenomena dramatically affects the weather throughout the world. Among other weather anomalies, El Niño events are responsible for:

•       A shift of thunderstorm activity eastward from Indonesia to the south Pacific, which leads to abnormally dry conditions and severe droughts during both warm and cold seasons in Australia, the Philippines, Indonesia, southeastern Africa and Brazil.
•       During the summer season the Indian monsoon is less intensive than normal and therefore it is much less rainy than usual in India.
•       Much wetter conditions at the west coast of tropical South America.
•       El Niño impacts on the United States, North America and the Atlantic regions include:
•       Wetter than the normal conditions in tropical latitudes of North America, from Texas to Florida, including more intensive wintertime storms.
•       Extreme rainfall and flooding events in California, Oregon and Washington.
•       Much milder winters and late autumns in northwestern Canada and Alaska due to pumping of abnormally warm air by mid-latitude low pressure systems.
•       Below normal hurricane/tropical cyclone activity in the Atlantic (however, their strength is not limited by El Niño).
•     Drier than normal North American monsoons, especially for Mexico, Arizona and New Mexico.
•       Drier than normal autumns and winters in the U.S. Pacific Northwest.

What Causes El Niño?

The warming of the Pacific occurs as a result of the weakening of trade winds that normally blow westward from South America toward Asia.

Global Wind Patterns: wind belts of the general circulation

The global wind pattern is also known as the "general circulation," and the surface winds of each hemisphere are divided into three wind belts:

Polar Easterlies: From 60-90 degrees latitude.

Prevailing Westerlies: From 30-60 degrees latitude (aka Westerlies).

Tropical Easterlies: From 0-30 degrees latitude (aka Trade Winds).