What is El Nino? ~ El Nino Facts & FAQ

by Bob

in Weather

What is El Nino?
El Nino is an abnormal warming of surface ocean waters in the eastern tropical Pacific. While this may sound pleasant for swimmers it can have profound effects on weather patterns around the world. El Ninos tend to happen every 3-7 years.

El Nino Definition-
Literally means the little boy in Spanish which is a reference to the Christ child. Fishermen in South America noticed that the fishing ground to a halt every 3-7 years and usually occurred  around Christmas and thus named it El Nino.

What are the effects of El Nino?
Effects vary considerably from one El Nino to the next but can include:
  • Effects show up most clearly during wintertime
  • Linked with drought not just in parts of Latin America but in southeastern Africa, South Asia, Indonesia and Australia.
  • El Niño usually brings a warm winter to the northern USA from the Pacific Northwest across to the Midwest and sometimes the Northeast
  • Reduction in the number of hurricanes that form over the Atlantic Ocean, especially strong ones
El Nino

Notice the warmer water in the lower picture indicated by the red? That’s El Nino

Which El Nino was the strongest this century?
The 1982/83 El Nino is estimated to have caused more than US$10 billion in weather-related damage worldwide.

What are El Nino weather patterns?

  • Cooler and wetter weather to the southern United States
  • Warmer weather to western Canada and southern Alaska
  • Drier weather to the Pacific Northwest
  • Cooler weather to northern Canada
  • Wetter weather to southern California

What are some benefits of El Nino?

  • Hurricanes in the Atlantic are believed to be suppressed, and semi-arid areas welcome “flooding” that irrigates crops and replenishes water reservoirs.
  • Warmer temperatures in North America

What is the difference between El Nino and La Nina?
El Nino refers to a pattern characterized by the tropical Pacific’s warmest water spreading eastward to the coast of South America. La Niña refers to times when waters of the tropical Pacific are colder than normal.

How does El Nino affect sea life and birds?
El Niño cuts off the upwelling of cold water from lower-levels of the ocean off the Pacific Coast of South America. This upwelling, colder water brings many of the nutrients that keep the food chain going. When this happens, the fish either die or migrate north or south into areas where they’ll find more to eat. With the fish gone, the sea birds that depend on them either die or go elsewhere.

What is ENSO?
It is the “El Nino-Southern Oscillation,” the name scientists use for what is often called El Niño. Historically, El Niño referred to warming of ocean water in the eastern Pacific. The Southern Oscillation is a see-saw shift in surface air pressure between Darwin, Australia, and Tahiti. When pressure is high at Darwin, it’s low at Tahiti and vice versa. In the 1950s scientists realized that the El Niño and the Southern Oscillation were parts of the same event. During normal times, the pressure is lower at Darwin than at Tahiti. But during the warm phase, usually called “El Niño,” the pressure is lower at Tahiti.

What causes El Nino?
Every 3-7 years for some  not well-understood reason, trade winds in eastern Asia weaken. This weakening causes warm water to pile up and through natural currents this warmer water migrates towards South America.

What happens to the ocean also affects the atmosphere. Tropical thunderstorms are fueled by hot, humid air over the oceans. The hotter the air, the stronger and bigger the thunderstorms. As the Pacific’s warmest water spreads eastward, the biggest thunderstorms move with it. If you look on a map, you will see that suddenly islands like Tahiti, normally tropical paradises, experience massive storms.

Currently, it is not well understood what initiates these changes, and it is likely that it is a large combination of things. The current thinking is that it has to do with oscillations such as the Madden-Julian Oscillation in the tropical Pacific, Atmospheric Angular Momentum, and frictional and mountain torque.

El Nino can have impacts on weather at various locations around the globe. Off the east coast of southern Africa, drought conditions often occur. In countries such as Zimbabwe, the effects of drought can be devastating.

The clouds and rainstorms associated with warm ocean waters also shift toward the east. Thus, rains which normally would fall over the tropical rain forests of Indonesia start falling over the deserts of Peru, causing forest fires and drought in the western Pacific and flooding in South America. Moreover the Earth’s atmosphere responds to the heating of El-Nino by producing patterns of high and low pressure which can have a profound impact on weather far away from the equatorial Pacific. For instance, higher temperatures in western Canada and the upper plains of the United States, colder temperatures in the southern United States. Enhanced precipitation, particularly in the winter occurs from coastal California through the southern United States and across much of the East Coast.

When will be the next El Nino?
The odds are quite high that El Nino will make a return this year (2015). Australia’s Bureau of Meteorology states that all 7 of its climate models indicate the return of El Nino. Their models indicate a continued warming of the Pacific Ocean in the coming months with EL Nino conditions expected during the late summer or early fall.

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