El+Niño

=**Normal Conditions**= In a normal global condition, the trade winds blow from east to west, crossing the tropical Pacific. Due to the upwelling of cold water, the ocean water is warmer in the west and colder in the east; along with a cooler climate temperature near South America. The difference in water temperature these areas have affects the weather the regions undergo. The air cools, in the east, due to the temperature of the water; therefore, making the air too dense to create clouds and rain (Peru). In the west, on the other hand, the air is heated, due to the warmer temperature of water, increasing the chances of rain (Indonesia).

=**The Causes of El Ni****ño**= In an El Nino, the trade winds weaken, relaxing around the western central part of the Pacific (in some cases the winds not only weaken but they reverse in direction.) This means that the warm water that was supposed to move towards the west side stays in the east, resulting in warmer water in the east and colder water in the west, creating the phenomenon called El Nino. The warm ocean waters form clouds and rain hitting the regions that normally wouldn’t receive precipitation and drought in those who should normally receive precipitation. The atmosphere produces high and low pressure patterns, in response to El Nino. Having a pattern of high and low pressures affect the earth more than we can imagine, which will be explained below.



=**The Growth of El Ni****ñ****o**= Since the temperature of sea water affects the force of the winds, the warmer the ocean, the weaker the winds become. Due to the winds force decreasing, the warm water in the eastern area doesn’t move towards the west. This means that the eastern sea waters remains warm, causing the winds to become weaker; and the cycle continues. This is what geographers refer to as positive feedback; and it is responsible for the growth of El Nino and prolonging it.

=**Effects of El Niño**=

El Nino phenomenon occurs in the Pacific Ocean and is the result of constant interaction of clouds, storms, winds, oceanic temperatures, and ocean currents. Since the climate can be changed by many components, El Nino is a major cause for the variability in climate throughout the globe. El Nino causes a disruption in the seasonal cycle and these changes are most often seen during the wintertime. El Nino uses teleconnections, which are “large scale changes in the circulation of the atmosphere that allow atmospheric circulations from one region to affect the climate from another region,” (Anderson & Strahler, 2008) to create these climate changes in the tropical regions.  The western winds that flow during the phenomenon cause an ocean surface temperature to be 8 degrees Celsius higher in the west pacific and cause a sea surface uprising of about ½ a meter. Locations that normally see rainy weather are exposed to dryer temperatures and vice versa. There is normally warm temperature near the equatorial region during El Nino. There is heavy rain in the south of the U.S and Peru, while drought in west Pacific Ocean. For example in the winter of 1997-1998, there were extreme climate changes. While there was heavy rain in Peru, Ecuador, Florida, California, and Kenya, there was drought in Australia, Mexico and Central America. During El Nino, in the coast of Peru the winters are wet and there is cool temperature in South America. Fish populations increase and other marine ecosystems flourish significantly because the water is full of nutrients. It takes a couple of seasons or years for the seasonal cycle to get back on track. Once this happens the tropical ocean cools and the east to west sea surface gradients are restored.



References:

1. Anderson, B. T., & Strahler, A. (2008). // Visualizing weather and climate //. (p. 361). Hobokan, New Jersey: John Wiley & Sons. 2. // Global consequences of el niño //. (n.d.). Retrieved from http://www.pmel.noaa.gov/tao/elnino/impacts.html 3. // Indonesia prepares for el nino effect as regional drought continues //. (2009, August 03). Retrieved from http://www.zimbio.com/pictures/cKKxSwYTPZV/Indonesia Prepares El Nino Effect Regional 4. Netting, R. (2003, January 22). // El nino - and what is the southern oscillation anyway?! // . Retrieved from http://kids.earth.nasa.gov/archive/nino/intro.html 5. Peirce, D. W. (1997, June 25). // So what is an el niño, anyway? a non-technical description //. Retrieved from http://meteora.ucsd.edu/~pierce/elnino/whatis.html 6. Reynolds, R., Dettinger, M., Stephens, D., Cayan, D., Highland, L., & Wilson, R. (2003, November 25). // Effects of el niño on streamflow, lake level, and landslide potential //. Retrieved from http://geochange.er.usgs.gov/sw/changes/natural/elnino/ 7. "What Are ENSO Impacts?" International Research Institute for Climate and Society, 27 Mar. 2008. Retrieved from []. 8. W// hat is an el niño? // . (n.d.). 16 March.2012. Retrieved from http://www.pmel.noaa.gov/tao/elnino/el-nino-story.html 9. Welch, C. (n.d.). // Earthlyissues //. Retrieved from http://www.earthlyissues.com/ninilanina.htm

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