How Does El Nino and La Nina Affect Weather Patterns? Essay

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El Nino is the single largest cause of variability in the world’s climate change every 3 to 4 years and may last for 12 to 18 months. It means male child in Spanish and it refers to a weak warm current appearing around Christmas along the coast of Ecuador and Peru. It disrupts the normal Pacific Ocean circulation and is described as a warm event. On the other hand, La Nina is an opposite event, a cold event, from El Nino and it means female child in Spanish. It refers to the appearance of colder than average sea surface temperatures in the central and East Equatorial Pacific. It may follow El Nino but it has occurred less frequently. They are both short term climatic changes and are amongst the most powerful phenomena on earth as they affect the climate over almost half of the earth. During a normal year, there is high air pressure off the coast of South America with descending air. In the western Pacific, there is low air pressure as warn, moist air rises, cools and condenses, forming rain clouds which give heavy convectional rainfall. This movement of air results from the Walker cell. This circulation of air is where air in the upper atmosphere moves from west to east and surface air moves from east to west, as the trade winds. It causes surface waters in the west to be pushed upwards therefore sea levels in places such as the Philippines is 60cm higher than in Panama or Colombia. Water flowing westwards is warm, 28ºC in the western Pacific whereas the water off the coast of South America is cold, 20ºC. This results in an upwelling of nutrient rich water along the Peruvian coast heading to optimum fishing conditions because of the abundance of phytoplankton. The El Nino Sothern Oscillation (ENSO) is the term used by scientists to describe the combined oceanic, El Nino, and atmospheric, Southern Oscillation, impacts of phenomenon which leads to a disruption of

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