The El Nino is a natural climate cycle that occurs every three to seven years. It is characterized by the warming of waters in the Pacific Ocean near the equator. This warming can have far-reaching impacts on global weather patterns, including increased rainfall in some areas and drought conditions in others. The name “El Nino” comes from Spanish for “the little boy” or “Christ child”, as this phenomenon was traditionally associated with the Christmas season.
El Nino events typically occur every three to seven years, but there is considerable variability in both the timing and intensity of these events. The most recent El Nino occurred from 2014-2016 and was one of the strongest on record, with widespread impacts felt around the globe. While El Nino conditions are often associated with increased rainfall, they can also lead to drought conditions in other parts of the world. For example, the 2015-2016 El Nino event resulted in severe drought conditions across Indonesia and Australia.
There are a number of factors that contribute to the formation of an El Nino event. One of the most important is the Walker Circulation, which is a large-scale wind pattern over the tropical Pacific Ocean. The Walker Circulation consists of two cells: an upper-level cell that blows surface winds from east to west (towards Indonesia), and a lower-level cell that returns deeper water back towards South America via ocean currents. During an El Nino event, this circulation weakens or even reverses direction, resulting in warmer than normal water temperatures across much of the eastern and central Pacific Ocean.
While not all scientists agree on exactly how or why this happens, it is thought that changes in atmospheric pressure over Indonesia (known as the Indonesian Throughflow) play a role in disrupting the Walker Circulation during an El Niño event . When this happens, warm water that would normally be kept east of Indonesia by prevailing winds begins to flow westward towards South America . This pooling of warm water along South America’s coast results in higher than average sea surface temperatures (SSTs) across much of this region . These warmer than normal SSTs are what we typically think of when we refer to an “El Niño event” . In addition to impacting global weather patterns , El Niño events also tend to suppress Atlantic hurricane activity while increasing tornado activity across North America