February 28, 2011
Weather Patterns - El Nino and La Nina
The clouds in the sky, the temperature of the ocean waters, the temperature of the Earth itself, the El Nino and La Nina cycle and the sunlight all play a major role in weather patterns. Whenever there is a major change such as floods in areas that are usually dry, winters that are extraordinarily wet or cold and summers that are unusually warmer or cooler than normal, we are seeing the effects of El Nino and La Nina. These two weather patterns together form what is known as the El Nino Southern Oscillation (ENSO) phenomenon.
Every five years or so the tropical area of the Pacific Ocean experiences the El Nino and La Nina weather patterns. When the eastern tropics of the Pacific start warming at least 0.5ºC (0.9ºF) or cools the same amount lasting anywhere from nine months to two years, the ENSO patterns emerge. This effect will "play" with the weather all around the world from New Zealand to England, from America to China. Not a single area of Earth will be unaffected.
What happens here?
In the United States the National Oceanic Atmospheric Administration (NOAA) has been doing research since the 1980's on the ENSO phenomenon. The Southern Oscillation is the atmospheric portion of the pattern, while El Nino is the oceanic and Earthbound portion. When convection and cloud formation take place, the heat exchange from the atmosphere to the Earth's surface goes into a flux.How it works
Rainfall and cloud cover shift as the ocean warms over the eastern and central equatorial regions of the Pacific rather than the standard equatorial Indian and west Pacific regions. During a La Nina event, the opposite will take place.While on paper this looks to be mildly different, the results in real life can be devastating. Flooding occurs in areas like the Midwestern United States, the Western United States, Asia, Australia and several other areas of the world when ENSO has its teeth bared. Kind of gives a whole new meaning to the song lyrics "row, row, row your boat.." doesn't it? Row, row, row your home gently down the stream... nope, just doesn't seem "merry" at all. Areas in these parts of the planet have experienced floods where dry land has always been.
The winter of 2011 is one of the worst on record in several parts of the United States, the United Kingdom and other countries like Australia and New Zealand. A new term, thundersnow, was introduced on the East Coast in the U.S.; Britain, Scotland and Ireland had days where they warned people to stay inside unless it was necessary to leave and just as New Zealand and Australia were coming off a period of record flooding, cyclones hit with devastating force. This is all due to ENSO. The earthquake of 2011 had nothing to do with it, though.
The specific things that occur with La Nina are varying. The tropics in the Pacific will be cooler just below the surface and from the east wind and waves come in to bring that coldness to the surface. This can move the jet stream from its normal position to further north or south. It is a combination of all of these things that causes the extreme weather and NOAA is researching to be able to predict these instances.
Weather can impact our daily lives in ways that we cannot see, much less understand fully. The way that the wind blows and where it blows; where the clouds are forming; the temperatures planetwide; and the exchange back and forth from sea to air will dictate our weather patterns. Where and how we live and where and what we eat are hooked up in a never ending natural waltz as the planet dances with its counterpart above to form the weather we see and the land on which we live.