An essay on the causes of drought in Australia

Australia experiences considerable variation in its rainfall. If we could take a ` typic ten-year tipwe would crease over about four years of high uper up amountrainfall, one-third f convey(a) years and three infra median(a) years. These fluctuations in rainfall haveseveral amazes, legion(predicate) of which be not fully understood. Probably the main grounds of major rainfallfluctuations in Australia is the southerlyOscillation, which is a major transmission landmark public press shiftbetween the Asiatic and east Pacific regions. Thestrength and commission of the Southern Oscillationis measured by a simple tycoon called the SouthernOscillation Index (SOI). The SOI is calculatedfrom the monthly or seasonal fluctuations in sortpressure loss between Tahiti and Darwin. When there ar `typical pressure patternsprevailing, the SOI is close to zero. If the SOIbecomes strongly positive this means that thesea-level air pressure at Darwin is some(prenominal) lowerthan n ormal and a La Niña showcase occurs. LaNiña is a period of well above average rainfall ineasterly Australia, which often brings floods. southerly OSCILLATIONDuring an El Niño event, the SOI is stronglynegative and the sea-level air pressure atDarwin is higher than at Tahiti. An average yearoccurs when the SOI is between 10 and +10. ALa Niña event occurs when the SOI is above +10;an El Niño event occurs when it is on a lower floor 10. Probably the main cause of drought in eastern Australiais El Niño Ð a fond sea current in thePacific. At irregular intervals, it spreads furthersouth and the peeing in the central and easternPacific becomes much warmer, legal transfer heavy rainfalland floods to arid parts of South America. At the very(prenominal) time, normally warm water in theoceans to the east and northern of Australia arereplaced by much ice chest water as the warm waterspreads east. As well, the easterly disdain windsthat normally coulomb crosswise the Pacific O ceanbringing warm, moist air to Australia s! hocktheir direction. There is an accompanying reversalof air pressure across the Pacific, resulting instrong high pressure systems building up overWeather conditions in (a) a typical year, and (b) an El Niño year frigidness deep waterEl NiñoTypicalOcean Cold upwellingceases. Warm surface currents reverse. AustraliaAustraliaTrade winds reverse direction.

AtmosphereAtmosphereSouthAmericaSouthAmericaOceanWarm surface waterStrong surface currentsUpwelling of colddeep waterTrade winds blow towards Australia. Warm come up aircauses thunderstormsand floods. change sinking aircauses droughts. dry out sinking air causesd roughts. Warm rising air causesthunderstorms andfloods. close of Australia. The result isstable and drier air dominatingAustralia with below averagerainfall and often severedroughts. El Niño brings signifi-cant climatic change, not only toAustralia except to other parts ofthe world. In late(a) years scientists havemade great advances in understandingand forecasting ElNiño and Southern Oscillationevents. The National ClimateCentre in Australia offers outlookson rainfall three monthsahead. These outlooks are proving to be of greatvalue to farmers and especially valuable for ecologicallysustainable discipline in rural areas. hypertext transfer protocol://library.thinkquest.org/C003603/english/droughts/causesofdroughts.shtmlhttp://www.vasat.org/learning_resources/drought/html/m1l3/resources/coping_with_drought/1660.html If you want to get a full essay, ordinance it on our website: OrderCustomPaper.com

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