El nino powerpoint
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Transcript of El nino powerpoint
El Ninomass of warm surface water moving west to
east across equatorial Pacific Ocean
part of larger phenomenon called El Nino – Southern Oscillation (ENSO)
• winds move from areas of highpressure to areas of low pressure
ex: air from balloon exits balloon
normal situation over Pacific Ocean(non-El Nino year):
• low pressure over Asia• high pressure over South America• winds blow east to west• shallow thermocline along South
America, lots of upwelling, cold waterat surface
• deeper thermocline near Asia, warmsurface water piles up
El Nino years over Pacific Ocean:
• pressure change = Southern Oscillation• higher pressure over Asia• lower pressure over South America• winds weaken or blow west to east• thermocline deepens along South
America, little upwelling, warmer water at surface• warm surface water sloshes back along
equatorial Pacific
sea surface temperature in Pacific Ocean
• El Nino occurs every 3 to 8 years• usually lasts about 1 year• scientists do not know why pressure
changes causing winds to shift• warm water arrives at South America
around Christmas – hence El Nino – for the Christ Child
Effects of El Nino
• upwelling along Peru reduced• warm water with few nutrients rises• fisheries decline
Effects of El Nino• increased precipitation over parts of
South America, western andsouthern U.S.
• can result in severe flooding• drought in Australia, Indonesia,
Phillipenes• reduction in annual monsoons in India• can result in severe crop damage• severe property damage and thousands
of deaths
La Nina• opposite El Nino• swings the other way and winds blow
more than normal towards west