El Nino and La Nina
I would like to know the difference between El Nino and La
what would the world weather patterns be like if El Nino and La Nina
were not present. Also, what is Upwelling? Does it have something to
do with warm water combining with cold water? Thank you.
El Nino is the condition when the atmosphere and ocean
currents cause a movement of warmer water to the eastern
Pacific. There is kind of a snowball effect when the process
begins that can result in severe warming of the ocean
off the northern west coast of South America. This prevents
water from deeper in the ocean from upwelling to the surface.
Nutrients and food for fish do not get to the upper layer of
ocean for food fish to eat. This causes
fish to migrate further south, disrupting the South
American fishing industry and causing severe drought in western
South America. This also, usually, causes drought in the
southwestern part and plains of North America.
La Nina is the opposite condition, when warm water builds up
in the western Pacific Ocean, often causing drought conditions
there and leaving northern South America with floods and northern
North America with mild, wet summers and drought in the southeastern
In between El Nino and La Nina are "normal" conditions. So, if the
El Nino and LA Nina did not occur, we would have less variable
weather conditions. This would be better for agriculture and
the fishing industry, at least.
Argonne National Laboratory
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Update: June 2012