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El Niño
Coriolis Effect
• Earth rotates from west to east
• The Coriolis Effect is the influence of
Earth’s rotation on air, or on any object
moving on Earth’s surface.
• Objects in motion seem to be moving in a
curve when they are actually moving in a
straight line.
•http://www.youtube.com/wat
ch?v=_36MiCUS1ro
El Niño
• El Niño was first recorded in 1525 by
Peruvian fishermen who noticed that the
Peru current warmed up every few
years. Since it often happened around
Christmas, the current was called El
Niño (The Christ child).
A Normal Year: Peru
• Normally the trade winds blow from east to
west, pushing warm surface water into the
Western Pacific and increasing the water
level by 1.5 cm.
• A cold water upwelling, full of nutrients,
comes up to replace the warm surface
water off the Peru/Chile coast.
El Niño Year
• Every few years the trade winds slacken
or even reverse (we are not sure why).
• The warm water that was piling up in the
western Pacific begins to move east.
• 150 m of warm water flows across the
Pacific and buries the upwelling by the
Peru/Chile coast.
El Niño and Weather
• El Niño is considered to be the largest
single weather influence on Earth.
• It changes the path of the jet stream,
and thus affects weather everywhere.
• Normally, the jet stream is a single
‘ribbon’ of air high over North America
• During an El Niño, the jet stream splits in
two, one part heading into Canada and the
other section moving south into the US.
• As a result, California gets severe
weather, and the southern US gets
massive rainstorms.
• The Atlantic coast, including the Maritimes
tends to get warmer winters and summers
because the jet stream cuts off a lot of bad
weather before it can migrate north.
Severe El Niños
• 1982-83: killed
2000 people
and caused
about 13
billion dollars
in damage
worldwide
• 1997-98: killed 2100 people and caused
33 billion dollars in damage. It gave us the
hottest summer on record. It was also the
first one to be predicted.
Predicting El Niños
• Since 1994 there have been 70
stationary buoys in the equatorial
Pacific which monitor water
temperature from the surface to 500
meters deep, wind direction, air
temperature and relative humidity.
• Also, since 1992 a US/French satellite relays
data about surface water elevation and ocean
circulation.
• Computers analyze the transmitted data
• This is how the 1997-98 El Niño was predicted
La Niña
• When El Niño
reverses the weather
patterns don’t always
go back to normal;
sometimes they
overcompensate
giving us colder than
normal conditions –
when this happens it
is called La Niña.