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Yannay Kaplan-
El Niño, La Niño- September 23rd, 2012
El Niño Description
Have you ever heard the words El Niño and/or La Niño and had no idea what they
meant? El Niño is the warming of the Pacific Ocean off the western coast of South America
that usually occurs every 4 to 7 years between the months of December to January. During El
Niño the Pacific trade winds don’t push the warm Pacific Ocean water from the west coast of
South America as far west as usual across the Pacific. This affects the weather patterns
between the tropics of Cancer and Capricorn. The meaning of El Niño in Spanish is “The
Child or the Boy” so named because it occurs around Christmas when Jesus was born.
La Niña Description
During La Niña the trade winds strengthen and push the warm Pacific Ocean water
farther west than usual as shown in illustration 1. La Niña also affects the weather patterns
between the tropics of Cancer and Capricorn. La Niña means “The Girl”
[Illustration 1: The trade wind movements of La Niño]
El Niño’s and La Niña’s whereabouts and movements:
During both El Niño and La Niña the warm current travels along the coast of South
America and turns west along the equator to Indonesia, down Australia and back east to
South America. This can take between 12-18 months.
Effects of El Niño and La Niña
El Niño’s Effects on Weather:
During El Niño the ocean water becomes warmer which produces more rainfall on
South America and more storms in the sea. This happens because the water is warmer so
more of it evaporates into the air, and the more water in the air, the more rainfall and storms
there are in that area. The effects of El Niño on South America are shown below in Illustration
2. As a result of El Niño the Southern half and the West coast of South America both
experience floods and most of the Northern half experiences drought [see Illustration 2].
Illustration 3 shows the effect of El Niño around the world in the months of June-August. The
color red means there’s drought in that area and the color blue means that there are floods in
that area. Australia, most of Indonesia, some parts of Asia, Africa and a little part of Europe
and North America all suffer drought because of El Niño. The south of South America, the
east of Indonesia, a little bit of North America (the dead middle), Europe and the North of
Africa all suffer from floods because of El Niño.
Illustration 2: The effects of El Niño on South America
Illustration 3: Worldwide effects of La Niña
El Niño Effect on Sea-Life:
The warm Pacific water remains off South Americas west coast and because of that,
the cool, nutrient rich water can’t come up from below it. This means that fish don’t have the
food they need to survive and not many are attracted to that area. As a result, fishing is
decreased. For example, in the 1997-1998 El Niño the amount of fish caught decreased from
14 million tonnes in the previous year to 3.5 million tonnes [see illustration 2]
La Niña Effects on Weather
During La Niña, the trade winds push the warm Pacific water farther than usual west
across the Pacific Ocean letting the cold nutrient-rich water come up to the surface and cover
more area. This makes the eastern side of the Pacific Ocean drier and colder than it is usually
because there isn’t enough warm water that evaporates into the air to make the rain. La
Niña’s effects are shown in illustration 4. The effects of La Niña are dry near the Southwest of
South America, the mid-west is quite cool, and the north of South America is wet and cool. La
Niña’s cooler temperatures also affect Canada from British Columbia’s west coast, through
the Prairie Provinces, and into Ontario. Southern B.C. also gets more snow than average
when a La Niña occurs. As shown in illustration 4, South America, Africa, the Pacific Islands,
Indonesia and America are all places that are affected by La Niña.
Illustration 4: The worldwide effects of La Niña
La Niña Effects on Sea Life
Because the warm Pacific water goes farther west than usual, the cool, nutrient rich
water below it can come up to the surface and cover more area than usual, allowing for a
richer supply of fish in the Eastern Pacific Ocean. As a result, fishing is boosted. Fishing is
boosted from Peru to Canada. Sockeye salmon will travel through the Strait of Juan de Fuca
because of the lower temperatures which allows the American fishing vessels to share the
catch.
The main difference between El Niño and La Niña is the weather. In most places, the
weather is the opposite when El Niño occurs to when La Niña occurs.1
The Ongoing Occurrence of La Niña and El Niño
While many people can simply shrug and shovel some extra snow, others must adapt
their livelihood to catching fewer fish, planting crops at different times, or simply going hungry
for a year while El Niño and La Niño occur.
Bibliography
http://www.knmi.nl/research/global_climate/enso/effects/
1
http://www.pmel.noaa.gov/tao/elnino/gif/winter.gif
http://biophysics.sbg.ac.at/atmo/el-scans/el-nino1.jpg
http://www.pmel.noaa.gov/tao/elnino/gif/summer.gif
http://earthobservatory.nasa.gov/Features/ElNino/
http://www.answers.com/topic/el-ni-o
http://www.stormsurf.com/page2/tutorials/enso.shtml
http://weather.about.com/od/oceanweatherinteractions/a/La_Nina.htm
http://www.environmentalgraffiti.com/meteorology/news-three-effects-cyclical-la-niñ-weather-pattern