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El Nino and La Nina
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What weather phenomena has the largest impact on weather in the western US ?
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El Niño and La Niña
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Definitions: La Niña - Unusually cold surface water temperatures in the Pacific ocean caused by strong easterly trade winds.
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El Niño - Unusually warm surface water temperatures in the Pacific ocean caused by weak (or reversed direction) easterly trade winds.
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El Niño and La Niña simplified…
El Nino is the abnormal heating of Earth’s ocean surface in the Pacific. La Nina is the abnormal cooling of Earth’s ocean surface in the Pacific.
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Did You Know… El Nino means “The Christ Child”
They were discovered hundreds of years ago They can be caused by underwater volcanoes La Nina means “Little Girl” They occur half as often as El Nino’s
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Time Pattern El Nino usually lasts from a year to two years.
The longest El Nino ever recorded lasted six years. La Nina usually lasts nine to twelve months. The longest ever recorded lasted three years. El Nino La Nina. Oracle Think Quest. Retrieved May 14th,
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Causes: El Nino is caused when trade winds allow warm water from the Pacific to flow east. This builds up warm surface water that will soon cause the El Nino. La Nina is caused when the temperatures drop in the pacific, also being blown east. This builds up at the coasts and will cause a La Nina.
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What causes an El Niño? Weak trade winds and weak upwelling cause warm water off the coast of S. America
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What causes a La Niña? Strong trade winds blow surface water towards east, creating colder surface temperatures off South American coast. We get strong upwelling.
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What causes the patterns?
Normal
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Movement of Ocean Water
Surface currents Deep ocean currents Upwelling
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Surface Ocean Currents
Currents that are controlled by the wind. ~¼ mile depth, 10%
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Currents controlled by water density: temperature and salinity
Deep Ocean Currents Currents controlled by water density: temperature and salinity 90% of the ocean water moves in deep ocean currents
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Upwelling upwelling brings up cold, nutrient-rich waters to the surface, which encourage seaweed growth and support blooms of phytoplankton.
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Upwelling This happens along the coast, and when this happens it creates animal diversity. Phytoplankton use these nutrients to grow and reproduce at rapid rates. This attracts organisms to areas of upwelling that rely on phytoplankton as food and, in turn, attracts their consumers. This areas is rich in biological activity and diversity. Approximately half of the fish caught in the world come from areas of upwelling.
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El Nino’s Damage Done Floods in the Pacific states
Cause tornadoes in the mid-west states Causes severe thunderstorms in the south Northeast typically has stormy winters, "Snowmageddon”
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La Nina’s Damage Done Drier and Milder conditions in the south.
Cause severe droughts in the southeast. Cause unusual cold temperature changes along the Pacific coast. Causes wetter conditions for the Pacific states. Northeast will have cold periods
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Strange phenomenon occur during an El Niño and La Niña like...
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Brush fires caused by drought in Texas (La Niña)
From the decline of anchovy populations to the increase of drought and tropical storms. All of these phenomenon have been linked to El Niño and La Niña events.
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Increased Tropical Storms (La Niña)
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Hurricane Floyd was HUGE! (1999 - La Niña)
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Causing devastating floods in Australia (2010-2011 La Niña)
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Peruvian anchovy populations declined (El Niño)
Cooler, nutrient rich waters associated with El Niño drop along with the thermocline, driving the anchovy population down with it, or killing off a large portion.
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Star Tribune Aug 2 1993 Minneapolis, MN FLOODS Upper Mississippi Basin
Source: Trenberth
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More tornadoes through tornado alley?
NO!!! Scientists have found no significant correlation between El Niño and La Niña weather patterns and increased tornadoes.
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The drought of 1988: cost about $40 billion
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Watch Videos (3 minutes each)
Science Cheat Sheet National Geographic Video La Nina water movement explained
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QUIZ! Which is which… Normal, El Niño, La Niña?
B C
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Were you’re predictions correct?
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Videos : If time El Nino explanation video 3min La Nina explanation video 3.5min Austin newscast in January talking about Australia flooding 2min Texas weatherman predictions for this year from July about 3min All three animations
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