El
Nino

http://www.youtube.com/watch?v=AEoHz56jWGY
El Nino Definition http://edition.cnn.com/video/#/video/weather/2009/07/27/byrnes.ctw.aregenti
no.el.nino.cnn?iref=videosearch Impact

Air
Source: http://esminfo.prenhall.com/science/geoanimations/animations/26_NinoNina.html
Animation
Trade Winds
La Nina 2011 video http://www.youtube.com/ watch?v=iWTucpsClLc&NR=
1&feature=fvwp
Ocean Currents Air Pressure
Air and water temperature

•Density : Warm air is less dense than cool air. Warm air rises. Cool air sinks. (convection)
•Pressure :
 High temperature means low air pressure and low temperature means high air pressure .
 High pressure = fair weather . Air masses press down,
Warm air cannot rise and form clouds.
Low pressure = cloudy, rainy weather . Air masses move apart, warm air rises and form clouds.
 Air moves from an area of high to low pressure.

Western
Pacific
(Australia)
Eastern
Pacific
(Peru)
Guide questions:
1. In what direction would the wind blow?
2. Describe the climate in the Western Pacific? Eastern Pacific? Consider a. pressure systems (high or low) b. ocean temperature

Western
Pacific
(Australia)
Trade winds blowing
Eastern
Pacific
(Peru)
Guide questions:
1. Describe what is happening in the atmosphere (Walker Circulation Cell)?
2. Why is rain most likely to happen over a longer period in the Western Pacific?

Western
Pacific
(Australia)
Trade winds blowing
Eastern
Pacific
(Peru)
Guide questions:
1. What would happen to the water in the Eastern Pacific if the trade winds got stronger?
2. What would be the result of cold water moving towards the West (Think about the weather)?

Western
Pacific
(Australia)
Guide questions:
1. Why is there heavier rain observed in more countries in the western Pacific?
2. What changes in weather would occur in North America? Hint: red circle
Eastern
Pacific
(Peru)

• Trade winds weaken

http://www.youtube.com/watch?v=ovDp1crqdOU
El Nino/La Nina video (with impact on fishing and US weather)

During non-El Niño years, the southeast trade winds , drag surface water westward away from shore. As surface water moves away, upwelling brings up colder waters from depths of 40-80 meters or more. This deep sea water is rich in nutrients which can sustain large fish populations.

During an El Niño event , the southeast trade winds weaken and so does the amount upwelling in the eastern Pacific.
The deeper thermocline means that any upwelling that does occur is unable to tap into the rich nutrients found in deeper waters. Consequently, warm nutrient-poor water predominates the region and a decrease in the fish population is observed.

Atmospheric Consequences of El Niño influencing weather patterns worldwide
Drought in Southern Africa, Southern India, Sri Lanka, Philippines,
Indonesia, Australia, Southern Peru, Western Bolivia, Mexico, Central
America
Heavy rain and flooding in Bolivia, Ecuador, Northern Peru, Cuba, U.S.
Gulf States
Hurricanes in Tahiti, Hawaii

Why do we care: Global climate impacts continued
Floods
Lakeport, California (1998)
Fires
Australia (1998)

SOURCES:
• http://esminfo.prenhall.com/science/geoanimations/animations/2
6_NinoNina.html
• http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/eln/home.rxml
•PAGASA-DOST