La Nina and El Nino

Phenomena

http://edition.cnn.com/video/#/video/weather/2009/07/27/byrnes.ctw.aregentino.el.nino.cnn?iref=videosearch Impact

http://www.youtube.com/watch?v=AEoHz56jWGYEl Nino Definition

Water (Ocean) and Air (Atmosphere) Interactions

Trade Winds

Ocean Currents Air Pressure

Air and water temperature

Source: http://esminfo.prenhall.com/science/geoanimations/animations/26_NinoNina.htmlAnimation

La Nina 2011 videohttp://www.youtube.com/watch?v=iWTucpsClLc&NR=1&feature=fvwp

What do we already know?•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.

NORMAL CONDITIONS

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)

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)

Eastern Pacific(Peru)

Trade winds blowing

LA Nina CONDITIONS

Western Pacific

(Australia)

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)?

Trade winds blowing

Western Pacific

(Australia)

Eastern Pacific(Peru)

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

• Trade winds weaken

Global Impact

La Nina

http://www.youtube.com/watch?v=ovDp1crqdOUEl 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.

      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

Atmospheric Consequences of El Niño

influencing weather patterns worldwide

Why do we care: Global climate impacts continued

FloodsLakeport, California (1998)

FiresAustralia (1998)

SOURCES:

•http://esminfo.prenhall.com/science/geoanimations/animations/26_NinoNina.html

•http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/eln/home.rxml

•PAGASA-DOST