La Nina ~ Climate issue research

When i started i didn't know much about the topic but it sounded interesting then after research i found that la Nina is defined as cooler than normal sea-surface temperatures in the central and eastern tropical Pacific ocean that impact global weather patterns.(1) La Nina comes every few years and can stay for up to two years but is usually only normal for La Nina to stay for 9-12 months. It is an extreme phases of a naturally occurring climate cycle. (1) La nina is caused by a buildup of un normally cold subsurface waters in the tropical Pacific. At higher latitudes, El Niño and La Niña are among a number of factors that influence climate.(2) La Niña means "The Little Girl." La Niña is sometimes called El Viejo (Old Man), anti-El Niño, or simply "a cold event" or "a cold episode".(3) La nina is mostly over Indonesia and northern Australia and brings higher than normal pressure over the eastern tropical Pacific. More wet conditions are know to be over Africa and northern Brazil, during the northern winter season. Also there are drier than normal condition during the cold episodes.(4) La Nina is thought to occur because of very strong trade winds that as pressure rises in the east, there is typically an accompanying decrease in the west. The studies of La nina and el nino also led to the realization that Asian monsoon seasons under certain barometric conditions were often linked to drought in Australia, Indonesia, India and parts of Africa, and to mild winters in western Canada.
As a rule, the effects of La Niña are more direct and dramatic during the Northern Hemisphere winter. La Niñas may affect weather patterns in certain parts of the world, causing abnormally high rainfall in southeast Asia and dry conditions in the desert areas of South America. Some impacts of previous La Niñas include:

∑ Abnormally heavy monsoons on the Indian subcontinent.
∑ * In the United States, colder and snowier winter in the northern states west of the Great Lakes. Drier than normal winter in the Southeast. Warmer and drier winters in the Southwest. Enhanced hurricane activity around the mid-Atlantic states.
* Torrential rains leading to floods in Southeast Asia.
* Wet weather in eastern Australia.
* Cool and wet winter in southeastern Africa
(5)




All images from :
http://images.google.com/images?gbv=2&hl=en&q=Global+effects+of+La+nina&btnG=Search+Images





(1)
http://www.elnino.noaa.gov/lanina_new_faq.html

(2)
http://www.pmel.noaa.gov/tao/elnino/la-nina-story.html

(3)
http://www.publicaffairs.noaa.gov/lanina.html

(4)
http://www.cpc.noaa.gov/products/analysis_monitoring/lanina/cold_impacts.shtml

(5)
http://www.msc-smc.ec.gc.ca/education/lanina/global/index_e.cfm