Do Now;

• Are there weather patterns that influence places thousands of miles away?

Aim: What is El Nino?

Pic: Normal Conditions vs. El Nino

What is El Nino?

• A climate variation that takes place in the tropical Pacific once every 3-7 years

• Lasts for about 1 year

Normal Weather Conditions in the Pacific

• Trade winds move warm surface waters of Pacific away from the west coast of Central & South America

• Cold ocean water that lies under the displaced water moves to the surface– Causes thermocline to rise– Brings nutrients– Keeps water cool– More fish in the area

El Nino Weather Conditions:Southern Oscillation

• Reversal of high & low pressure regions on either side of the Pacific

• Trade winds are weakened or reversed• Upwelling slows/stops off the coast of Central &

South America so less nutrients

No Upwelling= Big Concerns

• Environmental Impact: – Without upwelling, there are less nutrients resulting

in a decline in fish populations• Economic impact: – Fisheries are hit hard– Devastating effect on countries that use fishing as a

main source of income like Peru

Pic: Normal Conditions vs. El Nino

Effects of El Nino …Cont’d

• The northern US & Canada experience warmer winters & less intense hurricane season

• The eastern US & regions of Peru & Ecuador (typically dry) have higher-than-average rainfall

• The Philippines, Indonesia, & Australia are drier than normal resulting in devastating brush fires

La Nina

• Reverse of El Nino• Surface waters of the ocean surrounding

Central & South America are colder than normal