Lecture 23- El Nino Flashcards
how often does El Nino occur?
every 3-7 years
how long does El Nino last?
8 months
What did Sir Gilbert Walker notice?
- correlation between Darwin Australia and Tahiti
- when one had high sea level pressure (dry air that weighs a lot), the other had low sea level pressure
what is responsible for the correlation between two weather stations?
east-west component of the tropical Hadley Cell
winds at the ocean surface (trade winds)
- rush TOWARD the equator
- Coriolis force turns the winds to the right to blow EAST TO WEST
winds aloft
- rush AWAY from the equator
- Coriolis force turns the winds to the right to blow WEST TO EAST
What did Sir Gilbert Walker notice about the east-west atmospheric circulation?
periodically reverses direction
El Nino Conditions
- warm water on the right
- low pressure at Tahiti
- weak or reverses trade winds
- little or no equatorial upwelling
La Nina conditions
- exceptionally strong trade winds
- equatorial upwelling and cooling in the Eastern Pacific
What should happen to global-average temperature when the thick warm pool of water in the western Pacific spreads out across a large area of the equatorial Pacific during an El Nino period?
temperature will GO UP
El Nino’s direct impact on Pacific precipitation and storm patterns
- drought conditions in Australia/Indonesia
- Pacific hurricanes increase but Atlantic hurricanes decrease
El Nino’s effect on equatorial productivity
low equatorial productivity
How does El Nino influence weather patterns around the globe?
jet streams
El Nino —, La Nina —
El Nino warms, La Nina cools
