Transcript What do we already know?

Water (Ocean) and
Air (Atmosphere)
Interactions
Source:
http://esminfo.prenhall.com/science/geoanimations/animations/26_NinoNina.html
Animation
Trade Winds
Ocean Currents
Air Pressure
Air and water
temperature
What do we already know?
•Density: Warm vs. cold? What rises? What sinks?
•Pressure:
High temperature = ?
low temperature = ?
High pressure = what type of weather? Why?
Low pressure = what type of weather? Why?
Wind = ?
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
low temperature means high air pressure.
High pressure = fair weather. Air masses press
down, Warm air cannot rise so no clouds form.
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- video
Western
Pacific
(Australia)
Eastern
Pacific
(Peru)
Guide questions:
1. In what direction would the wind blow?
2. Describe the climate in the Western Pacific? What about the Eastern Pacific?
Consider:
a. pressure systems (high or low)
b. ocean/air temperature
Western
Pacific
(Australia)
Eastern
Pacific
(Peru)
Trade winds
blowing
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?
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)?
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
La Nina
Funny El Nino Definition
But really…
literally means “the little boy”
refers to baby Jesus Christ because El Ninos
start around Christmas time
Western
Pacific
(Australia
)
Eastern
Pacific
(Peru)
Trade winds
blowing
Normal Conditions
results from weakening easterly trade
winds
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/eln/home.rxml
• Trade winds
weaken
Trade winds normally go from South America (High
Pressure) towards Australia (Low pressure) and keep
warm water closer to Australia
When Trade winds weaken (don’t know why), warm water
can spread closer to South America
Impact of El Nino in
the News
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)
Start of El Nino
End result of El Nino
El Niño causes all sorts of unusual weather, sometimes bringing rain to coastal
deserts of South America which never see rain during non-El Niño years. The
flooding results in swarming mosquitoes and the spread of disease.
During El Nino
Years
1) Water near Peru is warm
2) No cold water comes up (upwelling) to
bring nutrients
3) No nutrients = decrease fish population
 Bad year for fishing
During La Nina
Years
1)More cold water comes to surface (upwelling) and
brings many nutrients
2)Fish populations get very large
Good year for fishing
Facts about El Nino and La
Nina
• Currently in La Nina year! (2011)
• Last El Nino was last year (2010)
– Occur every 2-7 years
• La Ninas do not always happen after El
Nino’s
– Only about half the time
SOURCES:
•http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/eln/home.rxml
•PAGASA-DOST