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El Nino Southern Oscillation (ENSO) - Coggle Diagram
El Nino Southern Oscillation
(ENSO)
What is it?
weather phenomenon that
occurs at irregular intervals
between 2 + 10 years
Begins...
when warm water in Western
tropical Pacific Ocean
Shifts
EASTWARDS
along
the equator to coast of S.America
why
? CHANGE IN DIRECTION
OF TRADE WINDS
Normal Conditions
Trade winds blow
EAST TO WEST
warm water pushed to = Australian coast
(western pacific)
cold water = S.America coast
(eastern pacific)
Australia = warm water heats air above it ∴ rising air
LOW PRESSURE
cools to dew point temp
wet weather
S. America = upwelling of colder water from deeper levels in E.Pacific
(Humboldt Current)
HIGH PRESSURE
subsiding air
dry, colder weather
DIAGRAM
El Nino Conditions
Trade winds
WEAKEN
(due to
change in atmospheric pressure)
& blow WEST to EAST
warm water
pushed to =
S.American coast
(east pacific)
weaker upwelling
of cold water = Australian coast
(west pacific)
Australia now experiences
HIGH PRESSURE
subsiding air
dry weather conditions
DROUGHTS + FIRES
eg.1982-83 - Australia
forest fires
71 dead, 8000 homeless
& $3bn damage
S.America now experiences
LOW PRESSURE
rising air
wet weather
HEAVY RAINFALL + FLOODING
eg. 1982-83 - Ecuador + Peru
lots of rain + flooding
600 dead + 650m damage
NOT just LOCAL EFFECTS -
Global winds + weather patterns
affected too
TELECONNECTIONS
eg. 1982-83
South Africa - drought - $1bn damage
S.India - drought - 50+ dead
La Nina
(opposite of El Nino)
Exaggerated normal
conditions
Trade winds blow more
strongly from EAST to WEST
**VERY STRONG UPWELLING
of cold water**
warm water = Australian coast
cold water = S.American coast
Australia - rapid rising air + strong
low pressure
normal wetter weather now...
INTENSE RAINFALL + SERIOUS FLOODING
S.America - very cold water
causes strong high pressure
normal dry weather
VERY DRY + VERY HOT