Transcript The Atmosphere

The Wind
 Result of uneven heating of the
Earth’s surface
Image courtesy
of NASA.
– causes differences
in air pressure
to develop (cold air
near the poles,
warm air near the
Equator)
– Molecules always move from areas of
high pressure to areas of low pressure
Image courtesy of
Weather Informer.
Sea Breeze…
 Caused by uneven heating of land & water (Land
heats/cools FASTER than water)
 Happens during the day
 Warmer air over land rises/cooler air over ocean
sinks
 WIND BLOWS from high pressure (SEA) to the
low pressure (LAND)
Image courtesy of University of Hawai’i
Kaptolani Community College.
Land Breeze…
 Caused by uneven heating of land & water (Land
heats/cools FASTER than water)
 Happens at night
 Warmer air over ocean rises/cooler air over land
sinks
 WIND BLOWS from high pressure (LAND) to the
low pressure (SEA)
GLOBAL PRESSURE & WIND
North Pole 90°N
Arctic circle 66.5°N
HIGH
HIGH PRESSURE
LOW
ZONE of greatest
heating produces
LOW PRESSURE
Tropic of Cancer
23.5°N
Equator 0°
Tropic of Capricorn
23.5°N
Antarctic circle 66.5°S
ZONE of least heating produces
HIGH
ZONE of least heating produces
HIGH PRESSURE
North Pole 90°N
How would you expect air to move across the planet?
High
Coriolis (Force) Effect
Wind blows from
areas of high pressure
to areas of low
pressure because of a
difference in pressure
called a pressure
gradient
The apparent
path of the wind
appears to curve
as a result of the
rotation of the
Earth
Low
Merry Go Round Demonstration
The Earth’s rotation diverts or
appears to turn the wind
direction sideways. This force is
called the CORIOLIS FORCE.
� The Coriolis force
diverts/turns wind the the right
in the northern hemisphere; to
the left in the south.
�
Trade
Westerlies
Winds
–
Easterlies
–
–pattern
patternofof
pattern of
air
air
air
movement
movement
movement
in
in
the
the midat the poles
tropics
latitudes
Goes to
to the
the
Goes
midequator
poles
latitudes
Image courtesy of
Santasusana.org
Ocean Currents Illustrated
Planet 100: The Pacific Trash
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