Wind
Measuring Wind
Instruments –Anemometer (speed)
Wind Vane (direction)
And
Units: Knots (kts) or mi/hr
Named for the direction from which the wind
comes
Ex. SE wind – comes from the southeast
and blows toward the northwest
The aerovane (skyvane).
Definition
Horizontal movement of air due to
differences in air pressure due to the
unequal heating of the earth
Wind flows from High
to low pressure
Size of the pressure gradient dictates the
force of the wind. The higher the gradient,
the stronger the winds.
Global Winds
• What is the name we give motion due to
earth’s rotation?
________________________
Coriolis Effect
Because Earth is spinning, wind curves to
right
the ________
in the northern hemisphere
and to the left in the southern hemisphere
Global Winds
If earth did not spin,
the air movement
would look like this.
Air would rise at the
equator and sink at the
poles due to differences
in temperature
Global Winds
But the earth does spin,
so winds get deflected
to the right in the Northern
Hemisphere and to the
left in the Southern
Hemisphere.
Creates three Giant circulation cells
in each Hemisphere
ESRT Page 14
Will do more with this in the climate unit
As air moves from high to low pressure in the
northern hemisphere, it is deflected to the right
by the Coriolis force
• http://eram.k12.ny.us/education/page/dow
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• http://eram.k12.ny.us/education/page/dow
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11
Low and High Pressure Systems
Low Pressure System = Cyclone
Winds are counterclockwise
and inward
Winds converge or go into
the center
Air is forced up, expands,
cools to dew point, condenses
and clouds form
Jet Stream
• Area of high wind speeds in the upper
troposphere. The jet stream generally
moves __________
WEST
to __________
EAST
• Jet Streams steer storms
Most low pressure systems move from the
SOUTHWEST TO NORTHEAST IN NEW YORK STATE,
ESRT p14
High Pressure = Anticyclone
Winds are clockwise
and outward
High pressure is more dense
so air sinks
Winds diverge or move away
from the center
High Pressure is associated
with fair/nice weather
LOCAL BREEZES
• Sea/Land Breezes – caused by the
unequal heating of land and water
• Water heats up longer because of its high
specific heat
• Land heats up quicker due to its lower
specific heat
Sun heats
the land
Air is cooler
over ocean
Warm air
rises b/c
less dense
Air is
more dense
wind
High
pressure
Low
pressure
Sea Breeze
Sun is down
Air is warmer
over ocean
Land cools
down quicker
Air is less
dense
wind
Air is more
dense
Low
Pressure
High
Pressure
Land Breeze
• http://www.youtube.com/watch?v=uBqohR
u2RRk
• http://www.youtube.com/watch?v=9DNbkq
Vu2CE&feature=related
Do not play
• http://www.youtube.com/watch?v=_36MiC
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• More coriolis on utube
• http://ww2010.atmos.uiuc.edu/(Gh)/guides
/mtr/fw/crls.rxml