Wind
I.
Definition
A. Wind is the HORIZONTAL movement of
air from an area of high pressure to an
area of low pressure.
B. There are two general types of winds:
local and global winds
C. Both local and global winds are caused
by differences in air pressure due to
unequal heating of the Earth’s surface
and air above it.
Wind
II. Local Winds
A. Wind movement over short distances from
any direction.
B. Types of local winds:
1. Sea Breeze: Flow of air from the
sea to the land due to the land
absorbing more heat than the water
during the day.
Wind
Daytime
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land absorbs the suns energy and releases it
water absorbs the suns energy and holds it
hot air rises over the land
cooled air sinks over the water
Comes back to land as a SEA BREEZE.
Wind
2. Land Breeze: The flow of air from land to sea due
to the cooler air over the land moving to replace the
rising air over the water at night.
Night Time
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water releases heat gathered during the day
hot air rises over the water
cooled air sinks over the land
Moves out over the water as a LAND BREEZE.
Wind
3.
Monsoon: Seasonal wind – a major sea or
land breeze.
C. All winds are named for the direction FROM
which they come!
Example: A wind coming from the northwest blows
toward the southeast, but is named a northwest
wind!
II. Measuring Local Wind
A. Wind speed is measured with an anemometer.
B. Wind direction is measured with a weather/wind
vane.
Wind
III. Global Winds
A. Unequal heating of the earth’s surface forms
global wind patterns.
B. Travel over large areas of the earth and only
come from one direction.
C. Due to the earth’s rotation, the global winds are
curved and shift in relation to the earth’s surface.
D. CORIOLIS EFFECT: The way the earth’s rotation
makes winds curve. Winds curve in the opposite
direction north and south of the equator.
Wind
Wind patterns as if the earth were standing still (No Coriolis
Effect).
Wind
E. Types of Global Winds:
1. Doldrums – Located at the equator, these winds are
calm with little horizontal movement
2. Horse latitudes - 300 north and south of the equator
3. Trade winds – global winds between 300 north and
south and the equator; used to be used by sailors long
ago to move their ships carrying cargo (trade)
4. Prevailing Westerlies – global wind that affects the
United States and causes our weather to move from west
to east.
5. Polar Easterlies – Global winds located at the north
and south poles.
Wind
Same wind patterns as before, now they have direction to them.
Polar easterilies
**Prevailing Westerlies
North Trade
Doldrums
South Trade
Westerlies
Polar Easterlies
We (United States) are in the Prevailing Westerlies Wind Belt