Wind Notes:

Remember …

• Air has mass and takes up space.

• Air pressure – the mass of the air being pulled down on an area of the earth’s surface.

• It pushes in all directions - it does not crush objects

Factors that affect Air Pressure:

1. Temperature

2. The amount of air above it

3. How fast it is moving

Wind:Horizontal movement of air (fluid) from an area of high pressure to

low pressure

High Pressure Low Pressure

exampleA

B

A to B movement= NO ENERGY (wind)

B to A movement= ENERGY (fan)

Wind facts:

1) The greater the pressure difference, (temp difference)The greater the WIND!

2) Described by original direction and speed

ex: Northeastern wind at 50mph

Measurement of Wind:1) Wind vane- measures wind direction

2) Anemometer:

measures wind speed

3) Wind-chill factor: increased cooling caused by the wind* cool breeze blowing by skin

removes heat

Two Types:1)Local Winds

2)Planetary (or Global) Winds

Local Wind:

effect small areas (beach, lake)1) SEA BREEZE

P P

landwater

Blue = Cool Red = Warm

SEA BREEZE* Land heats faster than the water

Air above land heats faster

• Warm air rises creating LOWER pressure over land

• High Pressure over water

COOL air moves TOWARD LAND= CLOCKWISE

2).Land Breeze

P P

landwater

LAND BREEZE

• Land cools faster than water

• Pattern of circulation is reversed

• Air moves toward water»COUNTERCLOCKWISE

Coriolis Force/Effect:• Due to Earth’s rotation,

– Winds in Northern Hemisphere curve to the RIGHT = CLOCKWISE

– Winds in Southern Hemisphere curve to

The LEFT= COUNTERCLOCKWISE

NH

SH

equator

PLANETARY/GLOBAL WINDS

*Caused by: Uneven heating of Earth’s surface

*Warm air rises at the equator and

*Cold air sinks at the poles

Major Wind Systems• 1) Trade Winds:- steady winds blowing to

the southwest. Ships used them (“traders”) to travel with goods.

• 2) Prevailing Westerlies:-blow from southwest to northeast. Moves WEATHER

across the United States and Canada

• 3) Polar Easterlies:- due to the Coriolis effect,

winds at North pole rotate clockwise. Winds at the South pole rotate counterclockwise

4) Jet Stream:- fast moving streams of air

higher than other wind systems.

Narrow and Strong

Pilots use them

• 5) Doldrums:- windless zone at the equator. (remember CONVECTION)

• 6) Horse Latitudes:- windless zone at 30 North and 30 south latitudes

(Tropic of Cancer/Tropic of Capricorn)

Diagram of winds