Wind

Ch.2 Sec. 3

What is wind?

• The horizontal movement of air

• Caused by differences in air pressure

• Air moves from high to low

• These differences in air pressure result from uneven heating–Hot air = less dense = lower

pressure

–Cold air = more dense = higher pressure

• If a cooler area is next to a warmer area the air will flow from cool to warm

• Cooler air tends to be lower down so it flows under warmer air–Warmer air gets pushed up

Measuring wind• Two properties

–Direction

–Speed

Wind direction• Measured with a wind vane• Vane points to where wind is

coming from• This direction give wind its

name–Ex. A north wind blows from the

north to the south

Wind speed

• Measured with an anemometer–Wind causes it to spin

–Speedometer measures speed of spinning

Effect of wind

• Can affect how warm/cold it feels outside

• Wind-chill factor–Increased cooling due to wind

–The stronger the wind the colder it feels

Types of Winds

• Local winds

• Monsoons

• Global winds

• Jet streams

Local winds

• Blow over short distances

• Caused by unequal heating within a small area

• Only happen if no wind from farther away

• Often felt near bodies of water

• Water heats and cools more slowly than land

• During the day land is warmer than water wind from water–Sea breeze

• At night the water is warmer than land wind towards water–Land Breeze