Science EQ: What causes the wind to blow?

Do Now: 3-4

LG: Explain the difference between air pressure and wind direction? Describe global wind patterns.

HW: Study Global Wind notes, Review quiz correct answers. 15-3 Dir. Reading check Friday

1. Take out blue and read colored pencils/markersToday~ papers back – make-up work??~ Visual Organizer: Global Winds

What causes winds?• horizontal movement area of high to low pressure.• Unequal heating of atmosphere = different temps• Different temps = different air pressure

High PressureLow Pressure

WIND

Low Pressure

WIND

Earth’s Surface

Global Winds• Winds that blow steadily from specific directions

are global winds.• Created by unequal heating of Earth’s surface.• Warm air rises at the equator and falls at the

poles.

Air Rises @ EquatorAir Sinks @ Poles

• You know… – Warm air rises = less dense– Cool air sinks = more dense

• Now understand…–Warm air = less dense

= low pressure–Cool air = more dense

= high pressure

Measuring Wind

• Winds are described by their direction and speed.

• Wind direction is determined with a wind vane – points in the direction the wind is moving!

• Wind speed is measured with an anemometer.

• The increased cooling that a wind can cause is called the wind chill factor.

Anemometer – The cups catch the wind, turning faster when the wind blows faster.

Wind Vane

Info… via Video…

Global Winds… cont… • The movement of air

between the equator and the poles produces global winds.

• The way that Earth’s rotation makes winds curve is called the coriolis effect.

= pattern of the Global Winds

Global Wind Belts• The five global

wind belts are 1. doldrums2. horse latitudes3. trade winds4. prevailing westerlies5. polar easterlies.

Jet Streams• Bands of high speed winds• Upper troposphere and

lower stratosphere• Blow from west to east at

speeds of 200-400 km/hr.• Help airplanes save fuel

and time when traveling east.

Global Wind Belts• Major global wind systems:• Polar easterlies, westerlies, and trade winds.

Doldrums• Where the trade winds meet around the equator• Very little wind because the warm air rising =

low pressure

Horse Latitudes• High pressure areas… 300N and 300S• Very week winds

Wrap UP!

Local WindsHave you ever flown a kite at the beach on a hot summer day?

Even if there is no wind inland, there may be a cool breeze blowing in from the water toward the beach. This breeze is an

example of local winds!

• Local winds are winds that blow over short distances.

• They are caused by unequal heating of Earth’s surface within a small area.

• 2 Types of local winds: –sea breezes and land breezes

Sea Breeze (Morning)

Land heats up faster than water. Hot air over land rises (Low Pressure), cool air over water falls (High Pressure). Winds move from the water (High Pressure) to the land (Low Pressure).

Land Breeze (Evening)

Land cools off faster than water. Cool air over land falls (High Pressure), warm air over water rises (Low Pressure). Winds move from the land (High Pressure) to the water (Low Pressure).