1. Chapter 9: Weather Factors
Section 3: Winds

2. What is Wind?
Wind – horizontal movement; from high pressure to lower pressure.
Caused from differences in pressure
Difference in pressure – caused by unequal heating of the atmosphere.

3. Measuring Wind Winds are described by their direction and speed.
Name of wind – Where it comes from

4. Measuring Wind
Wind speed is measured with an anemometer.

5. Wind-Chill Factor
Wind-Chill Factor – the increased cooling caused by wind.

6. Local Winds Local Winds – blow over short distances.
Caused by unequal heating of Earth’s surface within a small area.
Form only when large scale winds are weak.

7. Local Winds
Sea Breeze (Lake Breeze) – a local wind that blows from an ocean or lake.

8. Local Winds
Land Breeze – flow of air from land to a body of water.

9. Global Winds
Global Winds – winds that blow steadily from specific directions over long distances.
Created by unequal heating of Earth’s surface but occur over a large area.

10. Global Convection Currents
Global Convection Currents – Temperature differences between the equator and the poles produce giant convection currents in the atmosphere.

11. Global Convection Currents
Coriolis Effect – Earth’s rotation makes winds curve.

12. Global Wind Belts
Doldrums – Near Equator; Calm area; warm air rises; low pressure area
Horse Latitudes – Calm area; falling air; high pressure
Trade Winds – blow from horse latitudes toward the equator
Prevailing Winds – blow away from the horse latitudes toward the poles