1. Winds Chapter 2, Section 3 p. 52-60

2. What causes wind? Wind: The horizontal movement of air from an area of high pressure to an area of lower pressure.

3. What causes winds? All winds are caused by differences in air pressure HIGH  LOW

4. What causes these differences in pressure? Unequal heating of the atmosphere Remember convection currents? As air becomes less dense, its air pressure decreases.

5. Measuring Wind Winds are described by their direction and speed

6. Measuring Wind To measure wind direction: we use a wind vane

7. Measuring Wind To measure wind speed: we use an anemometer

8. Wind- Chill Factor Wind Chill Factor: Increased cooling caused by the wind

9. Local Winds Local winds: winds that blow over short distances

10. Local Winds Local winds are caused by unequal heating of Earth’s surface within a small area

11. Local Winds Example: cool breezes blowing in from the water to the beach.

12. Sea Breeze Sea Breeze:The flow of air from an ocean or lake to the land. Daytime!

13. Land Breeze Land Breeze: The flow of air from land to a body of water. Night time!

14. Land Breeze/ Sea Breeze

15. Monsoons Monsoons: Sea and land breezes over a large region that change directions with seasons

16. Global Winds Global Winds: Winds that blow steadily from specific directions over long distances

19. Temperatures Temperatures near the equator are much warmer than the temperatures near the poles.

20. Intermission Chapter 2, Section 3 p. 57-60

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

22. This movement of air between the equator and the poles produces global winds. Global Convection Currents

23. Coriolis Effect: The way Earth’s rotation makes winds curve. Give students this analogy: Assume a plane takes off from some northern location in the U.S. (pick one from your area) and flies several hours due south (pick another location). When the plane arrives, the destination city has moved east due to the Earth’s rotation. To really reach the destination due south, the plane actually has to fly a curved path to where the city will be when the plane lands. This is what happens with the air “turning to the right.” The Coriolis Effect

24. In the Northern Hemisphere In the Southern Hemisphere Global winds turn toward the RIGHT Global winds turn toward the LEFT

25. The 3 major wind belts are the: 1. trade winds 2. prevailing westerlies 3. the polar easterlies Global Wind Belts

26. The 2 calm areas are the: 1. Doldrums 2. Horse Latitudes Global Wind Belts

28. A calm area where warm air rises Regions near the equator with little or no wind Doldrums

29. A calm area of falling air Latitudes 30 ◦ north and south of the equator Horse Latitudes

30. Steady easterly winds which blow from the horse latitudes toward the equator. Trade Winds

31. Winds in the mid latitudes which blow from the west to the east. Play an important part in the weather of the United States Prevailing Westerlies

32. Cold air near the poles which sinks and flows back toward lower latitudes. Polar Easterlies

33. Global Wind Belts

34. Jet Streams: Bands of high-speed winds about 10 kilometers above Earth’s surface Jet Streams