Winds of the World

1. Winds of the World Global and Local Winds

2. Global Winds Global winds are a part of air circulation that moves across the Earth. They are formed from the uneven heating of the Earth and the resulting pressure differences.

3. Polar Easterlies • Location: found from the poles down to 60 degrees latitude in N & S hemispheres • Facts: • Formed from cold, sinking air moving down from the poles • Responsible for the cold weather in the US

5. Westerlies • Location: between 30 & 60 degrees latitude, in both N & S hemispheres • Facts: • Flow toward the poles from west to east • Can carry moist air over the US, producing rain & snow • Helped settlers return to Europe • Influences your weather

7. Trade winds • Location: 30 degrees to the equator in both hemispheres • Facts: • Coriolis effect causes the trades to curve • Curve to west in NH • Curve to east in SH • Early traders used the TW to sail from Europe to America

9. The Doldrums • Location: 0 degrees latitude; @ equator • Facts: • Means dull or sluggish • Form where trade winds meet • Very little wind because the warm, rising air @ the equator creates an area of low pressure (remember air moves from high to low pressure, so there is NO wind if there is no high pressure)

11. The Horse Latitudes • Location: @ 30 degrees latitude in both hemispheres • Facts: • Sinking air creates an area of high pressure, creating weak winds • Legend says the horse latitudes got their name because the weak winds stranded horse-trading ships coming from Europe to America • To survive the sailors on the ships threw the horses overboard to save food and water

13. Jet Streams • Location: upper troposphere & lower stratosphere • Facts: • Narrow belts of winds • Do not follow regular paths • Can reach speeds of 400km/h • Affect the movement of storms & planes

15. Types: Land Breezes Sea Breezes Mountain Breezes Valley Breezes Local winds can move from any direction but only move short distances. They are formed from the uneven heating of the Earth and pressure differences Local Winds:

16. Sea Breeze • Location: air moves from the sea to the land • Facts: (During the day) • Air over water is cooler & creates high pressure. • Cool, dense air moves toward land, creating a sea breeze. • Air over land is warmer, so the warm air rises, creating low pressure over land.

17. Land Breeze • Location: air moves from the land to the sea • Facts: (During the night) • Air over land is cooler & creates high pressure. • Cool air moves toward the sea, creating a land breeze. • Air over the sea is warmer, so it rises creating low pressure.

19. Mountain Breeze • Location: cool air sinks from the mountain top into the valley below • Facts: • Mountain tops cool faster than valleys at night. • Cold air is dense (heavier) so it sinks from the mountain tops into the valleys below creating a mountain breeze.

20. Animation of mountain breezes

21. Valley Breeze • Location: warm air moves up the mountain from the valley below • Facts: • The sun heats the valley floor & warms the air above it. • The warm air rises creating a valley breeze.

22. Animation of valley breeze

23. Higher Order Thinking Skills Questions (HOTS) • How are areas of high and low pressure created? • Knowing that air moves from areas of high pressure to areas of low pressure, which direction should the winds of the Earth move—in what direction from where? • Why doesn’t the wind flow in one huge belt from the poles to the equator? • Why doesn’t wind blow directly north or south?