1. Winds of the World Global and Local Winds
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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.
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3. Used with permission of V. Morris, Phillips Preparatory School
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
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4. Used with permission of V. Morris, Phillips Preparatory School

5. Used with permission of V. Morris, Phillips Preparatory School
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
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6. Used with permission of V. Morris, Phillips Preparatory School

7. Used with permission of V. Morris, Phillips Preparatory School
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
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8. Used with permission of V. Morris, Phillips Preparatory School

9. Used with permission of V. Morris, Phillips Preparatory School
The Doldrums
Location: 0 degrees equator
Facts:
Means dull or sluggish
Form where trade winds meet
Very little wind because the warm, rising 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)
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10. Used with permission of V. Morris, Phillips Preparatory School

11. Used with permission of V. Morris, Phillips Preparatory School
The Horse Latitudes
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
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12. Used with permission of V. Morris, Phillips Preparatory School

13. Used with permission of V. Morris, Phillips Preparatory School
Jet Streams
Location: the upper & lower atmosphere (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
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15. Used with permission of V. Morris, Phillips Preparatory School
Local Winds:
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
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16. Used with permission of V. Morris, Phillips Preparatory School
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.
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17. Used with permission of V. Morris, Phillips Preparatory School
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.
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18. Used with permission of V. Morris, Phillips Preparatory School

19. Used with permission of V. Morris, Phillips Preparatory School
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.
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20. Animation of mountain breezes
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21. Used with permission of V. Morris, Phillips Preparatory School
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.
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22. Animation of valley breeze
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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?
Warm air rises creating areas of low
pressure and cold air sinks creating areas of high pressure. Pressure depends on the density of the molecules; remember cold air is denser than warm air.
Warm air rises creating areas of low pressure and cold air sinks creating areas of high pressure. Pressure depends on the density of the molecules; remember cold air is denser than warm air.
Air moves from areas of high pressure to areas to low pressure, so wind generally moves from the poles to the equator.
Warm air cools and sinks; cools and sinks, every 30 degrees creating pressure belts from pole to equator to pole.
Used with permission of V. Morris, Phillips Preparatory School