Winds of the World Global and Local Winds

Winds of the World Global and Local Winds 1

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

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

Westerlies l l Location: between 30 & 60 degrees latitude, in both N & S hemispheres Facts: – – 5 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

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

The Doldrums l l Location: 0 degrees latitude; @ equator Facts: – – – 9 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)

The Horse Latitudes l l Location: @ 30 degrees latitude in both hemispheres Facts: – – – 11 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

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

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Local Winds: l Types: – – 15 Land Breezes Sea Breezes Mountain Breezes Valley Breezes l l 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

Sea Breeze l l Location: air moves from the sea to the land Facts: (During the day) – – – 16 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.

Land Breeze l Location: air moves from the land to the sea l Facts: (During the night) – – – 17 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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Mountain Breeze l Location: cool air sinks from the mountain top into the valley below l Facts: – – 19 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.

Animation of mountain breezes 20

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

Animation of valley breeze 22

Higher Order Thinking Skills Questions (HOTS) 23 l How areas of high and low pressure created? l 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? l Why doesn’t the wind flow in one huge belt from the poles to the equator? l Why doesn’t wind blow directly north or south?