Atmospheric CirculationAtmospheric CirculationThe Coriolis Effect, Winds and The Coriolis Effect, Winds and

BreezesBreezesChapter 22.3Chapter 22.3

The Coriolis EffectThe Coriolis Effect• Air follows a curved path due to the Air follows a curved path due to the

rotation of the Earth. rotation of the Earth. • The faster an object travels, the The faster an object travels, the

greater the Coriolis Effect on the greater the Coriolis Effect on the object.object.

The Coriolis Effect and WindThe Coriolis Effect and Wind• Wind that blows from increased to Wind that blows from increased to

decreased pressure curve because of the decreased pressure curve because of the Coriolis Effect.Coriolis Effect.

• In the Northern Hemisphere winds curve In the Northern Hemisphere winds curve right.right.

• In the Southern Hemisphere winds curve In the Southern Hemisphere winds curve south.south.

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Global WindsGlobal Winds• Winds do not flow in a single straight Winds do not flow in a single straight

line. line. • Each Hemisphere has 3 patterns of Each Hemisphere has 3 patterns of

air flow (winds).air flow (winds).• Wind Belts: Area of the Earth Wind Belts: Area of the Earth

characterized by winds that flow in characterized by winds that flow in one main direction.one main direction.

• 6 wind belts- 3 in each Hemisphere.6 wind belts- 3 in each Hemisphere.• Winds are named by the direction Winds are named by the direction

the wind comes from.the wind comes from.

Trade WindsTrade Winds• Winds that flow towards the equator Winds that flow towards the equator

between 30between 30° and 0° latitude.° and 0° latitude.• N. Hemisphere called Northeast N. Hemisphere called Northeast

TradewindsTradewinds• S. Hemisphere called Southeast S. Hemisphere called Southeast

Trade Winds.Trade Winds.• Called trade winds because trading Called trade winds because trading

ships sailed on these winds during ships sailed on these winds during the 18the 18thth and 19 and 19thth centuries. centuries.

WesterliesWesterlies• Winds that flow between 30Winds that flow between 30° and 60° ° and 60°

latitude towards the poles.latitude towards the poles.• N. Hemisphere- southwest westerlieN. Hemisphere- southwest westerlie• S. Hemisphere- northwest westerlieS. Hemisphere- northwest westerlie• These winds are felt in the These winds are felt in the

continental U.S.continental U.S.

Polar EasterliesPolar Easterlies• Winds that blow from about 60Winds that blow from about 60° to 90° ° to 90°

(the poles) (the poles) • These winds are created by the polar These winds are created by the polar

high pressure and are deflected by the high pressure and are deflected by the Coriolis EffectCoriolis Effect

• Strongest over AntarcticaStrongest over Antarctica• Where the polar easterlies and the Where the polar easterlies and the

westerlies meet are regions called westerlies meet are regions called fronts.fronts.

Doldrums and Horse Doldrums and Horse LatitudesLatitudes• Areas where winds are weak and Areas where winds are weak and

variable.variable.• Doldrums are where tradewinds from Doldrums are where tradewinds from

N. and S. Hemisphere meet (at N. and S. Hemisphere meet (at equator).equator).

• Horse Latitudes are subtropical high Horse Latitudes are subtropical high pressure zones around 30pressure zones around 30° latitude.° latitude.

Jet StreamsJet Streams• Narrow bands of high speed winds Narrow bands of high speed winds

that blow high above the surface of that blow high above the surface of the Earth.the Earth.

• Can affect airline travelCan affect airline travel

The diagram below shows the different wind belts on The diagram below shows the different wind belts on Earth.Earth.

Local WindsLocal Winds• Wind we usually feel that cover less than Wind we usually feel that cover less than

100 km are called breezes.100 km are called breezes.• During the During the dayday, the land gets hotter , the land gets hotter

faster, and the hot air rises, creating an faster, and the hot air rises, creating an area of lower pressure. Wind blows from area of lower pressure. Wind blows from the sea to the land. This is a the sea to the land. This is a sea breezesea breeze. .

• At At nightnight, the land cools off faster than the , the land cools off faster than the sea. Cooler air descends creating an area sea. Cooler air descends creating an area of higher pressure. Wind blows from the of higher pressure. Wind blows from the land to the sea. This is a land to the sea. This is a land breezeland breeze. .

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