Global and Local WindsGlobal and Local Winds

Air MovementAir Movement

•WindWind is the movement of is the movement of air caused by differences air caused by differences in air pressurein air pressure

•The The greatergreater the the difference, the difference, the fasterfaster the the wind moveswind moves

Air PressureAir Pressure

•Differences in air pressure Differences in air pressure are caused by the are caused by the uneven uneven heatingheating of Earth of Earth

•Uneven heating produces Uneven heating produces pressure beltspressure belts which which occur every 30occur every 30° latitude° latitude

Pressure BeltsPressure Belts

•As As warm airwarm air rises at the rises at the equator and moves toward equator and moves toward the poles, it coolsthe poles, it cools

•As it cools, some of the air As it cools, some of the air sinks around sinks around 3030° north ° north and southand south of the equator of the equator

Pressure BeltsPressure Belts

•At the poles, At the poles, cold air cold air sinkssinks and moves towards and moves towards the equatorthe equator

•Around Around 6060° north and ° north and southsouth, the air begins to , the air begins to heat up and riseheat up and rise

Global WindsGlobal Winds

•The combination of pressure The combination of pressure belts and the Coriolis Effect belts and the Coriolis Effect cause cause global windsglobal winds

•These are These are polar polar easterlies, westerlies, easterlies, westerlies, and trade windsand trade winds

Polar EasterliesPolar Easterlies

•Wind belts that extend from Wind belts that extend from the the poles to 60poles to 60° latitude° latitude

•Formed from cold sinking Formed from cold sinking air moving from the poles air moving from the poles creating creating cold cold temperaturestemperatures

WesterliesWesterlies

•Wind belts found Wind belts found between between 3030° and 60° latitude° and 60° latitude

•Flow towards the poles from Flow towards the poles from west to east carrying west to east carrying moist moist airair over the Unites States over the Unites States

Trade WindsTrade Winds

•Winds that blow from Winds that blow from 3030° ° almost to the equatoralmost to the equator

•Called the trade winds Called the trade winds because of their use by because of their use by early sailorsearly sailors

DoldrumsDoldrums

•Located along the Located along the equator where equator where no winds no winds blowblow because the warm because the warm rising air creates and rising air creates and area of low pressurearea of low pressure

Horse LatitudesHorse Latitudes

•Occur at about 30Occur at about 30° north and ° north and south of the equator where south of the equator where the winds are the winds are very weakvery weak

•Most deserts on the Earth Most deserts on the Earth are located here because of are located here because of the the dry airdry air

Jet StreamJet Stream

•The jet streams are The jet streams are narrow belts of narrow belts of high high speed windsspeed winds that blow that blow in the upper troposphere in the upper troposphere and lower stratosphereand lower stratosphere

•SeparatesSeparates warm air warm air from cold airfrom cold air

Local WindsLocal Winds

•Generally move Generally move short short distancesdistances and can blow in and can blow in any directionany direction

•Caused by Caused by geographic geographic featuresfeatures that produce that produce temperature differencestemperature differences

Sea BreezesSea Breezes

•High pressure is created over High pressure is created over the ocean during the day and the ocean during the day and low pressure over land due to low pressure over land due to uneven heatinguneven heating

•Air moves from the ocean to Air moves from the ocean to the land creating a the land creating a sea breezesea breeze

Land BreezesLand Breezes

•Low pressure occurs over the Low pressure occurs over the ocean ocean during the nightduring the night and and high pressure over land due to high pressure over land due to the uneven heating of earththe uneven heating of earth

•This causes wind to move from This causes wind to move from the land to the ocean creating a the land to the ocean creating a land breezeland breeze

Question 1Question 1

•What causes winds?What causes winds?

AnswerAnswer

•Winds are caused by Winds are caused by the uneven heating of the uneven heating of Earth’s surface, which Earth’s surface, which causes pressure causes pressure differencesdifferences

Question 2Question 2

•What are the three What are the three types of global winds?types of global winds?

AnswerAnswer

•Polar EasterliesPolar Easterlies

•WesterliesWesterlies

•Trade WindsTrade Winds

Question 3Question 3

•What is the What is the difference between a difference between a land breeze and a sea land breeze and a sea breeze?breeze?

AnswerAnswer

•Sea breezes occur during Sea breezes occur during the day when the land is the day when the land is warmer than water and a warmer than water and a land breeze occurs at land breeze occurs at night when the water is night when the water is warmer than landwarmer than land