Global and local winds

1. Global and Local WindsGlobal and Local Winds

2. Air MovementAir Movement
•WindWind is the movement is the movement
of air caused by of air caused by
differences in air pressuredifferences in air pressure
•The The greatergreater the the
difference, the difference, the fasterfaster the the
wind moveswind moves

3. 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

5. 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

6. Pressure BeltsPressure Belts
•At the poles, At the poles, cold air cold air
sinkssinks and moves and moves
towards the equatortowards the equator
•Around Around 6060° north and ° north and
southsouth, the air begins to , the air begins to
heat up and riseheat up and rise

7. 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

9. 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 air Formed from cold sinking air
moving from the poles moving from the poles
creating creating cold cold
temperaturestemperatures

11. WesterliesWesterlies
•Wind belts found Wind belts found between between
3030° and 60° latitude° and 60° latitude
•Flow towards the poles Flow towards the poles
from west to east carrying from west to east carrying
moist airmoist air over the Unites over the Unites
StatesStates

13. Trade WindsTrade Winds
•Winds that blow from Winds that blow from
3030° almost to the ° almost to the
equatorequator
•Called the trade winds Called the trade winds
because of their use by because of their use by
early sailorsearly sailors

15. DoldrumsDoldrums
•Located along the Located along the
equator where equator where no no
winds blowwinds blow because because
the warm rising air the warm rising air
creates and area of low creates and area of low
pressurepressure

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

17. 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

19. Local WindsLocal Winds
•Generally move Generally move short short
distancesdistances and can blow and can blow
in any directionin any direction
•Caused by Caused by geographic geographic
featuresfeatures that produce that produce
temperature differencestemperature differences

20. 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 sea
breezebreeze

22. 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 the land to the ocean creating
a a land breezeland breeze

24. Question 1Question 1
•What causes winds?What causes winds?

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

26. Question 2Question 2
•What are the three types What are the three types
of global winds?of global winds?

27. AnswerAnswer
•Polar EasterliesPolar Easterlies
•WesterliesWesterlies
•Trade WindsTrade Winds

28. Question 3Question 3
•What is the difference What is the difference
between a land breeze between a land breeze
and a sea breeze?and a sea breeze?

29. 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