Local and Global WindsLocal and Global Winds

► AIMAIM: How is wind created?: How is wind created?

Do Now:Do Now:

►Recall what creates areas of higher Recall what creates areas of higher and lower air pressure.and lower air pressure.

►**FACT****FACT** Higher pressure air (Higher pressure air (HH) is cooler, more ) is cooler, more

clear, and drier than Lower pressure air clear, and drier than Lower pressure air ((LL) which is warmer, cloudier, and more ) which is warmer, cloudier, and more moist.moist.

VocabularyVocabulary

► Air pressureAir pressure► Local windsLocal winds► Global windsGlobal winds► Prevailing westerliesPrevailing westerlies► IsobarsIsobars► CyclonesCyclones► Anti-cyclonesAnti-cyclones

► Wind Chill factorWind Chill factor► AnemometerAnemometer► Wind VaneWind Vane

1. What is wind?1. What is wind?►WindWind – the horizontal movement of air – the horizontal movement of air

►***Wind is created when the uneven ***Wind is created when the uneven heating of Earth’s surfaces creates heating of Earth’s surfaces creates areas of high and low pressure***.areas of high and low pressure***.

►Air likes to move from Air likes to move from Higher pressure (H) to Lower pressure Higher pressure (H) to Lower pressure (L)(L)

2. How is wind named and 2. How is wind named and measured?measured?

► Named by the direction Named by the direction and speed from which and speed from which it comes. Ex. Westerly it comes. Ex. Westerly wind comes from the wind comes from the WestWest

► AnemometerAnemometer – – measures wind speed measures wind speed using cups connected using cups connected to a speedometerto a speedometer

► Wind vaneWind vane – points to – points to direction that wind direction that wind comes fromcomes from

3. What are local winds?3. What are local winds?

a. Local windsa. Local winds blow over short distances. blow over short distances.

b. Part of the weather report. b. Part of the weather report. weather.comweather.com

c. Examples: Land breezes, sea breezesc. Examples: Land breezes, sea breezes► Observe an animation of land and sea breezObserve an animation of land and sea breez

es.es.

4. Sea and Land Breezes4. Sea and Land Breezes► During day, warmer During day, warmer

air rises over the air rises over the sand, cooler air sinks sand, cooler air sinks over sea.over sea.

► Air moves from water Air moves from water to land = sea breezeto land = sea breeze

► During night, cooler During night, cooler air sinks over the air sinks over the sand, warmer air sand, warmer air rises over sea.rises over sea.

► Air moves from land Air moves from land to sea = land breezeto sea = land breeze

H HLL

Sea and Land breezes are local winds Sea and Land breezes are local winds that affect us near TOBAY or Jones that affect us near TOBAY or Jones

BeachBeach

5. Larger local breezes5. Larger local breezes

► MonsoonMonsoon – sea or – sea or land breezes land breezes covering a large covering a large area that change area that change directions with the directions with the seasons (Southeast seasons (Southeast Asia)Asia)

MonsoonsMonsoons

► WinterWinter: A large : A large land breeze, sinking land breeze, sinking higher pressure air higher pressure air over land keeps over land keeps moist air off shore moist air off shore =Good weather=Good weather

► SummerSummer: A large : A large sea breeze, rising, sea breeze, rising, moist air from over moist air from over the ocean blows the ocean blows onto land = Bad onto land = Bad weather, rainweather, rain

6. Global 6. Global WindsWinds

► Global windsGlobal winds blow over blow over a long distance from a a long distance from a specific directionspecific direction

► Created by uneven Created by uneven heating of equator and heating of equator and poles poles H H = poles, cool, sinking= poles, cool, sinking LL = equator, warm, = equator, warm,

risingrising

► Weather patterns are Weather patterns are affected by the affected by the prevailing windsprevailing winds in an in an area.area.

Name the prevailing winds that Name the prevailing winds that affect each area…ESRT pg 14affect each area…ESRT pg 14

► LatitudeLatitude – – distance from distance from EquatorEquator

► Horse latitudesHorse latitudes – – areas where air areas where air sinks, at 30°N and sinks, at 30°N and 30°S 30°S

► DoldrumsDoldrums – areas – areas with little wind (at with little wind (at the Equator)the Equator)

7. Global Convection Currents7. Global Convection Currents

► Poles have higher Poles have higher pressure (cold air)pressure (cold air)

► Equator has lower Equator has lower pressure (warmer pressure (warmer air)air)

► Air sinks from poles Air sinks from poles Equator creating Equator creating convection cellsconvection cells

Bands of H and L air are Bands of H and L air are createdcreated

The convection currents create The convection currents create a distribution system for earth’s a distribution system for earth’s

heatheat

http://www.youtube.com/watch?v=QbvHglFyZbg&playnext=1&list=PL9014F9D947576497

8. Why do the winds curve?8. Why do the winds curve?a.a. The Earth’s The Earth’s

rotationrotation curves curves the global winds.the global winds.

► Right in the Northern Right in the Northern hemispherehemisphere

► Left in the Southern Left in the Southern hemispherehemisphere

a.a. This is called This is called Coriollis Effect.Coriollis Effect.

► Coriolis Force: an artifact of the Coriolis Force: an artifact of the earth's rotationearth's rotation

► Observe an animation of the Observe an animation of the Coriolis effect over Earth's Coriolis effect over Earth's surface.surface.

9. Jet Streams9. Jet Streams►Jet streamJet stream – bands of high speed – bands of high speed

windswinds► 200 to 400 kilometers/hour200 to 400 kilometers/hour► Up near the TropopauseUp near the Tropopause► Can “stear” weather and pollution patternsCan “stear” weather and pollution patterns

http://www.youtube.com/watch?v=CgMWwx7Cll4

http://www.youtube.com/watch?v=UFC6819LS5w&feature=related

ESRT pg 14.ESRT pg 14.

Question…Question…

►Why do you think there are bands of Why do you think there are bands of wet and dry air at the equator, 30wet and dry air at the equator, 30oo, 60, 60oo and 90 and 90 oo??

10. Wind Chill factor10. Wind Chill factor► Wind chill factorWind chill factor – increased cooling, increased – increased cooling, increased

evaporation, make the temperature feel colder. evaporation, make the temperature feel colder. The stronger the wind, the colder you feel!The stronger the wind, the colder you feel!

Summary: What affect do Summary: What affect do winds have on weather?winds have on weather?

a.a. Moves weather Moves weather

b.b. Creates weather patterns (seasonal Creates weather patterns (seasonal changes)changes)

c. Increases evaporation (dry things out)c. Increases evaporation (dry things out)

d. Creates a wind chill (colder d. Creates a wind chill (colder temperatures)temperatures)

http://www.youtube.com/watch?v=kPueXIHGQrg&feature=related

http://www.youtube.com/watch?v=fYfrWLhZy1A&feature=related

Pressure, Wind and WeatherPressure, Wind and Weather

Maps show us where the rising Maps show us where the rising and sinking air is…..and sinking air is…..

High vs. Low AirHigh vs. Low Air

HighHigh: Anticyclone: Anticyclone

Clockwise, outwardClockwise, outward

More denseMore dense

Air sinks Air sinks

Good weather Good weather

Dry air Dry air

► Lows : CyclonesLows : Cyclones

Counter clockwise, Counter clockwise, inward Less Denseinward Less DenseRising airRising airMoist airMoist airBad weatherBad weather

Warm air rises, cool air sinksWarm air rises, cool air sinks

IsobarsIsobars

► Isobars are lines on Isobars are lines on a map that connect a map that connect areas of equal air areas of equal air pressure. pressure.

► Same rules apply….Same rules apply…. Connect equal valuesConnect equal values Calculate gradientCalculate gradient Steep side where Steep side where

lines are closest lines are closest togethertogether

Air moves from H to LAir moves from H to L

Pressure gradientsPressure gradients

►Pressure Gradient - the change in air pressure with distance.

►The windiest areas have the steepest gradients.

►Calculate the gradient between A – B and C – D on the following map

A

BD

C

Wind barbsWind barbs

► Tell us direction and Tell us direction and speed.speed.

The wind is blowing from the southeast at 15-20 mph

Draw the isobarsDraw the isobars

In the plotted station model the 3 digit number to the upper right of the station circle is the barometric pressure.

It will look like 196 for pressures 1000 millibars and higher: and 992 for pressures below 1000.

So, 196 means 1019.6 mb and 992 means 999.2 mb. Basically, add a 10 in front of anything starting with a 0 or 1, and a 9 for anything starting with a 9.

Convert each station and then draw the isobars.1016, 1012, 1008 and 996, 1004, 1008

Barometric pressure on station Barometric pressure on station modelsmodels

HL

1004 mb

1000 mb

996 mb

1008 mb

1012 mb

1016 mb