AAtmtmosposphericheric aanndd OOceceananiicc CirculatCirculatioionn

AtmoAtmossppherheriicc cciirrculationculation ttranransferssfers energenergyy andand massmass overover thethe EarthEarth . Redistributes surplulus energy alonlong the tropics to deficicitit areas . Generates weather patterns . Produces ocean currents . Spread naturall and anthropogenic pollllutiion

WhatWhat isis aatmtmososppherhericic ppresressuresure??

AAttmospmospherihericc PresPressusurree

AAirir prpressureessure –– prpressuressuree exexerertedted oonn thethe surfsurfaceace ofof thethe eartearthh byby thethe aatmosptmosphere.here.

. Motiion, siize and number of air moleculeles withiithin the atmosphere determiine the temperature and densityity of airir . Temperature and densitity of airir determine the pressure it exerts on the surface . Air pressure iis caused by the force of graviity pulllinling the mass of the atmosphere toward the surface of the earth

WhatWhat dedetermterminineses aatmtmososppherhericic ppressressuurere??

AtmAtmoosspphheericric PPrressessuurree

-Pressure = force per unit area

-Due to gravity the atmosphere exerts a force

 AcAcccordingording toto ththee IdIdealeal GasGas LawLaw:: dendensisittyy ((ρρ)) andand temtemperaperaturturee (T)(T) cocontrolntrol atmoatmospherspheriicc pressupressurere ((PP))

PP == ρρRTRT

RR == aa conconststanantt

PressurPressure,e, DenDensisittyy && TemTemperaperatureture

DensityDensity ((ρρ))

 Amount of matter (mass) per unit volume (kg/m3)

 Densiity (of a gas) isis dirirectlly proportiionall to pressure

 Densiity varies withith alaltititude

PressurPressure,e, DenDensisittyy && TemTemperaperatureture

Temperature (T)  Moleculeles move faster iin hot airir tthan cold airir

 Faster = more collillisions (more force) and therefore higher pressure

 Temperature is direirectlyly proportioional to pressure

PressurPressure,e, DenDensisittyy && TemTemperaperatureture

 In the atmosphere densityity and temperature do not change inindependentlyly

Examplele:

When air inin the atmosphere isis heated iit expands and causes a decrease inin densitity and pressure

HHooww iiss atatmomossphphericeric prepressssuurere mmeaeassuuredred??

AAtmtmospheosphericric PressurPressuree

 Atmosphericic pressure iis often measured iin miillillibars (mb)

 Atmosphericic pressure at sea lelevell isis 1013.25 millibibars (standard pressure)

 At the earth’s surface, pressure varies from 980 mb to 1030 mb (about 5%)

AtmoAtmossppherheriicc PrPressureessure:: In 1643, a student of Galilileleo, Evangelilista Torricellilli develoloped a method for measuring airir prepressure whilile trying to drainin mines.

. Noticiced that water llevels wiithin miines varied dailyly . Arrivedived at the theory that the downward force of the atmosphere on the water surface also flluctuated →days of higigher air pressure caused lolower water lelevells witithinin mines

MMeeasasururemementent ofof AAtmtmosospphehericric PrePressssurure:e:

 Atmosphericic pressure iis measured usiing and iinstrument calllled a barometer

 A mercuriall barometer measures atmospheric pressure wiith a colulumn of mercury

 Sea-levell pressure (1013mb) alslso can be definined as 29.92 ininches of mercury (in. Hg)

AAttmospmospherihericc PresPressusurree

 A more common type of barometer isis the aneroid barometer

 It uses the pressure exerted agaiinst a partiall vacuum to measure airir pressure

Note:Note: decrdecreaseease iinn airair ppressurressuree withwith iinnccrreaseease iinn elevatioelevationn

- DecreaDecreasese boilingboiling pointpoint ooff waterwater - 0 m  100 C - 3000 m  90 C - 5000 m  80 C - IncrIncreaseease iinn cookingcooking timestimes atat higherhigher elevatelevationsions

WWinindd

WindWind –– horhoriizonzontaltal momovemenvementt ofof airair . Produced by differences iin air pressure from one lolocatiion to another . Air moves from locatiions of high pressure to locatiions of lolow pressure

Measurement: wiind has two principipall components - Speed (anemometer) - Diirectiions (wiind vane)

Wind Vane: -Points in the direction air is moving -Wind is named based on the direction from which it originated -Designated by compass directions

ForcForceess DDrriviviningg AtmAtmososphpherericic MMotiotionon

FFoourur forceforcess affectaffect thethe directdirectiioonn andand speedspeed ofof airair (wind)(wind) asas itit mmovesoves thrthrougoughouthout thethe atatmospmospherehere::

3. GrGravitationavitationalal forcforcee 4. PressurPressuree ggradientradient forforcece 5. CoriolisCoriolis foforcerce 6. FFrrictioniction

1)1) GrGraviavitty:y: . Draws the mass of the atmosphere towards the surface of the earth . Causes decrease inin pressure and mass witith iincreasing elelevatiion . Wouldld not have an atmosphere or airir prpressure witithout iit

2)2) PressurPressuree GrGradientadient FFororce:ce: aaiirr momovesves frfromom hhiigghh prpressureessure reregionsgions toto lowlow prepressuressure

. Variatioions in airir pressure are caused by uneven heatining of the earth’’s surface.

UnevUnevenen heaheatingting ofof thethe eartearth’sh’s surfsurfaceace

Warm surfaces encourage upward verticical motiion

Upward airflow

Converging Converging Horizontal Air Low pressure Horizontal Air area

Warm S urface UnevUnevenen heaheatingting ofof thethe eartearth’sh’s surfsurfaceace

As airir molecules cool,l, they condense and decend towards the surface

Air Cools

Diverging Diverging Horizontal Air High pressure Horizontal Air area

LineLiness ofof eqequalual prpressuressuree areare isobarisobars:s:

- b/c air moves from high to lolow pressure, the PGF isis exerted at 90º angleles from the iisobars - When isobars are cllose together the pressure gradieient isis higigher → stronger wininds - When isobars are farther apart the pressure gradieient is llower → weaker wininds

3)3) CoriolisCoriolis FFoorce:rce: airair flowflow iiss deflectedeflectedd frfromom aa straigstraightht patpathh byby thethe rotrotationation ooff thethe earearthth

. Earth’s’s rotatioional speed iincreases from the poles toward the equator  0km /hr at the poles, 1675km /hr at equator  Defllection iincreases north and south of the poles  No deflectioion at the equator

3)3) CoriolisCoriolis FFoorce:rce: - TThehe earearthth rrotateotatess eaeassttwardward

- Deflelectioion causes airir mmotioion to curve to the right inin the N Hem - Deflelectioion causes airir mmotioion to curve to the leftleft iin the S Hem

GeoGeostropstrophichic WindWind –– upperupper levellevel windswinds tthathat mmoveove pparraarralllleell toto isolinesisolines b/b/cc thethe corioliscoriolis forforcece araree eqequalual

. Rather than air fllowinging from higigh to low pressure, airir moves around higigh and llow pressure areas . Occurs witithinin upper lelevelsls of the troposphere

NorthernNorthern HHeemmisispherpheree

NorthernNorthern HemiHemispspheherere

NorthernNorthern HemiHemispspheherere

NorthernNorthern HemiHemispspheherere

NorthernNorthern HemiHemispspheherere

4)4) FFrricicttionalional foforce:rce: dradragg (ba(backwckwaardrd forceforce)) onon wiwindnd asas itit movesmoves overover thethe earearth’sth’s sursurfaceface

. Extends to and elevatioion of about 500m . Decreases witith inincreasining elevatioion . Varies withith surface texture, wiind speed, timeime of day/year, and atmos condititiions → Decreases speed of winind

NorthernNorthern HemiHemispspheherere

SummSummaryary ofof FFoorces:rces: GrGravityavity  pullsls atmosphere toward earth creatiing airir pressure PGFPGF  airir movesmoves from higigh to lolow pressure perpendicular to isisolinlines CoriolisCoriolis  defllects winind dirirectiion due to earth’s rotatiion - zero at the equator - right iin N hem; left inin S Hem FFrrictioniction  backward force on air movement sllowiing itit down

High Pressure Low Pressure

Anticyclone Cyclone NAME

N Hem : cw circulation N Hem : ccw circulation CIRCULATION S Hem : ccw circulation S Hem : cw circulation Air spins out from Air spins in to center SPIN center

VERTICAL Sinking Air Rising Air MOTION Surface divergence Surface convergence HORIZONTAL MOTION Upper-level Upper-level divergence convergence Clear skies, sunshine Clouds, precipitation WEATHER

GGllobobalal AirAir PressPressureure PPaattertternsns::

TTeempermperatuaturere diffdiffereerencesnces alongalong thethe equaequatortor andand atat thethe polespoles causecause prepressuressure differdifferences:ences:

. Pressure dififferences cause air to flolow . Warm airir alalong the equator rises creatiing llow pressure . Coldld, more dense air over the poles sininks creatiing higigh pressure . These pressure differences cause airir tto flolow from the poleles north and south to the equator . Thisis north-south air flolow iis calleled meridinall flow

FFoourur primaprimaryry prpressureessure arareaseas foforr eaeachch hemhemisisppherhere:e:

- EquatoEquatorialrial low-prlow-pressuressuree trtroughough (10(10 NN && S)S) - PolarPolar hhiiggh-prh-pressuressuree cellscells (9(900 NN && SS)) - SubtrSubtropicalopical high-high-prepressuressure ccellellss ((20-20-3535 NN && S)S) - SubpolarSubpolar low-prlow-pressuressuree cellscells ((6060 NN && SS))

- EquatoEquatorialrial low-prlow-pressuressuree trtroughough (10(10 NN && S)S) - Caused by inintense heatining of the earth’s surface - Warm airir risrises creatiing lolow pressure and associatediated weather - Characterized by warm, wet atmospheric conditioions - PolarPolar hhiiggh-prh-pressuressuree cellscells (9(900 NN && SS)) - SubtrSubtropicalopical high-high-prepressuressure ccellellss ((20-20-3535 NN && S)S) - SubpolarSubpolar low-prlow-pressuressuree cellscells ((6060 NN && SS))

- EquatoEquatorialrial low-prlow-pressuressuree trtroughough (10(10 NN && S)S) - PolarPolar hhiiggh-prh-pressuressuree cellscells (9(900 NN && SS)) - Caused by sininkining airir over cold surface - Characterized by cold, dry airir - SubtrSubtropicalopical high-high-prepressuressure ccellellss ((20-20-3535 NN && S)S) - SubpolarSubpolar low-prlow-pressuressuree cellscells ((6060 NN && SS))

- EquatoEquatorialrial low-prlow-pressuressuree trtroughough (10(10 NN && S)S) - PolarPolar hhiiggh-prh-pressuressuree cellscells (9(900 NN && SS)) - SubtrSubtropicalopical high-high-prepressuressure ccellellss ((20-20-3535 NN && S)S) - Caused by dry, sinking airir - Characterized by hot, dry airir - SubpolarSubpolar low-prlow-pressuressuree cellscells ((6060 NN && SS))

- EquatoEquatorialrial low-prlow-pressuressuree trtroughough (10(10 NN && S)S) - PolarPolar hhiiggh-prh-pressuressuree cellscells (9(900 NN && SS)) - SubtrSubtropicalopical high-high-prepressuressure ccellellss ((20-20-3535 NN && S)S) - SubpolarSubpolar low-prlow-pressuressuree cellscells ((6060 NN && SS)) - Caused by the clash of warmer, wet marititiime airir and cold, dry polar airir - The warmer marine airir risises over coldlder, heaviier polar air - Characterized by cool,l, wet airir

EEqquauatoritorialal loloww--presspressureure trotrougugh:h:

 Long, narrow band of lolow pressure encirirclining the earth  Air converges along the surface towards the center . Creates trade wininds (NE iin N Hem; SE in S. Hem) . Air moves toward equator and isis deflected wast by coriolilis  Warm airir rises along equator → Intertropiicall Convergence Zone . Surface flow alonlong the ITCZ isis minimall → Doldldrums

Air Characteristics: - constant altititude and consiistent daylength result iin llarge amounts of availilablele energy - Energy warms and lilightens airir nenear the surface causiing itit to rise - Air isis very moisist; lots of evaporatioion from nearby oceans

EEqquauatoritorialal loloww--presspressureure trotrougugh:h:

 Air rises ininto upper atmosphere moving away from equator . Air sinks and returns to surface and diviverges . Some airir movmoves back toward the ITCZ (hadleley cellll)  Process iis repeated  Results inin band of tropicall wweather systems . Warm, moistist airir massesmasses . Preciipitatiion →Amazon rainforest

SSuubtrobtropipiccalal highigh-prh-presesssuurere ccelellsls::

 Broad zone of higigh pressure alolong subtropicicall llatiitudes  Upper-levell airir moves north and south of ITCZ and eventualllly siinks alolong subtropical lalatituditudes . Moisture is removed by precipitatioion along the ITCZ . Still wiithinin the area of energy surpluses . Resultiing inin anticyclonic conditions characterized by hot, dry airir → world’s’s deserts

Air cirirculalatiion:  Air divergiverges along surface: . Moves toward equator → easterly trade windinds . Moves toward poleles → westerliesies

SSuubtrobtropipiccalal highigh-prh-presesssuurere ccelellsls::

AnticyclonicAnticyclonic circulacirculationtion (c(cww inin NN Hem)Hem) - drier lland condiitioions and cool ocean currents along eastern edge - Wetter land condititiions and warm ocean currents alolong wester edge

- sursurfaceface windswinds alaloongng hhiigghh prpressureessure zoneszones areare calmcalm - Horse latitudes (saililining)

SSuubpbpolarolar loloww-pr-presessuresure ccelellsls::

 Occur along the boundary midlalatititude airir masses and polalar airir . Boundary calleled the polar front . Midlalatiitude air iis warm/cool and moist . Polar air iis coldld anand dry  Air converges along Polar Front and rises . Warmer midlalatiitude air riises above coldelder polar airir . Moisture withiithin warmer air mass is condensed . Results in cyclonic conditions → precipitation . Westerlies and roariing forties

PPoolarlar highigh-ph-presressuresure ccelellsls::

 OccurOccur overover poles,poles, polewarpolewardd ofof thethe ppolarolar ffrontront  AnticyclonicAnticyclonic circulatcirculatiioonn ofof colcoldd,, drdryy airair arouaroundnd popolleses . Weak, polar easterlieies

UUpppeperr AtmoAtmossphpheriericc CCirircculaulatiotionn

Upper llevell atmospheric circirculatiolation is monitoreitored on a constant pressure surface or a constant iisobaric surface

The height of the 500mb pressure surface: - Thisis heighight varies - The layer of airir under an upper-levell highigh pressure system are thicicker - 500mb isobar isis at a higigher elelevatiion - 500mb isobars bend poleleward on map → ridge

- The layer of airir under an upper-levell lowlow pressure system are thininner - 500mb isobar isis at a higigher elelevatiion - 500mb isobars bend equatorward on map → trough

Upper atmospheric ciirculation generate surface pressure systems

 DivergeDivergencence ofof upperupper-leve-levell aairir rresultsesults inin aa voidvoid . Surface airir wililll rise to fililll upper lelevel voidid . Riising airir at the surface results inin surface lolow pressure cyclones

 ConverConvergencegence ofof uupperpper-level-level airair resuresullttss inin buildbuild uupp ofof airair . Air wililll be pushed down toward the surface . Sinkining air at the surface resultslts iin surface high pressure antiicyclolones

RossbyRossby WavWaves-es- uundulationndulationss wiwitthihinn thethe smosmoootthh westewesterlyrly flowflow ofof geostrgeostrophicophic windswinds . Coldld airir poleleward of polarlar front; warm airir eqequatorward . Develolop along the polar jjet stream . Waves send coldld polalar airir equatorward and warm midlalatititude aiir poleward . Diistiinct cyclolonic and antiicyclolonic systems form as warm airir isis pushed cloloser to the poles and coldld airir iis squeezed toward equator . Coldld, cyclonicic systems can be squeezed out and move even further south

Jet Stream: irrirregular, concentrated band of windind at severall llocatioions that supports surface weather systems . 160-480 km widide, 900-2150 m thick, withith core velolocititiies exceeding 300 kmph . Weaken during summer and strengthen iin wininter

Polalar jetjet stream - located along the tropopause along the polalar front  Elevation of 7600-10,700m, between 30-70 N and S Subtropicall jjet stream - along the boundary btw tropicical and midlalatititiide airir  20-50 N and S

The polar and subtropicall jjet streams can flow over N. America at the same tiime and can even merge

LoLoccalal WWiindsnds

AA SeaSea BrBreeeezeze

SeaSea bbreezereeze -- durining the day the laland heats faster than the ocean . Air over the laland iis warmer than that over ocean . Warmer airir isis leless dense and rises lleaviing a voiid over land . Cooler ocean airir fflolows lalaterallyly over lland to fililll void

 AA seasea bbreezereeze isis strostrongestngest iinn mid-mid-afterafternoonnoon!! Why?…..Why?…..

AA LandLand BreeBreezeze

LaLandnd BreezeBreeze:: atat nightnight lanlandd coolscools ffasteraster thanthan oceanocean . Air over lland iis cooleler than that over ocean . Warmer, lless dense air over ocean rises leaving a voidid . Cooler air over lland flolow llateralllly over ocean

Mountain-in-valllley breezes - breezes created by the exchange of cool mountain air and warmer valllley airir . Valllley air gains heat rapiidly durining the day  Warmer valleyley airir riserises movinging upslope . Mountain air loloses heat rapididlyly at nigight  Cooler mountainin aairir ssiinks downslope

Katabatiic wininds - coldld dense air from elelevated terrain flows downslolope . Larger regionall scale than mountain vallelley breezes . Generallyly form alolong an elevated highland or pllateau  Also very common over icice sheets

Monsoonal Winds - shififting winind system seasonally b/c of regioional scalele pressure changes . Typicical of SE Asia but alslso occurs over SW U.S. . Large seasonal temp diffifference occur over SE Asiia b/c of iits contininentallitity . In wiinter, ITCZ isis over Indiaian Ocean and Asiaia dominated by subtropical high pressure celll  Region characterised by dry, cool airir witith very little precip

Monsoonal Winds - shififting winind system seasonally b/c of regioional scalele pressure changes . Typicical of SE Asia but alslso occurs over SW U.S. . Large seasonal temp diffifference occur over SE Asiia b/c of iits contininentallitity . In wiinter, ITCZ isis over Indiaian Ocean and Asiaia dominated by subtropical high pressure celll  Region characterised by dry, cool airir witith very little precip . In summer, ITCZ is over SE Asiaia, whicich isis dominated by tropicical lolow pressure, and subtropicicall higigh pressure isis centered over Indianian Ocean  Results in world record rainfall amounts

OOceancean CCiircrcululatiationon

OceOceanan curcurrenrentsts araree drivedrivenn byby ththee frfricicttiioonalnal drdragag ooff windwind andand thetheiirr diredirectionction isis afaffectedfected by:by: - the coriolisis force - Water densityity diffifferences caused by temperature and salinlinityity - Confiiguratiion of laland masses and the ocean flloor - Astronomicall forces (tiides)

SurfSurfaceace CurCurrentsrents –– oceoceanan curcurrentrentss areare drdriivenven byby tthehe circulatcirculatiioonn aroaroundund highhigh prpressuressuree systemsystemss andand deflectdeflecteded byby thethe corioliscoriolis foforce.rce.

. Gyres: circulatiion patterns caused by circirculalatioion around higigh pressure systems

EquatEquatorialorial CurCurrentsrents –– oceoceanan curcurrentrentss thathatt areare drdriivenven westwarwestwardd byby ththee trtradeade wwindsinds

. Located near the equator . Are not defllected by coriolislis force b/c itit is zero alolong the equator . Such currents push water west toward the eastern shores of lland masses . Causes water to pilele up alolong eastern coasts of contiinents Western Intensification (15cm)

TThhee casecase ofof tthehe rurubberbber duck!duck! - Jan 1994, a lalarge container shipip from Hong Kong - Loaded withith toys and other goods - One container splitlit off Japanese coast (30,000 rubber ducks, turtlles and frogs) - Simiilalar thining happened withith 60,000 pairsirs of athleletiic shoes - Tripip of the floatiing ducks took over a decade!

DeepDeep WWaaterter CiCirrculationculation –– oceanocean waterwater alsoalso mmovesoves alonalongg thethe oceaoceann floorfloor inin distinctdistinct pattpatternserns resultingresulting frofromm ververticaltical momotiontion

Upwellilling currents: occur where surface water iis swept away from the coast by surface divergence (coriollisis and offshore wiinds) . this allolows cold,ld, dedeep ocean water to move up from the ocean floor toward the surface → nutrients for fishinging

Downwellilling currents: occur where excess water accumulalatioion along a coast causes surface water to be pushed to greater ocean depths (west end of the equatorial currents) . Thisis alallolows surface ocean water to move down to the ocean floor . Warmer surface water iis cooled . Water fllows along the ocean floor untiill itit iis upwellelled

This continuous flolow of surface water to the bottom and bottom water to the surface transports heat and energy around the glolobe:

- Water that moves along the equator is warmed and transports that heat to the poleles where it loses heat as it cools, sinks, and fllows back to the ocean floor - That coldld bottom water eventualllly upwelllls and is warmed and continues circulatiing - Process takes about 1,000 years - Currents have shifted throughout geologic historyistory