geography & climate - university of british...

Geography&Climate

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Allspecieshavelimitstotheirdistribu9ons…Toexaminespeciesranges,ithelpstounderstandthephysicaltemplateandclimateThisisfundamentaltobiogeography

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Allbiogeographicpa@ernsareul9matelyinfluencedbythegeographictemplate

Environmentalcondi9onsvaryinahighlynon-randommanneracrossgeographicgradients(e.g.,la9tude,eleva9on,depth,proximitytomajorlandforms–mountains,coastlines)Mostbiogeographicpa@ernsarederivedfromthisveryregularspa9alvaria9oninenvironmentalcondi9ons

Allbiogeographicpa@ernsareul9matelyinfluencedbythegeographictemplate

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(5)Some9mescalledTECOevents–plateTectonics,Eusta9cchangesinsealevel,Climatechange,Orogeny(mountainbuilding)

Figure3.1Lomolinoetal.2010

Climatereflectstemperatureandprecipita9on

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Climateandtectonicchangearethemostimportantlarge-scalefactorsinfluencingspeciesgeneraldistribu9onsHerewe’lllookathowtemperatureandprecipita9onvaryacrossgeographicandregionalscales

FromLomolinoetal.2010

Temperatureandthermalenergy

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Sphericalshapeofearthcausesla9tudinalgradientinthermalradia9on


AngleofincomingradiantenergyaffectsamountofheatabsorbedMostintensehea9ngoccurswhereincomingsunlightisperpendiculartoEarth’ssurface:1) Thegreatestamountofenergyisdeliveredtothesmallestsurfacearea(a<a’)

2) Solarradia9onpassesthroughlessatmosphere;thedistancetraveledthroughtheairisminimized(b<b’)


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Theangleofinclina9onoftheearth’saxiscausesseasonalitySolarradia7onfallsperpendicularlyondifferentpartsoftheEarthatdifferent7mesofyear



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Lookingatthefigureontheright,whatdayoftheyearisit?

Theangleofinclina9onoftheearth’saxiscausesseasonalityWhatistheangleandhowdoesthisrelatetotheTropicofCancerandCapricorn?

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Coolingeffectsofeleva9on

Weexaminedla9tudinalvaria9onintemperatureandseasonality...whataboutal9tude?WhydoesMountKilamanjaro,neartheequatorinEastAfrica,havepermanenticeatthetop?Thishastodowiththermalproper9esofair...

Asaclimbergoesupamountainside,thelength(andpressure)ofthecolumnofairabovetheclimberdecreasesWithreducedpressure,airundergoesadiaba%ccooling,aprocesswheregasesloseheatenergyasmoleculesmovefartherapart(andhavefewercollisions)

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columnofairinto

atmosphere

Lowerpressure

Higherpressure

Coolingeffectsofeleva9on

h@p://www.cslctx.org/2012/02/17/the-view-from-the-top/

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WindsandCurrents

h@p://video.mit.edu/watch/the-coriolis-effect-4407/

CoriolisEffect:thetendencyformovingobjects(e.g.,windandcurrents)toveerclockwise(totheright)intheNHandcounterclockwise(totheled)intheSH.Weseethiseffectgenerallybetween0°and30°NorthandSouthla9tude

WindsandCurrents

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Differen9alhea9ngwithla9tudedrivesthemajoratmosphericaircircula9on,resul9nginglobalwindpa@erns


1)  Equatorisheatedmostintensively.Airattheequatorexpandsasitisheated,becomeslessdensethansurroundingairandrises

2)  Risingairreducesatmosphericpressureovertheequatorandsurfaceairnorthandsouthofequatorflowsintoareaofreducedpressure

3)  Risingheatedairundergoesadiaba9ccooling,ispushedawayfromtheequator,anddescendsat~30degreesNandSla9tude

WindsandCurrents

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4)  Circula9ngairmassesproducesurfacewindsblowingtowardtheequatorbetween0and30degreesandtowardthepolesbetween30and60degrees

5)  SurfacewindsdonotblowdueNorSbecauseoftherota9onoftheEarth



WindsandCurrents

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6)  EverypointonEarth’ssurfacemakesonerota9onevery24hours.

7)  Pointsathigherla9tudestravelashorterdistancewitheveryrota9on,movingataslowerratethanpointsattheequator

8)  ThisinducestheCorioliseffect,wheresurfacewindsaredeflectedtowardtherightintheNHandtotheledintheSH



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WindsandCurrentsCoriolisEffect:thetendencyformovingobjects(e.g.,windandcurrents)toveerclockwise(totheright)intheNHandcounterclockwise(totheled)intheSH.Weseethiseffectgenerallybetween0°and30°NorthandSouthla9tude

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WindsandCurrentsSurfacewindsini9atethemajoroceancurrents(1)  Tradewindspushoceancurrentswestwardattheequator(2)  Westerliesproduceeastwardcurrentsathighla9tudes(NandS)Thenetresultsarecircularoceancurrents,clockwiseintheNHandcounter-clockwiseintheSH.

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WindsandCurrentsThefivemajoroceancirclingcurrentsarecalledgyres:N.Atlan9c,S.Atlan9c,N.Pacific,S.PacificandIndianOceanGyres.

WindsandCurrents

17Figure3.5Lomolinoetal.2010

Thetemperatureofcurrentsandsurfacewindsaffectstheclimateonland

Geographicprecipita9onpa@erns

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Globaltemperature,winds,andcurrentsinteracttoinfluenceprecipita9on

(FromLomolinoetal.2010)

Partofthishastodowithcloudforma9onandadiaba9ccooling...Asairwarms,itcanabsorbmorewatervaporevaporatedfromlandandwaterWhenaircontainsmoistureandcools,thereisapointatwhichtheairissaturatedwithwatervapor(dewpoint)Furthercoolingresultsincondensa9onandcloudforma9on.Whenwaterandicepar9clesaretooheavytoremainairborne,theyfallasrainandsnow.


Geographicprecipita9onpa@erns

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Tropical rains are heaviest when thesunisdirectlyoverheadandtherateofhea9ngismostintense(thespringandfallequinoxes)

Horse La%tudes: warm, dry surface winds"dry-out" the land and create most of ourgreatdesertsnear30oNandSla9tude(e.g., Mojave, Sonoran, Sahara, Gobi, andGreatSandydeserts)


HorseLa9tudesandadjacentzones

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TwobeltsofdryclimatesencircletheglobeOverland,thesebeltsaretheworld’sdesertsandMediterraneanclimates(mildrainywintersandhotdrysummers)Overoceans,thesebeltshavehotairandli@lewindThetermmaycomefromwhenSpanishshipstransportedhorsestotheWestIndies

h@p://www.rossway.net/horselat.htm

Shipswouldslowinmid-oceaninthisla9tude,prolongingthevoyage...watershortagesforcedcrewstothrowtheirhorsesoverboard

HorseLa9tudesandadjacentzones

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DesertsandMediterraneanclimatesareusuallyontheWesternsideofcon9nentsHere,thelandtemperatureiswarmerthanthecoldocean…coolwesterlywindsofftheoceanwarmwhentheypassoverlandThus,theyabsorblotsofwaterand“drytheland”whentheycomeonshore

Horsela9tudes

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HorseLa9tudesandadjacentzonesTheworld’sdriestdesertsoccurwherewesterliesbringcoldcurrentsandsurfacewinds.Inwinter,thereisli@lerainfallandsummersarehotanddryAtacamaDesert:1mm/year NamibDesert:2-20mm/year

Regionalprecipita9on

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Mountains,inpar9cular,havecomplexeffectsonregionalprecipita9on



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Theadiaba%clapserateishowquicklyaircoolsasitrises.Thisratevariesforseveralreasons,butgenerallydifferswithandwithoutcondensa9on.



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AircoolsandlosesmoistureasitmovesupthemountainslopeAsitpassesoverthecrestanddescends,itwarmsatahigherrateThiscreatesarainshadoweffectontheleewardsideofmountains

Rainshadoweffect(e.g.,tropicalislandofPuertoRico) Figure3.7Lomolinoetal.2010

Butit’scomplicated...

Mountainsdifferintemperatureandprecipita9onregimesformanyreasons:la9tude,heightandage,tonameafewAsacomparison…considerthesetworanges…

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Whistler,PacificRange,Bri9shColumbia,Canada

GreatSmokyMountains,AppalachianRange,Tennessee-NorthCarolina,USA

Whistlervs.GreatSmokyMountains

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La9tude:51degreesNHighestpeak:4019m(13186d)

Age:60millionyears

La9tude:40degreesNHighestpeak:2037m(6684d)

Age:480millionyears



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Whistlervs.GreatSmokyMountains

Thesemountainshavedifferenteffectsonregionalprecipita9onandclimate:oldermountainstendtobesmallerwithsmallerrainshadoweffects.

Climatevaria9on

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ElNinoSouthernOscilla%on(ENSO):periodofweatherchangethatoccursevery2-7yearsduetostrengtheningoftheequatorialcountercurrent(causes9llunderstudy).Increasedrain(oden10x)inaridcoastalregionsofSAwithreducedcoastalupwelling

Seasonalandlong-termvaria9oninprecipita9onare9edtochangesinsolarradia9onandcurrentstrength

Climatevaria9on

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AtacamaDesert

Seasonalandlong-termvaria9oninprecipita9onare9edtochangesinsolarradia9onandcurrentstrengthElNinoSouthernOscilla%on(ENSO):periodofweatherchangethatoccursevery2-7years

duetostrengtheningoftheequatorialcountercurrent(causes9llunderstudy).Increasedrain(oden10x)inaridcoastalregionsofSAwithreducedcoastalupwelling

StrongwarmcurrentpushesmoistureladenairupthecoastsofNandSAmericaResultsinheavyprecipita9oninwinterwhenthelandiscolderthanoffshorewatersTheonly9meitrainsintheextremelyaridcoastaldesertsofSouthAmerica

Climatevaria9on

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GalapagosIslands

Seasonalandlong-termvaria9oninprecipita9onare9edtochangesinsolarradia9onandcurrentstrengthElNinoSouthernOscilla%on(ENSO):periodofweatherchangethatoccursevery2-7years

duetostrengtheningoftheequatorialcountercurrent(causes9llunderstudy).Increasedrain(oden10x)inaridcoastalregionsofSAwithreducedcoastalupwelling

Bringsmorerain(goodforlanddwellers)Warmcurrentreducesupwellingandfood(badformarinelife)

Climatevaria9on

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Seasonalandlong-termvaria9oninprecipita9onare9edtochangesinsolarradia9onandcurrentstrength

TheespeciallystrongElNinoin1983increasedfoodavailabilityontheislands,whichalleviatedselec9ononbeakandbodysizeintwofinchspecies

ElNinoSouthernOscilla%on(ENSO):periodofweatherchangethatoccursevery2-7yearsduetostrengtheningoftheequatorialcountercurrent(causes9llunderstudy).Increasedrain(oden10x)inaridcoastalregionsofSAwithreducedcoastalupwelling

Climatechange

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Globalclimatehaschangedfrequently.Climatehasclearlychangedwithcyclesofglacia9on(moreonthislater)

(FromGates1993)

Changesincelastglacialmaxhasnotexceededabout1oCper1000yrs.

34(FromLomolinoetal.2010)

Climatereflectstemperatureandprecipita9on

Thismapshouldbemorefamiliarnow,withanunderstandingofla9tudinalvaria9onintemperatureandwhywehavedesertsandrainforestsatdifferentla9tudes…butalsowhythisoversimplifiesEarth’sclimateandclimatevaria9on.

ClimateandClimateChangeReferencesforthissec%on:Gates,D.M.1993.ClimateChangeanditsBiologicalConsequences.Sunderland,MA:SinauerAssoc.Grant,P.R.,andB.R.Grant.2002.Unpredictableevolu9onina30-yearstudyofDarwin’sfinches.Science296:707-711.Lomolino,M.V.,B.R.Riddle,R.J.Whi@aker,&J.A.Brown.2010.Biogeography(4thed.,Chapter2).SinauerAssociates,Inc.,Sunderland,Mass.TheCorioliseffectandthedirec9ontoiletsdraininNorthern&SouthernHemispheres:h@ps://www.youtube.com/watch?v=rdGtcZSFRLk

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