TempTemperatueraturree WhatWhat iiss temtemperaperature?ture? Heat – form of energy that flows from one system or object to another b/c they have different temperatures Temperature – a measure of the average kinetic energy of individual molecules . We feel the effect of temperature as sensible heat transfer from warmer to cooler objects Temperature and Heat are relalated b/c changes inin temperature occur by absorption or emissioion (gainin/loloss) of heat energy SSuurfarfaccee TTememperperaturaturee During the day, SW iinputs usuallylly exceeds LW outputs and heatiing of the surface occurs Latent and sensibiblele heat are also iimportant in determinining surface temperature (e.g. desert vs. oasis) TTememperperatureature SSccalesales KelvinKelvin (K)(K) == absabsoluteolute ttemperemperatuaturere scale,scale, -2-273.1573.15 degrdegreesees CelsiCelsiuuss oror 00 dedegreegree KK CelsiusCelsius (C)(C) == interninternationalational sstandartandardd FFaahrehrenheitnheit ((FF)) == uusedsed inin tthehe USUS MeMeasurinasuringg TemTemperperatuaturere TThhermermomeometerter –– anan instinstrumrumentent uusedsed toto meameasuresure temtemperatperatureure . Alcohol thermometer: alcohol has a freeziing point -112 C so itit is used for cold weather measurements . Mercury thermometer – mercury has a freezining poinint of -39 C so itit isis better suited for lless extreme environments TThhermermomeometersters measumeasurere tetempmp bbasedased oonn ththee thethermalrmal prproperopertiesties ofof thethe liquidsliquids aabove:bove: - Fluids expand when heated, contract when cooleled - The rise and fallll ofof the fluidid isis measured usining calilibratiions marked on the tube MeMeasurinasuringg TemTemperperatuaturere Standard Temperature Measurement: - Taken outdoors - Thermometer is placed wiithinin aa thermometer shelterlter - A white (for albedo) box with vents (for air flow) that shades the thermometer from direct sunlight - Temperatures taken at a standard height of 1.2m above the ground DiffDiffereerentnt TemTemperperatuaturere MeaMeassururememenentsts:: Max temperature – higighest temp readining Min temperature – llowest temp readining Dailily mean temperature – average of the max and min dailyly temp Monthlyly mean temperature – average of dailyly mean temps Annuall temperature range – dififference between the llowest and higighest monthlyly mean temperatures for a year AirAir vsvs SurSurfaceface TTempemperateratureure Air temperature iis measured a short disistance (usualllly 1.2m or 4ft) above the surface Air temperature can be quite diifferent than surface temperature However, airir temperature tends to mirror surface temperature EartEarth’sh’s temptemperateratureure pattpatternserns iinnflfluuencedenced byby foufourr pphysichysicaall prproperoperties:ties: 1) LatLatiittudeude 2) ElEleevationvation 3) CloudCloud CCoveoverr 4) LanLandd vs.vs. ooceancean WhatWhat factorfactorss contcontrolrol tetempermperatuature?re? 1)1) LatitLatitudeude LaLatitittudeude Latiitude controlsls: 1) Dayllength 2) Anglele of incidence Insolation is the siinglele most important inflluence on temperature variatiions Why don’t world temperature patterns follolow llatiitudinall bands? LaLatitudetitude andand aiairr tetempermperaturaturee Seasonal range inin airir temperature iis strongly dependent on lalatiitude – inincreases as you get closeloser to the polesles . More direct rays of sunliglight during summer . Longer daylelength inin summer; shorter in wiinter Equatorial lolocations may actualllly be warmer during an equinox than during a solstice! Generallyly, airir temperature lalags behind solalar radiatioiation by one month over laland and by two months over water 2)2) AAltitudltitude/Ele/Eleevationvation WhatWhat isis thethe imimpactpact ofof elevatelevatiioonn onon temtemperaperaturture?e? ElEleevation:vation: temtemperaperatureture decrdecreaseseases withwith iinnccrreasingeasing elevationelevation withinwithin ththee trtropospopospherehere At siimilar llatitudes, mountainous areas experience lower air temperatures than llocatioions near sea lelevel Remember that densitity alslso decreases withith iincreasiing altltiitude: . As the atmos thinins, the no. of airir molemolecules decrease . Fewer moleculesles inin the air means less energy absorption . Less SW radiatioiation is reflected and scattered into space . Surface gains and looses energy more rapidly under lower atmospheric pressure 3)3) ClClooudud CoveCoverr CloudCloud CCoover-ver- cloudsclouds areare tthehe mmostost vavariableriable ffactoractor influencinginfluencing thethe EEaarth’srth’s EBEB Cover approximatelimately 50% of the earth and theirir efeffect on temperature depends on their type, heigight and density Moderate temperature → decreasinging daytiime temps and iincreasing nigighttime temps Cllouds absorb and reflelect SW energy during the day → cooliling effect Cllouds absorb and reradiate LW energy at nigight → warming effect 4)4) LandLand vs.vs. OceOceanan LanLandd andand WaterWater ContraContrastssts - Land has dififferent thermall propertiies than water resultltiing inin dififferences inin temperature - Land and water absorb and store energy dififferentlyly b/c of the physicicall nature of laland and water Four main differences: 5) Evaporation 6) Transparency 7) Speciificic Heat 8) Movement LaLandnd-W-Waaterter CCoontrantrasststs 1)1) evapevaporatoratiioonn:: More energy at the ocean surface goes ininto evaporation than on land 84% of allll evaporation on earth occurs over the ocean Evaporatiion is a cooliling process Results in llower temperatures over oceans than on land 22)) trtranspaansparencyrency:: Lighight can be transmitted through water but not through lland Lighight strikiniking land does not penetrate but is absorbed → heat surface Energy transmits through water to a depth of approx. 60m Energy has a greater distribistribution wiithinin water than on land LaLandnd-W-Waaterter CCoontrantrasststs 3)3) SpecificSpecific heaheatt:: Heat capacity of a substance When equal volumes of land and water are compared, water requiresires more energy to increase iits temperature than lland Water can holdld more heat than soilil (specific heat iis x4) Land heats and cools quick, water heats and coolsls slowslow 44)) mmovemeovementnt:: Land iis solidlid and does not move whereas water is flluid and capablele of movement Mixinging between warm and coldld llayers iis possible withiithin water and not possiblele wwithiithin land Mixinging spreads availalable energy over and even greater volume WhatWhat iiss thethe iimmpactpact oonn dadaiilyly ttemperemperaturatures?es? LESSLESS DIURNADIURNALL TTEMPEEMPERATRATUREURE CHANCHANGGEE!! Marinine llocatioions have cooler days and warmer nigights than comparablele ininlaland llocatioions Marinine effect (maritime)ime) – lolocatiions that exhibibitit the moderating iinfluences of the ocean. Smallller range between max and min dailyly and annuall temps. Contininentall Effect (contininentallitity) – areas that are lless affected by the sea. Greater range between max and min dailily and annual temp. DiDiuurnalrnal (Dail(Dailyy)) CycleCycle ofof AAirir TTememperperaattureure Generallyly folllolows the sun; however, itit llags due to the delalay inin heatining the atmosphere Coldldest airir temperature usuallyly occurs jusjust after sunrise – no solar radiiatiion during nigight Warmest airir temperature occurs about 3pm when turbulenlent miixing beginins (warm bubbles of airir rise and are replalaced by colder airir from aloft) EEndnd ofof mmataterialerial ccontaontaiinedned inin tthehe MiMidtdtermerm!! DiDiuurnalrnal (Dail(Dailyy)) CycleCycle ofof AAirir TTememperperaattureure An invinversion may occur inin the mornining hours since the earth’s surface cools rapidlidly when the sun sets GlobGlobalal temtempeperatratureure papattertternsns TTeempermperatuaturere papattertternsns rresultesult frfrom:om: - LatLatiittudeude - ElEleevationvation aabovebove seseaa levellevel - CloudCloud cocoverver - LanLand-ocead-oceann heheatingating ddiiffffereerencesnces Maximuimum monthlyly mean temperature occurs inin Julyly (N. Hem) . Lag after summer solstiice b/c iinputs are stilll lalarger than outputs shortlly after max insolation . Similailar to lag in dailily air temperature Minimuimum monthlyly mean temperature occurs inin January (N. Hem) . Lag after winterinter solsolstiice b/c iinputs are stililll smalsmallerler than outputs shortlly after min iinsolatiolation . Similailar to lag in dailily air temperature HHoorizrizoontantall TempTempereraturaturee PattePattern:rn: IsotIsotherhermsms –– lineslines ofof eequalqual tetempermperaturaturee . Trend east and west . Deviiate from trends due to mountainins and laland-ocean contrasts TThhermermalal EEqquatouatorr –– isoisothermtherm connconnectingecting ppoointsints ofof highesthighest temtemperaperaturturee . Hovers around latititudininal equator . Shififts north inin summer (accordining to lolocatiion of max iinsolalatioion) . Shififts south iin wininter JanuJanuaryary temptemperatueraturere pattepatterns:rns: . Temp decreases north and south of the thermal equator . Isotherms bend south over laland Cooler temps are found south over lland than over water Land lolooses heat more quickly than water . Lowest temp over Siberiaia (contiinental lolocation) . Isotherms move further south over mountaiinous regioions (elevation effect) JulyJuly ttempeemperaturraturee ppatteratterns:ns: . Temperature stiillll decreases north and south of thermal equator . Lower temperature