Power to the Looney-toons!i. The Earth heat budgetii. Wind PatternsOCNG 251: OceanographyOCNG 251: OceanographyTuesday, Sept. 30Tuesday, Sept. 30thth, 2008, 2008Part 1Part 1Oceans and Climate SystemsOceans and Climate SystemsWhat do we have left before Mid-Term?1)1)The structure of the OceansThe structure of the Oceansa)a)The Earth heat budgetThe Earth heat budgetb)b)Wind patternsWind patterns2)2)Filling up the OceanFilling up the Oceana)a)Physical Properties of WaterPhysical Properties of Waterb)b)TS Diagram TS Diagram -- Density Structure of Oceans Density Structure of Oceans3)3)The Ocean in motionThe Ocean in motiona)a)Horizontal and vertical circulationHorizontal and vertical circulationb)b)Global circulationGlobal circulation4)4)Climate VariabilityClimate Variabilitya)a)Climate Change: Past & FutureClimate Change: Past & Futureb)b)El El Niño-Southern Niño-Southern & North Atlantic Oscillations& North Atlantic OscillationsRadiation and temperatureRadiation and temperatureAny object with a temperature above absolute Any object with a temperature above absolute ““00””1)1)Emits radiation!Emits radiation!2)2)At a wavelength At a wavelength directlydirectly proportional to its proportional to itstemperature (the higher the temperature, thetemperature (the higher the temperature, thefaster the electrons vibrate)faster the electrons vibrate)Stefan-BoltzmannStefan-Boltzmann LawLawE = E = !!TT44E is the maximum emitted energy per mE is the maximum emitted energy per m22! ! is a constant (5.67x10is a constant (5.67x10-8-8 W/m W/m22.k.k44))T is the objectT is the object’’s surface temperature (in °Kelvin)s surface temperature (in °Kelvin)RadiationRadiationThe basics about electromagnetic radiationThe basics about electromagnetic radiationThe shorter the wavelength The shorter the wavelength !! the more energy it carries the more energy it carries(from X-rays and Gamma rays to radio waves)(from X-rays and Gamma rays to radio waves)E = E = hhƒƒ or or hc/hc/""!! EE is the energy of a photon is the energy of a photon!! ƒƒ is the frequency of the is the frequency of thecorresponding electromagneticcorresponding electromagneticwavewave!! "" is its wavelength is its wavelength!! hh is a constant known as is a constant known asPlanckPlanck’’s constant (6.63 10s constant (6.63 10-34-34Joules per second).Joules per second).EarthEarth’’s s Radiative Radiative equilibrium temperatureequilibrium temperatureThe state at which absorption of solarThe state at which absorption of solarradiation = emission of IR radiation:radiation = emission of IR radiation:255 255 °°K = -18K = -18°°CCBut the actual T° ofBut the actual T° ofEarth is much higherEarth is much higherthan thatthan that288 288 °°K = +15K = +15°°CCHow can we explain theHow can we explain the+33+33°° difference? difference?Any object with a temperature above absolute Any object with a temperature above absolute ““00””3)3)Emits radiation at a wavelength inverselyEmits radiation at a wavelength inverselyproportional to its temperature (the higher theproportional to its temperature (the higher theenergy, the shorter the wavelength)energy, the shorter the wavelength)WienWien’’s s LawLaw""maxmax = Constant/T= Constant/T""maxmax is the maximum wavelength emittedis the maximum wavelength emittedThe constant is ~3000 The constant is ~3000 µµm Km KRadiation and temperatureRadiation and temperatureRadiation Spectra of Sun and EarthRadiation Spectra of Sun and Earth""maxmax Sun = 3000 Sun = 3000 µµmK/6000 K = 0.5 mK/6000 K = 0.5 µµmm""maxmax Earth = 3000 Earth = 3000 µµmK/300 K = 10 mK/300 K = 10 µµmm••44% of the sun44% of the sun’’s radiation in the s radiation in the visible regionvisible region (0.4-0.7 (0.4-0.7 µµm)m)••7% as UV and 37% as near IR7% as UV and 37% as near IR••88% of the sun energy is radiated at wavelength <1.588% of the sun energy is radiated at wavelength <1.5µµmm••While the Earth emits in the While the Earth emits in the far IRfar IR: 10 : 10 µµmmFate of RadiationFate of RadiationDependent on the medium it is meetingDependent on the medium it is meetingRadiation absorption and emissionRadiation absorption and emissionRadiation may be absorbed by many types ofRadiation may be absorbed by many types ofmaterials. It turns out that all objects are able tomaterials. It turns out that all objects are able toemit radiation at all wavelengths and similarlyemit radiation at all wavelengths and similarlyabsorb all types of radiation.absorb all types of radiation.The energy is not lost but rather converted to someThe energy is not lost but rather converted to sometype of internal energy within the absorbing mediumtype of internal energy within the absorbing mediumAny object that is a perfect absorber and perfectAny object that is a perfect absorber and perfectemitter is called a emitter is called a blackbodyblackbodyThe Sun and Earth both absorb and emit radiationThe Sun and Earth both absorb and emit radiationclose to ~100% efficiency close to ~100% efficiency !! blackbodiesblackbodiesRadiation absorption and emissionRadiation absorption and emissionSo the sun So the sun ““shinesshines”” and the Earth and the Earth ““bakesbakes””but reallybut really…… The Earth also The Earth also ““looseslooses”” its energy as fast its energy as fastas it gains it (so it as it gains it (so it ““shinesshines”” in its own right) in its own right)Radiating in the IR portion of the spectrumRadiating in the IR portion of the spectrum!! Long wavelength, low radiation energy Long wavelength, low radiation energyRadiation absorption and emissionRadiation absorption and emissionNot all substances on Earth behave as Not all substances on Earth behave as blackbodiesblackbodiesMost substances are selective absorbers (i.e. glassMost substances are selective absorbers (i.e. glass!! UV and IR) UV and IR)Objects that selectively absorb radiation alsoObjects that selectively absorb radiation alsoselectively re-emit radiation at the sameselectively re-emit radiation at the samewavelength: wavelength: KirchhoffKirchhoff’’s s LawLawGood absorbers are good emitters at a particular Good absorbers are good emitters at a particular !!Specifically for gasesSpecifically for gases!!Selective absorption of radiation in theSelective absorption of radiation in theAtmosphereAtmosphereOO22 and O and O33 absorb almost 100% of the UV radiation