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Unformatted text preview: Heat An easy way to convert from metric to English: Volume: 1 L 1.1 qt. Speed: 1 m/s 2.2 mph Mass: 1 kg 2.2 lbs Length: 1 m 3.3 ft. Heat: o Units: calorie or joule 1 calorie=4.18 joules o The amount of total kinetic energy Vs. temperature: the average kinetic energy o Both pots boil at the same temperature but the large pot requires more heat since it has many more molecules Specific Heats: o Water has the largest specific heat of any substance on Earth o The amount of heat needed to raise 1g of substance by 1C Heat Capacity o How much heat a substance can absorb before its temperature changes Latent Heat o If you add heat to water or air, 3 properties change: Temperature Volume Phase o Is the heat that goes into changing a substance's phase o For water: it takes 540 calories/g to change to a gas o How much heat would it take to change 2g of ice at -20C in to steam? Heat Fluxes o Heat is transferred in and out of the ocean's surface o Flux= quantity/area*time = J/m*s = W/m 1 W=1J/s o Heat is added: Solar radiation (Qs)- short wave radiation or insolation This is the largest and only input considered o Heat is lost: Back radiation (Qb)- long wave radiation Evaporation (Qe)-latent heat flux Sensible heat flux (Qh)- cools by contact with cold air Currents (Qv)-advective heat flux o Globally, over the long term (1 year or more): Heat in = Heat out Qt=heat entering-heat leaving = 0 Qt dt = 0 Qt = Qs - Qb - Qe - Qh - Qv Advective heat flux (Qv) is not an in or an out for the oceans as a whole but works to pump heat in or out of an area to maintain the balance If this didn't happen, the tropics would come to a boil and N and S of 30 would freeze over o For short term periods: Why do the oceans circulate? o The earth wants an even distribution of heat o The oceans must circulate to maintain the balance in a global perspective Unequal heating and cooling: The tropics are constantly gaining heat The poles are constantly losing heat Produces wind driven circulation (surface) Goal: heat is pumped poleward Produces thermohaline circulation (deep) Goal: cold water is pumped equatorward Surface Heat Fluxes Physics Review: o Electro-magnetic spectrum The shorter the wavelength, the more dangerous o Everything with a temperature gives off radiation Amount: Q (W/m) = cT c = 5.67*10 W/mK T must always be in Kelvins The radiation has a range of wavelengths but there is a wavelength of max. emission Wein's Law: ( m) = 2897.8 m/T (K)...
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- Spring '08