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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 1°C 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 -20°C in to steam? Heat Fluxes o Heat is transferred in and out of the ocean's surface o Flux= Δ quantity/area*time = J/m²*s = W/m² • 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/m²) = cT ⁴ c = 5.67*10ˉ W/m²°K ⁸ T must always be in Kelvins • The radiation has a range of wavelengths but there is a wavelength of max. emission Wein's Law: λ ( μ m) = 2897.8 μ m/T (°K) •...
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This note was uploaded on 04/13/2008 for the course MSCI 304 taught by Professor Gilman during the Spring '08 term at Coastal Carolina University.
- Spring '08