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Originally Posted by Long Haired Git
No links. But the energy that was heat of the liquid water and heat of the air has gone into evaporation (phase change) of the liquid. The latent-heat-of-evaporation is massive compared to the energy changing water's temperature.
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Ah, thank you! Latent Heat of Evaporation did the trick for me on Google. I vaguely remember it from middle school 30 or so years ago as it related to distilling. You know, heat the mixture to the boiling point of the component you are trying to extract, and as long as the temperature holds at that point capture the vapors. The temperature holds steady because the applied heat is going to the phase change.
Apparently these days the vogue term is Specific Latent Heat of Vaporization. There were also some interesting tidbits I followed from the commercial HVAC perspective, and USA Today of all places had an interesting article about weather.
The bottom line is the heat energy to change water state from liquid to gas is very high compared to the amount required to change the temperature of liquid water, so a little evaporation can result in a lot of cooling.
I'm old, I like calories - the amount of energy required to raise the temperature of one gram of water one degree Centigrade (oh yeah, I guess we call that Celsius these days). It takes about 600 calories per gram for the state change from liquid water to water vapor. So, to make things easy, if you start with 1001 grams of water (1.001 liters) and evaporate off 1 gram, the latent heat of vaporization is enough to cool the remaining water .6 degrees C.
So it is the water that is cooled by the evaporation and that the cooling of the air is due to heat transfer from the air to the water, and that the contrast of the specific heats involved, including the heat required for the state change, make it work out that both the air and the water are cooled. Cool.
Thanks for the prod to get me past my mental block! I am smart enough, but never made it past high school (where I paid scant attention to this stuff) and it's hard to remember back that far.