Had this conversation on AIM and I was stumped.
Can anyone explain this to us?
Could have something to do with the “specific heat” of the substance.
Specific Heat refers to the rate at which a substance absorbs/releases heat energy. Alcohol & gasoline would have a low specific heat compared to, say, water or maple syrup.
Heat is related to molecular vibration. Your skin transfers heat to the water and alcohol, which in turn vibrates molecules in each. Could it be that even if water is capable of absorbing more heat as in Andrew’s theory, this energy is transferred back to the skin more frequently (giving the sensation of being hotter) since water has a slower evaporation rate and hangs around longer? Alcohol, on the other hand, evaporates quickly and would carry these vibrating molecules away from your skin at a faster rate. Just a guess.
That’s not what specific heat REALLY is (it’s the amount of energy required to raise the temperature of a substance), but a low specific heat will allow it to reach the substance to reach its boiling point more quickly, thereby giving the cooling effect more quickly.
How cold it feels probably has more to do with the rate at which heat is removed. Alcohol is more volatile than water, I think.
And in addition, alcohol will always be effective because the atmosphere is seldom saturated, or even close to it, with its vapor which isn’t true of water.