I always assumed the way sweat cooled us was how the water on the outside of our skin cools off and in turn cools the skin down however I don’t get why the air that cools the sweat cant cool our bodies especially if our skin can heat that sweat just as fast or faster than the air can cool it.
In: Biology
Follow up question. Why does our body lose heat to water touching our skin faster than it loses heat to air touching our skin?
The air will slowly cool the skin but moisture helps cool it faster because the phase change from liquid to gas requires energy that the molecules absorb and carry away when they evaporate
You are hot.
You sweat.
That sweat is full of your heat.
The hot sweat evaporates.
You just lost some heat because the heat was in the sweat. And the sweat just left you.
So long as the air is relatively dry, any moisture on your skin wants to jump off into the air, to balance it out. Think of it kinda like a sponge, if the sponge is dry, water will move into the sponge. Except, in order to absorb into the air, water on your skin needs to evaporate.
So … crazy things happen when matter changes state. When anything moves between solid, liquid or gas (aka evaporates, thaws, freezes, or condenses)
When the water in you skin evaporates to join the air, it will basically absorb a bunch of energy (heat) in order to boil itself off.
I’m oversimplifying, but the phase change is the key. It’s also why humidity is dangerous. If the air is already wet, the water/sweat on your skin can’t evaporate out, and you’ll overheat super easily.
Because when it dries, it takes heat away from our body. The sweat on your skin turns into vapor and disappears into the air, and this helps cool you down.
Air alone doesn’t cool us as much because the sweat drying takes more heat from our body than just air moving around.
I think you’ve got your answer from the other comments but if I had to ELI5:
Sweat is composed of small molecules which are loosely bound to each other – but they are constantly moving around and always trying to escape. One way to escape is heat – which is readily available from our skin. So these sweat molecules take the heat from our skin so that they can break free. This leads to two things – the sweat evaporates (because the molecules have broken free from each other) and our body cools down (because the molecules took away some heat)
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