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mr47 t1_j0mro23 wrote

Reply to comment by TonyJPRoss in How does high humidity affect perceived temperature in hot and cold environments? by MindTheReddit

> As you add heat energy to water, its temperature increases linearly until it gets to about 100 degrees C. From here it takes in additional energy, but its temperature doesn't rise - this energy is instead used to break its bonds to complete the phase change from liquid into gas. Once the phase change is complete and it has become a gas, you see a linear relationship between heat and temperature once again. > > So what's happening is you're transferring your body heat into the sweat, which is evaporating and carrying that energy away.

While technically correct (if you read the two passages separately), it seems as if you imply that sweat reaches 100 degrees C prior to evaporation. It does not.

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TonyJPRoss t1_j0mwe8v wrote

What I always thought was that a single molecule of water might have enough energy to change phase, even if the temperature of "the water" isn't that high. The energy of the water molecules follows a bell curve with a long tail in the high energy end - the evaporating particles are in that tail.

https://physics.stackexchange.com/questions/521843/why-most-distribution-curves-are-bell-shaped-is-there-any-physical-law-that-lea

But wind has such a strong effect on the evaporation rate that I think this explanation must be lacking something. Do you have any insight?

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Chemomechanics t1_j0qky4o wrote

At an interface, it’s very likely for just-detached molecules to be deflected right back to the surface by the surrounding atmosphere, where they reattach. This is less likely to happen if convection is carrying them away, so the evaporation rate increases with wind.

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