How does rain water evaporate without boiling?

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We had a summer rain shower yesterday. Afterwards I could see steam rising off the street as the water evaporated. I could walk barefoot on that street before the shower and while the water was evaporating. If the water was boiling away, surely I wouldn’t be able to walk across it without scalding my foot.

What’s going on here?

In: Planetary Science

12 Answers

Anonymous 0 Comments

This isn’t exactly what’s happening, but for the sake of understanding this think of the liquid water as a bunch of bouncy balls jostling around in a container. If you just shake the container a little, the balls will mostly sit there hitting each other, but occasionally a ball will hit other balls just right to bounce high enough to fall out of the container. This is the water evaporating: sometimes an atom happens to have enough energy to just break free.

Boiling the water would be like shaking the container violently enough that the balls have to leave (you’re just shaking them out of the container now). If evaporating is one of the balls happening to bounce against the others hard enough to escape, boiling is when the balls are bouncing so much collectively that they can all escape.

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