Hacker News Reader

> using boiling water in snow-making machines

The seems like a related effect: https://www.youtube.com/watch?v=IQ3kQPWlU-o

So evaporating water cools the surrounding air?

Yes. To transition from liquid to gas the water must absorb heat. That heat must come from the air, cooling it.

Does the same effect happen with 100% relative humidity?

Or, perhaps even more well known to Canadians, Zambonis use hot water to resurface rinks.

Also,the "hot water pipe freezes first" is a popular "myth" (turns out it may be true). This has happened to me and the plumber seemed to take that for a fact despite not having a reasonable explanation.