Steam is formed at 100°C but I see “steam” being produced at less than that temperature. What is that and why isn’t it steam?
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At pretty much any temperature, there’s some amount of water converting into water vapor. Behold: [edit: grabbed the wrong visual the first time; let’s try this.]
[https://en.wikipedia.org/wiki/Vapour_pressure_of_water](https://www.engineeringtoolbox.com/docs/documents/599/Water_saturation_pressure_C.jpg)
The amount of the water that converts into vapor goes from “miniscule” at cold temperatures, to “a fair bit” at warm temperatures, “quite a bit” at 80-90C, to “100%, just give it a minute” at 100C.
In other words, the equilibrium favors liquid as long as you’re below 100C, but once you cross 100 degrees the equilibrium shifts to favoring gas. The energies of the particles are distributed in a bell curve (I forget if it’s normally distributed, but that’s the general shape) so in cold water we have “only the top 0.1% are energetic enough to vaporize” and that number increases until somewhere above 100 degrees we’re at “only the lowest 0.1% would have low enough energy to condense”.
I’m fairly sure the wisps we see above hot water are actually condensed water droplets, like a cloud. So yes, that region is rich in H2O gas, but what you’re seeing isn’t the gas, it’s tiny bits of liquid being carried upward because they’re suspended in a plume of hot gas.
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