this post was submitted on 14 Feb 2026
293 points (96.2% liked)
Greentext
7776 readers
1157 users here now
This is a place to share greentexts and witness the confounding life of Anon. If you're new to the Greentext community, think of it as a sort of zoo with Anon as the main attraction.
Be warned:
- Anon is often crazy.
- Anon is often depressed.
- Anon frequently shares thoughts that are immature, offensive, or incomprehensible.
If you find yourself getting angry (or god forbid, agreeing) with something Anon has said, you might be doing it wrong.
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Enter vapor pressure:
Basically water always evaporates if the air is completely dry, until the air contains a certain amount of water (measured in partial pressure, which is the part of the air pressure that is caused by water vapor). This partial pressure is temperature-dependent, so if you have 20°C (normal room temperature) you're gonna have 23 mbar of water vapor partial pressure in the air. Source
So water still evaporates at lower temperatures when the air is dry enough. It's just that at 100°C ("boiling point of water"), that partial pressure of water vapor in the air increases to 1013 mbar which is equal to the total pressure of the air; In other words, at that temperature in equilibrium, the air is totally made up of water vapor and nothing else. If you increase the temperature above that, the water vapor partial pressure tries to still increase, which makes the total pressure go above normal air pressure, which causes a pressure gradient and causes the air to move with mechanical force, which you can use to make turbines spin.
A more microoscopic explanation is due to Maxwell-Boltzmann distribution.
First, you need to underestand temperature. The difference between cold and hot water is the average speed at which particles move, with hotter water's particles moving faster.
But this is just the average speed, it turns out that particle's speed can be se en as a random variable, and they follow Maxwell-Boltzmann distribution:
So you have a small proportion of particles that move very fast, even in cold water. If some of those particles get (or collide with other particles near) to the "layer" of water that is on contact with the air, they will have enough energy to escape water's superficial tension, thus going into the air and out of the water body. The higher the average speed of the particles, the faster this process will go. Finally, the rate at which this process happens also depends on the energy required to be able to leave the water body, which depends on factors like air pressure.
yeah i've of course heard about it and i'm studying physics myself rn so i'll get to it.
I simply haven't taken the course on quantum physics yet so i don't want to make bold claims here. I have yet to derive the classical phenomena from quantum physics myself.
Thank you ive always wondered about this but never wondered about it when I had the chance to look it up and now I know :)
You're welcome :)