When wet food or water is boiling I don’t see a lot of steam, but if I turn the heat down I see more steam. Why?
In: 15
The water in the pot boils into water vapor, a colorless gas. The visible “steam” that you see are tiny liquid water droplets that have condensed and are suspended in the air. This condensation depends on both the surrounding temperature and the amount of vapor that’s already held in the air, although the amount of vapor that the air can hold also depends on its temperature (cooler air has a lower vapor capacity). When you turn the heat on your stove down, the air above the pot cools, lowering the vapor capacity of the air, which means more vapor condenses out as visible water droplets — this seems to me to be the likely dominant effect.
This is one of those everyday science problems that is extraordinarily simply in principle but can be especially tricky to explain correctly. That’s why I got help from a [SciAm Q&A about a steamy bathtub](https://www.scientificamerican.com/article/how-does-bathwater-give-off-steam/). A friendly further reading on water vapor, condensation, air capacity, etc. is this minimal-math [SHSU weather lecture](https://www.shsu.edu/~dl_www/bkonline/131online/f09water/09index.htm).
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