When cooking food and you turn OFF the gas, why does a lot more steam rise up than when the heat was on?


And when the gas is turned back on, the steam subsides…?

In: Physics

You’re not seeing steam, you’re seeing water vapour. Steam is an invisible gas, water vapour is what happens when steam cools a little and starts to condense out into the air, or what comes off hot water.

When you turn the heat off the production of new steam stops immediately, so all you see is the water vapour coming off the hot water.

Turn the heat back on, and steam starts being produced again which as I say, is invisible.

The water vapor rises from the food and condenses as it mixes with the cooler air in your kitchen. The colder the air it mixes with, the more it condenses and the more visible it is. When the heater is going, as well as cooking your food, it’s also warming the air, causing it to rise above the burner. When the burner is turned off, the warm air column it was creating goes away, the water vapour mixes with cooler air and condenses more.