While heating water in an open container, on gas stove, There is a little or no vapors comming out of the surface of water, but as soon as I turn off the stove, all of a sudden, I see lots of vapor comming out of surface. Can somebody tell me the reason?
Thanks
Sam

Hi:

There are two states here; Water in form of molecular gas - which we call steam which is transparent and can't be seen- and water droplets due to partial condensation of steam -which are very tiny and are what cloud and fog are made of. When first water vapor is produced, it is in the form of steam and can't be seen. Given a bit of time their molecules join and form tiny droplets (fog) which you can see. When your pot is violently boiling on open stove what you have on the surface of water is mostly tarnsparent steam. When you turn off the stove, you produce slowly rising vapor which quickly join each other to form visible droplets of fog.

SA

Maybe it has something to do with the removal of the heat source. When air around the container cools, the watermolecules condensate.