Thermal Physics

States of Matter

On a warm day, why do water droplets accumulate on the outside of glasses and soda bottles?

The water does not seep through the container, but instead comes from the air surrounding it. Water vapor is the gaseous form of water that is in air below the boiling point of water. As discussed above, it takes a larger amount of energy to vaporize water, so the molecules of water in the air have more thermal energy than do the molecules in the colder glass. So when the water molecules strike the glass they transfer much of their thermal energy to the glass. The colder water molecules join together to form water droplets on the glass. The process is called condensation. Condensation also occurs on window panes when the outside is cold and the interior air is warm and humid.


This is a web preview of the "The Handy Physics Answer Book" app. Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App