what is condensation?

Evaporation and condensation are two processes through which matter changes from one state to another. Matter can exist in three different states: solid, liquid or gas. In evaporation, matter changes from a liquid to a gas. In condensation, matter changes from a gas to a liquid.
All matter is made of tiny moving particles called molecules. Evaporation and condensation happen when these molecules gain or lose energy in the form of heat.
Condensation

An example of condensation can be seen when drops of water form on the outside of a glass of iced water. The drops seem to appear from nowhere, but they actually form from water vapour in the air. The dew that forms on grass overnight is another example of condensation.

Condensation happens when molecules in a gas cool down. As the molecules lose heat, they lose energy. As a result, they slow down. They move closer to other gas molecules. Finally, these molecules collect together to form a liquid.
So there you are!. If you have it say in the bathroom mostly after shower or bath and the walls are dripping with condesation [wet] then it's bad ventilation think about fitting an extractor fan. No not brainy took this from an encyclopaedia or in otherwords cheated.

Here's one to try, blow in a clear plastic bag tie off the top and put it in the fridge for around 5mins and when your breath inside the bag cools droplets of water appear in the bag 'condensation'.

bob
November 2008