Evaporation and Condensation

The science behind condensation

The formation of a liquid back from a gas is the opposite process to Evaporation - it is called Condensation.

A good example of mechanical condensation is an old fashiouned steam train.  In a steam locomotive the used steam (gas) is released to the atmosphere where the pressure becomes suddenly reduced - making the familiar chuff chuff noice. It turns into tiny droplets of water that you see as a white cloud rising from the train's engine in the video below.

The water droplets mix with the air and dissolve becoming invisible. 

Condensation shortcuts

Sometimes a substance takes a shortcut and misses out the liquid stage going straight from solid to gas. Do you know what that is called?

This type of phase transition, or change in a state of matter, is just like melting, freezing, and evaporation.  But the substance changes from a solid to a gas without ever passing through a liquid phase. Dry ice, solid carbon dioxide, provides a common example of this -it's called sublimation.