Here's how it works:

* Water vapor (gas) in the air cools down.

* As it cools, the water molecules slow down and lose energy.

* This causes the molecules to get closer together and change from a gaseous state to a liquid state.

You see condensation all the time:

* Dew forming on grass in the morning.

* Fog forming on a cold day.

* Clouds forming in the sky.

* Water droplets forming on a cold glass of water.

Let me know if you have any other questions!