3Condensation and clouds
As moist air rises it expands and cools. Once it reaches its dew point, water vapour condenses onto tiny specks of dust, salt or smoke, the condensation nuclei, and the droplets gather into a cloud.
Why do clouds usually form high above the ground rather than at the surface?
Salma and Omar, right: rising air cools until it reaches its dew point. Nour, cooler air holds less vapour, not more. Maya, good guess, but it's the cooling that makes the vapour you see as a cloud.
A cloud is tiny liquid droplets or ice crystals. Water vapour itself is invisible.
the vapour you see as a cloud




