Where do clouds come from?

Soft and white, clouds drift across the sky like floating cotton wool. But what are they made of, and how do they get up there? The surprising answer is water — water that was invisible just moments before.

Invisible water rises up

All around us, water is quietly turning into a gas called water vapour. It rises off lakes, plants and warm ground and floats upward, totally invisible. The air carries it higher and higher.

Cooler air changes it back

The higher the vapour goes, the cooler it gets. When the vapour cools down enough, it turns back into tiny drops of liquid water. This change is called condensation.

Droplets gather on specks of dust

Up in the sky float teeny bits of dust and salt, far too small to see. The water droplets form right around these little specks, like clinging to a tiny hook.

One droplet is much too small to spot. But when billions of them float together in one place, you finally see them — a cloud! That’s why a cloud can change shape and even disappear: it’s just little droplets drifting, growing and fading away.

Wonder fact: Clouds may look fluffy and solid, but if you flew through one it would feel like cool, damp fog — you could wave your hand right through it!