Why can you see your breath when it's cold?

Hook

Why and how can you see your breath when it's cold? It looks like smoke, but it's actually a tiny cloud you made yourself.

Breath

Your breath is warm and full of water vapor, an invisible gas that comes from inside your lungs.

Cold

When that warm, damp air hits cold air outside, it cools down fast.

Dew

Cold air can't hold as much water vapor as warm air. So the vapor condenses into millions of tiny liquid droplets.

Cloud

Those droplets scatter light, and that's the white fog you see. It's the same way real clouds form in the sky.

Fade

Then the droplets mix into the drier air around you and evaporate again, so the cloud disappears in a second or two.

When

The colder and more humid the air, the easier it is to see. On a damp winter morning, you'll see a big puff. On a warm day, nothing.

Close

So you can see your breath because cold air turns its water vapor into a tiny cloud. ThatsWhyHow.