Why can we see our breath when it's cold?
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What shapes do you think your breath clouds could make on a cold day?
What about...?
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Transcript
Have you ever seen a little cloudy puff when you breathe outside in the cold?
You breathe out warm air that has water in it. In warm air, this water is an invisible gas.
Outside, cold air cools your breath very fast. The water gas changes into tiny drops, like a little cloud.
Those tiny drops catch the light as they float away. That is why your breath looks white on a cold day.
So that cloudy puff is water from your breath turning into tiny drops in the cold air. It is like a little cloud you made!
For grown-ups: the science
We can see our breath because water in our warm breath turns into tiny drops in cold air.
Exhaled air is warm and humid. When it mixes with colder air, it cools below its dew point, so water vapor condenses into tiny droplets that scatter light and look white; in very cold conditions, some may freeze into ice crystals.