When the sun comes up, where does the morning fog go?
Look at the field… it's full of soft, cloudy fog! You can hardly see the little tree. Fog is just lots of teeny tiny water drops, floating in the cold air. Now the warm sun is peeking up… and something is about to happen to the fog. Ready to guess? When the sun comes up… will the fog run away, or melt away right where it sits?
After you watchWhen the sun comes up, where does the morning fog go?
The short answer
When the sun comes up, the morning fog melts away right where it is — it does not run away. Fog is made of tiny water drops floating in cold air. When the warm sun heats the air, those drops turn back into water you can't see, so the fog seems to fade away on the spot.
Try this next
- What if the night stayed warm? Guess first: would there be any fog in the morning at all? Then bring the sun up slowly and watch.
- What happens when night comes back? Guess whether the same field gets foggy again when it turns cold. Then watch the fog come back.
The whole story
How it works
Cold air can only hold a little bit of invisible water, so on a cold morning the leftover water turns into tiny drops you can see — that's fog. When the warm sun heats the air, the air can hold that water invisibly again, so the drops turn back into hidden water right where they were. The fog doesn't move away — it just becomes invisible in place.
What people get wrong
Lots of kids think the fog blows away to somewhere else, like a little cloud that travels. But most morning fog melts away right where it sits — no wind needed. The warm sun lets the air hide the water again, so the fog turns invisible on the spot.
The catch
The warm sun makes the fog disappear, but the water never actually leaves the air. So when the next night gets cold again, that same hidden water turns back into fog — right in the same field.
Questions kids ask
Why does fog show up in the morning?
The air is coldest in the early morning after a long, chilly night. Cold air can't hold all its water invisibly, so the leftover water turns into tiny drops you can see — that's fog.
Does the fog blow away or melt away?
It melts away right where it is. When the warm sun heats the air, the air can hide the water again, so the fog turns invisible on the spot — no wind needed.
Is fog the same as a cloud?
Yes! Fog is a cloud sitting on the ground. Both are made of tiny water drops floating in the air.
Talk about it
- Guess first: where do you think the fog goes when the sun comes up?
- If the water is still there but we can't see it, where do you think it's hiding?
- Why do you think the field was foggy but the warm kitchen wasn't?
For grown-ups
Air holds water as invisible vapor up to a temperature-dependent limit. On a clear, calm night the ground chills the air below its dew point, so the excess water condenses into tiny droplets — fog (a cloud at ground level). After sunrise the air warms, its capacity rises, and the droplets re-evaporate, so the fog 'burns off' in place rather than blowing away. The amount of water barely changes — only whether you can see it.
Keep going
What else makes you wonder?
- Where do you think all that water hides when the fog is gone?
- Why does your breath turn foggy when it's cold but not when it's warm?
- Could you make a little fog of your own on a cold day?