What Causes ‘Fog’ to Form at Night?

Fog happens when cool air meets warm, wet ground at night. Imagine you're in a room with hot soup on the table, steam rises from it because the warm air holds more water vapor than the cold air around it. Fog is like that steam but outside, and it makes everything look blurry.

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Examples

Your breath becomes visible in the cold morning air, that's like a tiny version of fog.
Steam rises from a kettle on the stove, just as fog rises from the ground at night.
The classroom looks hazy during a cold morning, it’s fog, but close to home.

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Categories: Environment · fog,weather,science,atmosphere