Ask Todd: Fall fog

11:27 PM, Oct 4, 2012   |    comments
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A viewer asked "Todd, why does fog form so often on fall mornings?"

That's a great question! And remember, fog is actually just a cloud that forms close to the ground. The ingredients needed for it tend to come together during the long, cool nights of fall.

Autumn days can still get relatively warm, with plenty of invisible water vapor in the air. Clear, lengthening nights allow the air to become saturated as it cools to the dew point temperature.

Fog forms from the ground up, becoming thickets around dawn.

After sunrise, heating from the sun and the mixing of higher altitude winds down to the Earth's surface help to dissipate fog layers.

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