Clouds Radiate Heat

Night sky photo from Wikimedia Commons, arrows and text added

Now that the weather is colder here’s something to ponder: Why is it warmer on a cloudy night?

Some people say it’s warmer because clouds act like a blanket to hold in the heat but that’s not scientifically true.

Clouds are not holding in heat. They are emitting it!

Clouds absorb heat during the day just as the earth does. When the temperature falls clouds emit heat in all directions including downward to us below. Their warmth can be just enough to keep us above freezing.

On a clear night there is nothing to warm us so we have frost in the morning.

Did you know you can avoid frost on your windshield if you park beneath a tree on clear, near-freezing nights? The tree is emitting heat, too. No frost in the morning.

Either it is very cold in this picture or the car was not parked under a tree.

Frost on a car windshield, London (photo from Wikimedia Commons)

Read more about cloud blankets and other scientific “facts” that aren’t true at Dan Satterfield’s Wild Wild Science Journal.

(photos from Wikimedia Commons; click on the captions to see the originals)

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