Why are clear nights so cold?

March 12, 2008 1:29:53 PM PDT
Clear skies allow heat that we get from the sun during the day to exit the atmosphere at night.

Erica's Answer:

Of course, sunlight heats the Earth's surface during the day. At night, that heat radiates upward, into outer space. If clouds are overhead, less heat can escape, so we stay warmer overnight. But if the sky is clear, there is nothing to block the warmth from escaping into outer space!

- Erica