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Name: Jack
Status: student
Age: 13
Location: N/A
Country: N/A
Date: 2000-2001
Question:
Why is the coldest time of day right after the sunrises??? I would expect the sun to heat the earth and the coldest time of day be before visible light hits the surface and the sky is still dark.

Replies:
Jack-

The earth continuously radiates heat into space and receives heat from space. The change in temperature is controlled by the balance between these two. Even as the sun begins to rise, the balance is tipped toward a loss of heat... therefore temperature goes down.

Larry Krengel

Jack,

Because the Sun is so low to the horizon at sunrise, most of the energy is absorbed by the distant atmosphere. Meanwhile, for cloudless skies at least, energy from the Earth's surface continues to be lost to the atmosphere directly above. Thus, the lowest temperature of the night can still occur after sunrise.

David Cook
meteorologist working at Argonne National Laboratory

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