Solar radiation heats the ground during the day. At night the heat escapes towards space. A blanket of clouds can re-emit some of the heat back to the surface.
On clear nights, the radiation escapes into space, creating cooler temperatures. So that sunny winter day that felt okay, is now a bone-chilling night.
When cold air takes over it can cause problems.
Most roads lose heat evenly…roads have ground to help insulate them. Cold air can reach above and below bridges, resulting in quicker heat lost.
That’s why you see those “Watch for Ice on Bridge” signs, and why WTWO meteorologists frequently mention bridges and overpasses freezing first.

Radiational Cooling