What is radiational cooling?

Warm days that turn into cooler nights are thanks to radiational cooling.
Published: Oct. 10, 2023 at 1:27 PM CDT
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QUAD CITIES, Iowa/Ill. (KWQC) - Monday we had highs in the upper 50s to lower 60s. We had sunshine and fair-weather clouds, and after sunset once we lost the daytime heating, those clouds dissipated leading to a clear sky overnight, allowing temperatures to quickly drop through the 50s, 40s, and eventually into the 30s.

The NOAA Glossary defines radiational cooling as the cooling of the earth’s surface. At night, the earth suffers a net heat loss to space due to terrestrial cooling. This is pronounced when you have a clear sky.

The weather conditions have to be just right for ideal radiational cooling.

Whether it’s clear or overcast during the day, the sun emits shortwave radiation that heats the ground.

At night, the heat then escapes back toward space.

If the sky is mostly cloudy, some of the heat is then trapped and escape, being re-emitted back to the surface, keeping temperatures warmer. Think of this like a blanket keeping you warm at night.

However, if the sky is clear the heat is able to escape back into space, allowing the air to cool more quickly and efficiently, leading to colder nights.

This tends to happen when the winds are light.