Weather Wise: Here's why it's colder in the morning than it was last night

Posted at 12:19 PM, Oct 12, 2016
and last updated 2016-10-12 12:19:30-04

CINCINNATI -- Here’s a common scenario: You wake up to head off to work or school. After taking one step out the door, you run into a wall of cold, dry air, forcing you to go back inside to grab a coat for your morning commute.

Why did temperatures drop so quickly through the overnight?

The answer: radiational cooling, a process that allows the ground and the air nearby to cool quickly when certain weather conditions are in place.

Here are the ingredients for a super-chilled evening:

  1.   Clear skies
  2.   Dry air
  3.  Light winds

The sun’s rays warm the surface and the air nearby, but when the sun sets, that same energy tries escaping back into the atmosphere. Clouds tend to act like an atmospheric blanket throughout the overnight hours, helping to hold in some of the solar energy collected from the day before.

Without our blanket, the heat quickly escapes back into space, and temperatures can drop in a hurry.

Moisture also can help to trap heat, so with dry air in place, the heat is more readily able to get away through the night.

Light or no winds also can help to hold cool air in place, not allowing it to mix or heat due to friction.

So before you head out the door, peek out the window first. If you can see the moon and stars with a lack of cloud cover and no rustling in the leaves, odds are it will be a very chilly morning.