It certainly was a lot colder this morning (Dec. 1st) than it was yesterday (Nov. 30th). Yesterday’s lows got to 30ºF, but felt a lot colder due to the wind. This morning’s lows were pretty much the same as the feel like temps but the actual air temp was just that cold.
A large part of why it was so cold this morning is due to winds being calm and skies being clear. That mixture is ripe for a frigid start in the mornings. This happens due to two contributing factors, one being the lack of clouds.
Clouds during the overnight hours will trap some of the heat that is left over from the surface or the air itself. This helps keep temperatures a bit more mild as the clouds act like a blanket. Now, during the day this can have the opposite effect as the clouds will block most of the heat coming to the surface.
The other contributor to the cold start today was the lack of winds. Yesterday morning winds were between 15 to 20 miles per hour, gusts at times got to 30 miles per hour. So how does the wind actually warm the air when it makes everything feel so much colder.
Well, that’s because the wind acts like a big mixing spoon. Much like when you boil water or cook noodles, or anything for that matter, we stir our food to evenly heat what we are cooking. The wind acts in the same way, as winds higher up are faster it helps stir the air around overnight so temperatures can stay more consistent and mild. So when there is no wind, the air doesn’t get mixed around and the surface temperatures cool off rapidly.
The reason we the winds make temps feel colder is due to evaporative cooling, but that is an explanation for another day.
In today’s case we had both factors at play, lack of winds to mix the air and lack of clouds to keep the heat in. Yesterday, that was the case, but today was significantly colder for that reason.