Mixing It Up

It seems counterintuitive, but our wind overnight actually helped keep us warmer! Wind at night mixes up the lower layers of the atmosphere, and that prevents the air near the surface from stratifying, which allows the coldest air to settle near the ground where we live.

Air temperatures on windy and calm nights

Standard air temperature is taken at the 5 foot level. Did you know that on clear calm nights the air can be as much as 5 degrees colder at the ground than at 5 feet? That means you can have frost on the ground, even when the “shelter” air temperature is at 36 or 37 degrees.

Ever notice how the coldest temps seem to come right after sunrise? That’s because the sun is not yet high enough in the sky to allow the rays to strike the ground and begin warming the lower atmosphere. So especially in winter when the sun angle is low, we often see our minimum temperature about 30 minutes after sunrise!

Our winds will ease later this afternoon, and after the coldest night tonight with clear skies and calm air, look for temps to rebound this week. We should be in the 50’s this weekend!

PH

  • billobars

    So Paul,

    At the top of this item, might that not be the opposite of wind chill? If so, what should we call it?