Why so cold around sunrise?

Why it?s so Cold Around Sunrise?

It?s certainly nice to see the overnight low temperatures back in the 30?s after what we experienced last week and weekend. Last Friday morning we tumbled down to 20 degrees and then Saturday we dropped down to 18!That was the coldest we?ve been since the overnight low was 13 degrees on January 8th, 2005. For those who are interested, the coldest temperature ever recorded in El Paso was minus 8 degrees back in 1962.

Those cold temperatures are made in Mother Nature?s kitchen. We typically have to have several ingredients to get that cold. One is, of course, colder air that comes down from Canada or the Arctic. The second ingredient is dry air. Dry air is easier to cool than moist air. The third ingredient is wind. A light or non existent wind is crucial. The stronger the wind, the more it will mix the air and keeps temps a little warmer. The last ingredient is clear skies ? this allows for radiational cooling. This takes place when heat is radiated away from the ground and into space. Clouds will act as a blanket and keep the heat more toward the surface.

Do you ever wonder why the temperature gets the coldest just before sunrise? Just like your own budget, the Earth has an energy budget. During the day, energy arriving from the sun exceeds energy that the Earth radiates back into space, so temperatures usually rise. At night, the incoming solar energy drops off, but the Earth continues to radiate energy, so temperatures typically fall. Dawn comes after a full night in which the Earth has lost energy and received very little.

It is common that the temperature even falls for a short time after sunrise even though it?s only by a degree or two. If the temperature doesn?t fall as the sun rises, the air may actually feel colder. That?s because we are used to it being colder when it?s dark and warmer when it?s light. When the sky begins to lighten and the temperature remains nearly the same, we might perceive that it is colder than it actually is.