Try to answer this weather trivia question: On average, when is the coldest time of the 24-hour day? Your answer options are sunset, midnight, 3 a.m. or sunrise. Here’s some background before I reveal the answer.
The sun heats Earth. Sunshine is probably the way you think of the sun’s warming powers, but the warmth is simply radiation. It’s the same radiation that penetrates clouds to warm the ground, even when you can’t see the sun. A lower sun in December, combined with fewer minutes of daylight, is why we are colder than we were six months ago.
Most folks miss the right answer to the question of when the coldest time of day is. I think it’s because people answer based on their lifestyle, work schedule or just their perception. Do you get cold when you are tired, sitting still or after a big meal? That would throw you off because that chill is based on physiology.
Frequent answers to my quiz for the coldest time of day are midnight or 3 a.m., but both of those are incorrect. It could be people are thinking that if the middle of the day is the warmest period, then the middle of the night, 12 hours later, would be coldest. Maybe it’s that if you get up in the middle of the night and tiptoe across a cold tile floor in your jammies — it just seems cold.
Here is the answer: The coldest time of day is actually a few minutes after sunrise! Strange, but true. When people ask me, “How cold will it get tonight?” I often give the answer with a late night or early morning reference, or I just call it the morning low since the lowest temperature is reached after the night is done.
The next time you lay awake pondering the universe, unable to drift off to sleep, just get up and check the temperature every hour. Somehow, I don’t expect you to do that, but at any time you can pull up hourly temperature data online to verify the daily temperature cycle.
Why sunrise is the coldest time of a typical day is simple. After sunset, the heat the ground absorbed during the day radiates out to space. With light wind and low humidity, the air temperature will keep on falling until something heats it up. That something is the sun’s rays.
Why don’t we heat up the minute you see the sun? Air does not absorb and retain heat very well, compared to the ground. While air is partially heated by sunlight, most of the heat we feel is from sun rays or radiation striking the ground, so the ground warms and then the ground transfers the heat to the air.
Think of all of this as a pot of water on the stove. The water won’t warm until you turn on the stove. After you turn off the heat, the water will keep cooling until the heat is turned back on.
This page is available to our local subscribers. Click here to join us today and get the latest local news from local reporters written for local readers. The best deal is found by clicking here. Check it out now.
Already a member of the Lagniappe family? Sign in by clicking here