Coming Attractions: the Coldest Day of the Year

If you live in the northern hemisphere, as most of Geezer’s gentle readers do, the shortest day of the year came and went on December 21 (or very very close to it), but the coldest day of the year will arrive shortly. Shouldn’t the coldest day of the year also be the shortest day of the year, the day with the shortest expo
sure to sunlight? Yes and no. If we all lived on a very hard and very reflective surface, like, say, Ben Bernanke’s head, the shortest day might very well be the coldest day. But the earth is only somewhat reflective, and somewhat absorbent–particularly the  wet part. The coldest day of the year depends largely on how much heat is being held by the earth’s surface at and around the place where you live. It also depends on prevailing winds, water currents, and cloud cover. In  short, the coldest day of the year depends on where you live. For a longish and interesting explanation of this, read this piece on seasonal delay, posted by the University of Iowa.