By Marty Russell
At exactly 12:16 Tuesday afternoon, two things happened: First, the bottom fell out of the skies over Oxford just as I was exiting my truck to go get some lunch, drenching me and soaking my canvas Chuck Taylor high-tops leaving me with cold feet for the remainder of the afternoon. Secondly, the sun at that exact moment reached its northernmost point for another year, marking the astronomical beginning of summer.
The beginning of summer also signals the approach of the Dog Days of Summer, that period of intense heat that lasts roughly from the first week of July until the second week of August. Given the record high temperatures we’ve already experienced in June, technically still spring, it’s scary to think what might lie in store in the weeks ahead.
We’ve been over this before but maybe you weren’t paying attention so it bears repeating. The summer heat is not the result of the Earth being closer to the sun or the conjunction of the sun and the star Sirius, the Dog Star from whence the Dog Days of Summer get their name. The former is a common misunderstanding, the latter just plain goofy, to use a dog metaphor.
While it would seem to make sense that the Earth gets hotter because our orbit takes us closer to the sun in the summer months, particularly with those large solar flares we’ve all seen videos of recently that resemble me lighting a barbeque grill, the fact is we are at our fartherest distance from the sun in early July. We are actually much closer to the sun in early January. So why the heat?
The summertime heating is the result of two things, the angle of the sun’s rays striking the Earth and the number of hours of daylight. As I said earlier, the sun on Tuesday reached its northernmost position in the sky, putting it almost directly over the Northern Hemisphere which is where we live. Because the rays are hitting us from almost directly overhead, they’re more focused and not spread out as they are in the winter when the sun is over the Southern Hemisphere. That, combined with the longer daylight hours of summer, produces our summer heat.
The ancients believed the heating occurred because Sirius, the brightest star in our skies, rose in conjunction with the sun in the summer months and its heat combined with the sun for a double whammy of scorching rays. Because Sirius is one of the stars that make up Canis Major (the Big Dog), those weeks of intense heat became known as the Dog Days of Summer. Of course, we now know that, because Sirius is so far away, its heat has no effect on the Earth.
The good thing about the beginning of summer, though, is that it really marks the end. Starting today and for weeks to come, if you mark the sun’s position you’ll see that it has begun moving southward again. In other words, it’s all downhill from here.
Marty Russell writes a Wednesday column for the Daily Journal. He can be reached at 222 Farley Hall, University MS 38677 or by email at firstname.lastname@example.org.