This is a beautiful time of the year with warm evenings, late sunsets. The days are still getting longer. We have two more weeks until things change again. Summer solstice occurs on Saturday, June 20. After that date, the days will be getting shorter but their average temperatures will rise. Nothing to do with global warming. This is the change of the seasons that’s been a mechanism ever since the planet came into existence.
The solstices – June 20 and December 21 – mark the times when the sun is highest (June) and lowest (December) in the northern hemisphere. In Buenos Aires, São Paulo, Sydney, Christchurch and everywhere else south of the equator it’s the opposite, and Christmas happens at summertime there.
Seasons aren’t related to the distance of the earth from the sun. If that were so, both hemispheres would have the same seasons at the same time. The solstices – and their cousins, the equinoxes in March and September – relate to the earth’s axis tilt. Visualize it like this: When you travel the twisty part of U.S. 129 up toward Blairsville, there’s a motorcyclist coming ahead in a left-hand curve. The bike is leaning toward your left, away from you. In the right-hand curve that follows, you see another motorcycle, this time it’s leaning to your right, or towards you. The earth does the same thing. Its tilt out of the vertical, 23.5 degrees, is actually greater than the amount of “lean” that the average motorcycle does in most curves. In June, the northern half of the earth (your car, in the highway example) “leans” toward the sun. In December, it tilts the opposite way. The more our area tilts toward the sun, the higher the sun will appear on the horizon.
Along with the change of seasons, we also get to change the clock on the kitchen wall, basement wall, various wristwatches, appliance timers, clock radios and other devices twice a year. This is not related to solstices and equinoxes, but to arbitrary decisions by the United States Government. Daylight Saving Time intends to fit everybody’s work day into the available sunlight hours. This used to be important when most Americans had to be up before sunrise to attend to the farm. Now, many are wondering if it wouldn’t be best to leave it alone and stay with the current setting.
Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at gainesvilletimes.com.