Be careful !

For reasons not too difficult to understand, driving during the winter on sunlit days can be especially bothersome (and dangerous) because of the ubiquitous and very intense glare of the low-lying sun.

On December 21 (winter solstice) the sun is directly over the Tropic of Capricorn, 23 degrees S (Rio de Janeiro). Observers in New York latitudes on that day will observe that the sun’s altitude over the horizon at 9am and 3pm can be as low as 12 degrees. In the illustration above, the blue line just below the word Winter is the altitude subtended by the sun at about 9am and 3pm on that day. The red line is the declination of the sun at 12:00 noon, its zenith for that date. This means that unless you are turned completely away from the sun, its incandescent beams are coming right through your windshield or the side windows.

In contrast, on June 21 (summer solstice) the sun is between 50 and 72 degrees above the horizon. Its beams bounce off the tops of our vehicles and our vision is not distracted by glare. Incidentally, (for reference) Havana is only a few miles south of the Tropic of Cancer, 23 degrees N. Whereas during the solstices, the sun is directly over those cities at 12:00 noon, the highest the sun rises over New York’s northern suburbs on June 21 is about 72 degrees. I must emphasize, the angles just quoted remain pretty much the same for about two weeks before and two weeks after the solstices.

By the way: Whatever you may think of its relevance, the illustration above was not the result of spontaneous generation. Needing a graphic image of a protractor, I checked in with Google, where I was able to copy an image from one of the many sources it offered. Taking it to my photo program, I edited out everything extraneous with a cloning tool and brought it to WordPerfect. While there, the four lines subtending through the arc of the protractor were easily inserted. The image of the Sun came from WP’s clipart disc and then, using the printed composite, I scanned it to file and placed it in my photo album. The blog program makes it a simple task to retrieve images for inclusion into postings. I wrote all of the above, to show people who are unfamiliar with these processes, how infinitely accessible and fascinating are a computer’s resources, even for such rank amateurs as you and I.