Things that make my head hurt, pt. 189

Last week dawn finally started coming earlier. I know, the solstice was back in December, and that was the shortest day of the year. But if you look at the table of sunrise and sunset times for Cape Girardeau, you see that the sun didn’t start coming up earlier until Jan. 10. All the day lengthening initially happened in later sunsets. Why? I’m sure lots of people understand this, but I’m not one of them.

More important to me is the table of civil twilight. There are three kinds of twilight, as you know if you’re in the habit of reading the weatherunderground.com page; civil twilight, nautical twilight, and astronomical twilight. At one point last fall I made the optimistic error of figuring it would be okay if I got home on my bike before the end of nautical twilight. It’s not.

During civil twilight, it’s light enough to do things outdoors without artificial lighting. During nautical twilight, it’s light enough to see the horizon so you can use your sextant to see how high various bright stars or planets are. During astronomical twilight it’s still too bright to observe distant galaxies. What this means in practical terms, to someone riding his bike 15 to 20 miles to get home, is that you need to get there before the end of civil twilight unless you like riding in the dark. I don’t mind starting before C.T. in the morning, since traffic is light — and besides, there’s something reassuring about it getting lighter as you go — but I don’t ride on rural roads in the dark in early evening, when traffic is invariably pretty heavy. Even with my super-bright green lantern headlight.

The take home message from the table is that it’ll be the middle of March before I can leave work at 5 and be sure of getting home before dark. Actually, March 9, since Daylight Saving Time starts then. This also means that for a few halcyon days, March 3-8, it will be light when I leave the house at 6, but then it won’t be again until April 12.

Meanwhile, my new route to work is a big improvement. County road 621 seems to be populated with an entirely different set of drivers than State Road W. I guess you don’t take the winding, hilly, scenic road if you’re in an insane hurry to get to or from work.

3 Responses to “Things that make my head hurt, pt. 189”

  1. Cabell says:

    “Green lantern headlight”? Do you have a magic ring that I don’t know about?

  2. K says:

    Is the link to the sunrise/sunset table supposed to point at that admittedly admirable lolcat?

  3. Allen says:

    No, that was a mistake. But I like it better than a sunrise/sunset table anyway.

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