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DST potpourri

November 7, 2010 at 1:56 PM by Dr. Drang

Not sure when I’ll get around to posting this, but I’m typing it on my iPhone while sitting in a school cafeteria on a chilly Sunday morning. I’m “attending” a swim meet, which, if you’ve never done it, consists of

  1. driving your kid to the meet at least an hour early so he can do warmups;
  2. sitting in a holding pen—a cafeteria or gym—for four or five hours as you wait for your kid’s events; and
  3. going to the pool itself just a handful times to watch your kid swim for a minute.

It’s still less boring than baseball.

This is, to my knowledge, the first time I’ve had to get up for one of these things the morning after a time change. As I was setting the alarm on my iPod last night, I began to wonder about how it was going to handle the switch from Daylight to Standard Time and whether I should manually change the time before I fell asleep.

My sense was that the iPod—a second-generation Nano—would do nothing, making it safe for me to change the clock ahead of time and set the alarm for 6:00 AM CST. But what if it changed its clock overnight? Then it would be running an hour late, and the alarm wouldn’t wake me in time for the meet.

To be on the safe side, I left the clock as-is and set it for 6:00 AM. Of course, it didn’t change overnight, and woke me an hour early. How did I know it hadn’t changed? I looked at my iPhone and saw that its time was an hour earlier than the iPod’s.

(My wife left a distinctly unhelpful note by the clock in our bathroom: Remember the time change. How that was supposed to tell me whether she’d changed the clock, I’ll never know.)

From the forgoing, you might think I’m one of those people who hate DST and the biannual ritual of changing the clocks. Not at all.1 If we were on Standard Time the whole year, I’d be getting awakened at 4:00 AM all summer by the birds outside my window. No, thank you; much better to have that hour of daylight at the end of the day.

Conversely, if we stayed on Daylight Time all year, winter mornings would be even bleaker than they are now. Most of you probably don’t remember the energy crisis of the 70s. Long lines at gas stations weren’t the only inconvenience. One year, in a misguided attempt to save energy, DST was kept year-round. It was awful. Kids went off to school in the pitch dark, without even the warmth of the weak January sun.2

DST has been part of the Apple news lately because of the alarm bug in iOS. Apple’s description of it is an odd mixture of the specific:

And the fuzzy:

Unlike the Zune leap year bug of a couple of years ago (which will reappear in two years if you still have a Zune of that generation), the iOS bug is a mystery to me. My sense is that a bug that hits some alarms but not others must be buried pretty deep in the code. But since it isn’t in open firmware the way the Zune bug was, people outside of Apple will probably never learn what it was. All we know is that it’s supposedly fixed in iOS 4.2, which will be released just a little too late to have kept this bug hidden.

The bug raises an interesting question: how should an alarm set for, say, 1:30 AM on November 7, 2010 be handled? There are two 1:30s on November 7, one on Daylight Time and one on Standard Time. Which one should the clock honor?

Similarly, if you had a repeating alarm set for 2:30 AM every Sunday, what should it do on March 13, 2011, when DST starts up again? There is no 2:30 AM that day; we go right from 2:00 to 3:00.

N.B., I know the Apple bug isn’t about alarms set for doubled—or nonexistent—times, but I do wonder how alarms should work in these situations. Although I’ve never had to set an alarm for these times, I’m sure there are people who do. When you set a clock manually, you know for sure which time you’re setting it for; it’s not so clear when the time is set by a program you didn’t write.

Now that I’m back home and preparing this for posting—cleaning up typos and adding links—I see that I wrote a post about how the Nano alarm works three years ago. If I’d’ve remembered that last night, I could have had another hour of sleep this morning.

Or maybe I should just use a windup alarm clock and get rid of the ambiguity entirely.

  1. I do think we need a change in nomenclature. How can a time be called Standard when we’re on it for only four months out of the year? ↩

  2. In Chicago, the sun didn’t rise until after 8:00, and that was earlier than in most of the country because we’re on the eastern edge of our time zone. ↩

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