Pretty sure it was just a typo. @scudsucker lives in C, and he meant what we call 9/11 would be December, 10 there.
Well, it was the tenth for the Romans (decem-) and the 12th for us, so that averages to 11.
Mea culpa, it was not really a typo, just a stupid mistake.
Meh, we all know the months are zero-indexed in C.
Weeks, years, and days too.
Now that this has been done to death, let me hijack this thread to ask the following trivia question. How is that a clock in an Atlantic coastal state can correctly read the same as a clock in a Pacific coastal state?
This text will be blurred The section of western Florida that is west of the continuation of the Georgia/Alabama border is in the central time zone. A strip of eastern Oregon is in the mountain time zone. At 3:00 AM on the first Sunday in November the clock in western Florida will revert to 2:00 AM which is where the clock in eastern Oregon is. An hour later the clock in Oregon will fall back an hour, but for one hour a year they read the same.[/spoiler]
And that is how Columbus discovered America (/s)
My impression is that the “benefit” (such as it is) of changing the clocks is minimal in very high and very low latitudes, and maximal somewhere in the mid-latitudes.
Living at 53 north, we get about 17 hours of daylight in June and about 7 hours in December. No matter what you do to the clocks, we will be either going to work in darkness, or going home in darkness, or both. The effect of any change is short lived, with perhaps a few weeks of “extra” morning daylight in November before we are going to work in the dark again.
Similarly in summer we don’t need the extra hour of daylight in the evening - it stays bright until after 10 pm instead of 9 pm.
Now that I think some more you’re obviously right. No matter how you smoosh the daylight around, there just isn’t enough where you are or farther poleward.
It’s the middle latitudes, say France & Germany or the top 1/3rd of the USA and barely into Canada, where artful rearrangement of the barely-enough winter daylight can produce daylight at one end and at least twilight at the other end of the working / school day.
I traveled to Newfoundland in summer 1988 and remember being baffled by the extra hour of time change. I was proud that I had mastered the half-hour thing and then they gobsmack me with an extra hour out of nowhere. (This was long before the Internet.) I assumed that I must have gotten confused somewhere on the connecting flights out and that the problem was on my end.
Then I got home and forgot about it for 38 years. Until now. Now you have explained it and solved the 38-year mystery. So thank you for that!
Happy to help! This is my best SD moment ever!
This site has some really cool maps of the western hemisphere that are germane to this discussion. It graphs the effects of time zones (and DST) on sunrise and sunset across latitudes and longitudes. The maps were generated in 2016 so any recent changes to DST won’t be reflected.
It makes it clear where the outliers are as well as the issue that @hibernicus raised about 53N and the point about DST only being useful in the ‘middle’ longitudes that @LSLGuy made.
In particular:
- Sunrise on Summer Solstice (#12)
- Sunset on Summer Solstice (#11)
- Hours of daylight on the Summer Solstice (#13)
- Sunrise on Winter Solstice (#16)
- Sunset on Winter Solstice (#17)
- Hours of daylight on the Winter Solstice (#15)
I don’t want to hotlink directly to the map images, but if you click on any map you can quickly navigate through the maps by number.
Near the end, there are maps that include civil twilight, the portion outside of daylight that is still bright enough for outdoor activities. In Chicagoland this is about an hour.
This is also a cool site that lets you choose a location and the solar data.
All trucks in the EU and the UK are fitted with an electronic recording device called a tachograph. This records the start and finish of driving time, whhen the driver does other work such as working in a warehouse, and their rest and break times. All these are strictly regulated.
The device in the cab shows the current time, and if it crosses into a different time zone, the driver can manually adjust it to local time. Internally, however, it kept time on UTC, which is the only way to be sure that elapsed times are accurate and consistent.
The entire US trucking industry nearly crashed a few years ago when those kind of devices were first mandated.
Not due to any timezone confusion among the 4 zones in the continental US, nor any confusion over DST vs. not.
But entirely because of the colossal disconnect between the legal maxes for driving and mins for resting versus actual industry practices. Suddenly we needed 20% more trucks & drivers to haul the same volumes under the same regs. Who knew?!?
Answer: every driver who’d been balancing the books on their back.
“Who knew?”
Some thoughtful design, at least Beta testing. In this case, using GMT and just converting it for display would make sense, My computer servers are all on GMT (but used to be GMT-5) and when were doing Y2K testing they were all those in use plus things like ‘what if Vermont goes 15 minutes ahead’"
The real answer here is the Teamsters are still a thing and looks like we get to keep more money if we choose the lowest bidder.
One inconvenient aspect of using universal GMT especially in the western US would be that the date would change in the late afternoon.
Just a shout-out that @CaveMike’s cites are really great insights as to just how significantly different the annual cycle of long & short days is and how that meshes (badly) with conventional time zones.
Thanks! I was meaning to find this data after the previous SDMB debate on DST. It wasn’t until that thread that I learned how much latitude affected people’s preferences for one or the other.
Looking at the maps I was surprised to see how bad it is for SE Alabama, the FL panhandle, and parts of CA and NM. On the Summer Solstice, even with 14 hours of daylight, sunset is before 8 pm.
DST is an interesting debate because everyone has a strong preference, the preferences are somewhere near 50/50, and as @LSLGuy said it’s completely arbitrary – the amount of sunlight doesn’t change. Meanwhile it’s bad for our health and, most importantly, confusing for the nation’s pets who don’t understand why dinner is one hour later.
An interesting map would be comparing morning twilight twilight versus “normal” get-up and work/school start times. e.g. assume wakeup at 6am year round. Now for each time zone without dst, how much morning light to do you have or not? Same for an assumed getting home time of e.g. 6pm, and evening twilight.
Seeing how that varies by latitude and longitude would really point out that one hour wide time zones are far too crude to ration the marginal amount of winter light available in the northern 1/3rd of the USA and southernmost Canada.
When daylight is in short supply, typical wakeup time and start of twilight need to coincide. And since government, schools, and businesses won’t adjust their opening times, it’s up to us to adjust the clock so sunrise happens at 6am local no matter what latitude and longitude you’re at. Or nearly so. Otherwise you or your kids will be going to school/work in the dark.
So maybe the upper continental USA / Canada have 7 timezones a half-hour apart. While the southern parts stick with the traditional 4. And the northern parts change on different dates optimized to when local sunrise gets more than e.g. 15 minutes away from 6am.
A modest proposal to be sure. Cost of implementation would surely be trivial in this computerized age. 
As to pets …
IANA pet owner. But I think the best plan is to return their feeding methodology to their feral roots as wild animals. There is no schedule. Food will appear in your dish at random times. Get used to it. I’m sure that too will go down a treat with the general public. And their critters. 
I like the 8601 format. I use it often, or something close to it. E.g., right now here near San Francisco CA it is exactly 2026-03-15T0706U. There’s Zulu time, and for us in the CONUS there’s Romeo time (eastern time), Sierra time (central time), Tango time (mountain), and here it is Uniform time (pacific).
Count me as another that wishes we’d stop changing clocks 2x yearly.