Daylight Saving Time is a huge mess(johndcook.com)
johndcook.com
Daylight Saving Time is a huge mess
http://www.johndcook.com/blog/2011/11/06/dst-is-a-mess/
52 comments
Doesn't "middle-latitude" cover most of the world's population?
Yes, it does. See graph here: http://aidwatchers.com/2010/08/wonderful-graph-on-global-pop...
That's true, but note that China and India, together with 2.6 billion / 7 billion people don't have daylight saving. The former for political, the latter for latitude reasons. Another big country to abolish it recently is Russia.
Just to note that Russia abolished the switching of clocks but didn't really go back to 'standard time'.
> Russia moved its clocks one hour forward to daylight saving time on March 27, 2011. According to the new legislation this is now the country's new standard time. As a result, all of Russia's nine time zones will be permanently two hours ahead of mean solar time, which corresponds to the position of the sun at a given longitude. http://www.timeanddate.com/news/time/russia-dst-law.html
> Russia moved its clocks one hour forward to daylight saving time on March 27, 2011. According to the new legislation this is now the country's new standard time. As a result, all of Russia's nine time zones will be permanently two hours ahead of mean solar time, which corresponds to the position of the sun at a given longitude. http://www.timeanddate.com/news/time/russia-dst-law.html
If you consider the area between the Tropics of Cancer and Capricorn the answer is yes. That's why DST was devised by people who live north of the Tropic of Cancer.
This guy makes absolutely amazing videos on a number of subjects explaining things in really simple terms. He made one explaining Daylight Savings Time here: http://www.youtube.com/watch?v=84aWtseb2-4
His blog with other videos is here: http://blog.cgpgrey.com/
His blog with other videos is here: http://blog.cgpgrey.com/
As a programmer, I hate DST. In fact, I also hate time zones, leap years and horseradish sauce. All are unnecessarily complicated. Now, I don't think the OP's proposal of having everyone go GMT/UTC would work, a simpler solution to measuring this thing we call time has got to exist.
The only thing keeping me from trying to solve this problem with a new standard is this: http://xkcd.com/927/
The only thing keeping me from trying to solve this problem with a new standard is this: http://xkcd.com/927/
Leap years are unnecessarily complicated? No, I think they are exactly as complicated as they should be. And horseradish sauce is both tasty, and quite easy to make.
And not having timezones would be even more complicated.
And not having timezones would be even more complicated.
As a programmer, I know that DST (and time zones and durations and relative times) are all problems to be solved in the presentation layer.
All business logic uses well-engineered, heavily tested third party libraries for time arithmetic. All data storage keeps time zones with timestamps and durations.
Anyone who argues that "I don't need to store timezones because all my dates are UTC" has a long and painfull learning curve ahead of them.
All business logic uses well-engineered, heavily tested third party libraries for time arithmetic. All data storage keeps time zones with timestamps and durations.
Anyone who argues that "I don't need to store timezones because all my dates are UTC" has a long and painfull learning curve ahead of them.
I don't think anyone should set his watch to UTC, only that people use UTC when speaking to people outside their time zone.
Yeah, it's complicated having different times in different places in different seasons. A mess? Perhaps. Useful and rational anyway? Perhaps.
"Time is an illusion. Lunchtime doubly so." - Douglas Adams.
"Time is an illusion. Lunchtime doubly so." - Douglas Adams.
This article promotes a few simplistic ways to think about time. First it says that the "UTC is the time in England minus the day light savings time", which is technically correct, however it's a bad metaphore to give, especially to people in UK. There are many who think "GMT includes daylight sayings time", and so "UTC = Time in England" can make people think that UTC includes daylight savings.
It's also very simplistic to say that a city is on UTC plus/minus X hours, because daylight savings time messes that up. It's much easier to use tzdata format such as "America/Houston", and use a library that uses the tzdata database. Then you never have to worry about when Houston changes from UTC-6 to UTC-5. No point in making work for yourself!
(Also lingustic observance: Seems to be the Americans who say "Daylights savings time" and UK English sayings "Summer Time", anyone else notice this?)
It's also very simplistic to say that a city is on UTC plus/minus X hours, because daylight savings time messes that up. It's much easier to use tzdata format such as "America/Houston", and use a library that uses the tzdata database. Then you never have to worry about when Houston changes from UTC-6 to UTC-5. No point in making work for yourself!
(Also lingustic observance: Seems to be the Americans who say "Daylights savings time" and UK English sayings "Summer Time", anyone else notice this?)
It's Europe-wide in fact. British Summer Time (+1) and Central European Summer Time (+2). Would be interested in the history behind the difference in terminology though.
I'm guessing it has something to do with a lot of people confusing which direction is the "savings" time. As in, did we just enter or leave DST? (I hear people making this mistake or its converse every year.) "Summer" time is harder to make that mistake with.
Yeah, I would not try to explain what UTC is "like". Most people can find the current UTC time somehow. When someone asks me about my timezone, I say "UTC minus six". As John suggests, that's simpler than trying to figure out is that person one or two hours ahead or behind my current time.
Daylight savings and time zones are annoying and DST especially could use some clean up. However, it seems to be a necessary evil. The problem with "Let's just adopt UTC universally" is that now we are pushing the problem of determining whether the person you want to schedule a meeting with is awake when you are from few centralized authorities to each and every individual. Right now, if I tell you that it's 2pm where I am, you can assume that I am awake. If I tell you that it's 6pm UTC, that means nothing until you make the conversion. This conversion gets harder the more UTC is used as the standard. If we still have time zones, then it means you need to look up what timezone I am in, then make the conversion and determine what the local time for me is. If we don't even have time zones, we are stuck with having to look up approximate areas and essentially estimating time zones.
The linked article seems to suggest that I should have written that as 2pm -0400 UTC, which is sort of the best of both worlds. This way your you can make the conversion to your own time much easier. There may be something to this, but I am not sure it is enough to get everyone to agree on proper DST and to get rid of timezones like the ones used in Arizona.
The linked article seems to suggest that I should have written that as 2pm -0400 UTC, which is sort of the best of both worlds. This way your you can make the conversion to your own time much easier. There may be something to this, but I am not sure it is enough to get everyone to agree on proper DST and to get rid of timezones like the ones used in Arizona.
Right now, if you need to schedule meetings during a certain period with geographically separated people, you need to know each person's hours of availability and their time zone so you know how to convert them all to match.. If UTC were adopted universally, you'd need to know each person's hours of availability. You reduce, not increase, the amount of information that needs to be passed around.
For most people, though, hours of availability can be more or less implicit. If I'm scheduling a phone call with a business person who works in an office, I can assume that their availability will probably be highest sometime around 10AM to 5PM in their local time zone. This is less true for hackers, and for self-employed people who don't spend a lot of time interacting with office workers, of course.
> For most people, though, hours of availability can be more or less implicit.
For most people I'm quite sure hours of availability can not be guessed based on what timezone they are in, most people are busy, their windows of availability are much more narrow than 8am-5pm, and surprisingly often they are available outside that range.
For most people I'm quite sure hours of availability can not be guessed based on what timezone they are in, most people are busy, their windows of availability are much more narrow than 8am-5pm, and surprisingly often they are available outside that range.
Even in those cases, the quantity of information you need stays constant. Now, you need their time zone. With UTC everywhere, you need their hours of availability.
There is currently some implicit transfer here, in that if they're in an office in Timbuktu, you can figure out their time zone without asking. But you should still coordinate with them, at which point you can find out their hours.... And I'm sure that in a world where everything is UTC, looking up a particular place's customary business hours will be no more difficult than it currently is to look up a particular place's time zone.
There is currently some implicit transfer here, in that if they're in an office in Timbuktu, you can figure out their time zone without asking. But you should still coordinate with them, at which point you can find out their hours.... And I'm sure that in a world where everything is UTC, looking up a particular place's customary business hours will be no more difficult than it currently is to look up a particular place's time zone.
Personally, I wish the sun came up at exactly 7 am local time every morning plus or minus say, 30 minutes so you could make largish time zones and anything that had to be coordinated cross-time zone was scheduled in UTC.
Yes, this would mean that clocks would adjust by minutes per day, but at least I'd wake up with dawn every morning.
Think how much money we could save in alarm clocks!
Yes, this would mean that clocks would adjust by minutes per day, but at least I'd wake up with dawn every morning.
Think how much money we could save in alarm clocks!
There's a strange upside to this solution - because it's obviously so difficult to "get right" people will probably let other people solve it for them (correctly) instead of writing yet another ad-hoc "mostly correct" implementation.
Last week (when the UK change was) there was the bi-perennial news about if we need it or not, and basically the Scottish don't want it the way we want it, and just because they might soon be independent doesn't change that. http://www.bbc.co.uk/news/magazine-12536056
I like daylight, so I'm a DST fan. In 1973 we had year round DST, But it was abolished the next year. Why you ask? Hey this is the US, to save the children of course. A couple of kids were killed waiting in the dark for their school bus, with a resulting national uproar and a switch back to ST/DST.
The internet company where I work has an interesting solution to the problem. At the fall change they shut down all the servers at 12:50 and restart them at 1:10. Total downtime is 80 minutes. I have always thought that UTC would have been simpler.
Another company made monitoring systems for electrical power distribution, which could not be shut down for the convenience of IT, o it had to deal with a 23 hour day in the spring and a 25 hour day in the fall.
The internet company where I work has an interesting solution to the problem. At the fall change they shut down all the servers at 12:50 and restart them at 1:10. Total downtime is 80 minutes. I have always thought that UTC would have been simpler.
Another company made monitoring systems for electrical power distribution, which could not be shut down for the convenience of IT, o it had to deal with a 23 hour day in the spring and a 25 hour day in the fall.
That's not a solution, but sounds more like a thedailywtf.com posting. DST has not been any problem on most operating systems for a long time now. And for well written applications it should not be any issue either.
Having supported python & rails webapps running on postgres, the biggest problem is not the OS, but the DB and programming language.
Postgres for example, can't change timezones without rebooting. Python & Ruby/Rails both have poor support for handling timezones properly. The proper solution is to of course run the backend in UTC all the time, and just convert to local time when displaying, but if you already have legacy code...
Postgres for example, can't change timezones without rebooting. Python & Ruby/Rails both have poor support for handling timezones properly. The proper solution is to of course run the backend in UTC all the time, and just convert to local time when displaying, but if you already have legacy code...
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> I like daylight, so I'm a DST fan.
Does not follow. DST doesn't increase the available daylight. Maybe your particular habits are helped out by DST, but the above implication doesn't work.
Does not follow. DST doesn't increase the available daylight. Maybe your particular habits are helped out by DST, but the above implication doesn't work.
Sure it does. If you get off of work at 5:00 year-round then DST give you an extra hour of daylight where you can use it. In the winter it gets dark too early to use that hour so it switches back. Winter's non-DST clocks also save energy by allowing people to sleep/heat/drive after sunrise.
One could use that extra daylight without DST by simply doing things in the morning, or having a different work schedule.
Obviously, DST is nice if you have a work schedule that lets you take advantage and you aren't a morning person. But again, that's all dependent on your habits, not simply liking daylight. A morning person with a normal work schedule could very well say that they like daylight and therefore are against DST.
Obviously, DST is nice if you have a work schedule that lets you take advantage and you aren't a morning person. But again, that's all dependent on your habits, not simply liking daylight. A morning person with a normal work schedule could very well say that they like daylight and therefore are against DST.
What you say is true but since it applies to a relatively small percentage of the population the energy savings of year-round DST would be negative. We know this because that is what happened when there was year-round DST, during Jimmy Carter's presidency, as a result of the Arab oil embargo.
From an environmental and energy perspective the current DST calendar is nearly ideal.
From an environmental and energy perspective the current DST calendar is nearly ideal.
It would only take us one generation to just switch over to everyone using UTC in a 24 hour clock and we could get rid of time zones, DST, AM / PM, and all the other time crap built up over the last thousand years around people wanting to always get up at 7 am.
But then again, if the US can't implement the metric system, I have no idea how ~6.5 billion people (those not in GMT right now) would learn that dawn does not always mean 7 am and dusk does not mean 7 pm.
But think of the benefits! Schedule an appointment in CA from NY, and you don't have to explode your brain thinking about time conversions. New show at 20:00! Wait, 8, is that am or pm? No problem!
Just like the metric system! D:
But then again, if the US can't implement the metric system, I have no idea how ~6.5 billion people (those not in GMT right now) would learn that dawn does not always mean 7 am and dusk does not mean 7 pm.
But think of the benefits! Schedule an appointment in CA from NY, and you don't have to explode your brain thinking about time conversions. New show at 20:00! Wait, 8, is that am or pm? No problem!
Just like the metric system! D:
I use http://www.wolframalpha.com/ to do time comparisons.
For instance, if I type in "10pm Taipei" it will tell me the corresponding time here (SF, CA), which is 6am PST.
For instance, if I type in "10pm Taipei" it will tell me the corresponding time here (SF, CA), which is 6am PST.
I use http://www.worldtimebuddy.com/ (discovered it on hn).
It has a really simple and nice interface and visualizes the different time zones very well.
It has a really simple and nice interface and visualizes the different time zones very well.
Thankyouthankyouthankyou I have stupidly lost the link to this site and was unable to find it since. I've also used http://timeanddate.com/worldclock/meetingtime.html, but it's not nearly that usable.
I just tell people to use Swatch Internet Time when setting up meetings. Also known as Biel Mean Time, it has no Daylight Savings Time, and it's the same everywhere in the world.
Example: the time is currently @24 beats.
http://en.wikipedia.org/wiki/Swatch_Internet_Time
Example: the time is currently @24 beats.
http://en.wikipedia.org/wiki/Swatch_Internet_Time
Yeah, sleep disruption in the spring is a bad thing. Sleep disruption in general has been known to cause increased risk of accidents, I don't know if this has been specifically tied to DST or not. If so it wouldn't be exaggerating to say that DST kills people.
Also it's a mess for IT, with software having to be upgraded for timezone database updates. We had an awefull time at my workplace caused by a java timezone update, that had to occur out-of-band vs. the usualy upgrade cycle. DST disposition can vary by county in the US for fucks sake... It's a big mess.
Also it's a mess for IT, with software having to be upgraded for timezone database updates. We had an awefull time at my workplace caused by a java timezone update, that had to occur out-of-band vs. the usualy upgrade cycle. DST disposition can vary by county in the US for fucks sake... It's a big mess.
I find daylight saving useful. It means that instead of an extra hour of daylight from 5am-6am I get an extra hour of daylight between 8pm and 9pm.
Last summer I went to Queensland which doesn't having daylight saving. I woke up at 6am with bright sunlight coming though my window while it was dark by 7pm.
That is the point of daylight saving, move the extra hours of daylight to the evening when they are useful not "wasting" them first thing in the morning when most people can't take advantage of them.
Last summer I went to Queensland which doesn't having daylight saving. I woke up at 6am with bright sunlight coming though my window while it was dark by 7pm.
That is the point of daylight saving, move the extra hours of daylight to the evening when they are useful not "wasting" them first thing in the morning when most people can't take advantage of them.
Was there something in Queensland that prevented you from waking up earlier? If you wanted more time in the morning, why didn't you wake up at 5 o'clock?
I'm okay with people shifting their hours around, but why should I be forced to do the same?
I'm okay with people shifting their hours around, but why should I be forced to do the same?
I didn't want more time in the morning I wanted it in the evening. I was at something from 9-5 and then out in the evening with people.
The way society works is that things happen in the evenings, the number of things to do a 5-7am to take advantage of extra sunlight is a lot more limited.
The way society works is that things happen in the evenings, the number of things to do a 5-7am to take advantage of extra sunlight is a lot more limited.
Because when I'm trying to close a deal with a customer, and I ask when they're free, I'll really impress them by saying, "oh, you're in UTC-5; we're in UTC-6"
How does the article referenced make anyone's life easier? It forces everyone into doing an equation instead of just one person (the host of the meeting)
How does the article referenced make anyone's life easier? It forces everyone into doing an equation instead of just one person (the host of the meeting)
It's a prime example of humanity being stuck in its old ways. During both World Wars, the Germans put Belgium to their timezone, UTC+1. Almost 70 years later, this still hasn't been changed. With as result that in the summer, we're two hours ahead of the correct time.
The Germans did the same with France (which is due south of England, and hence straddles the 0͏° of longitude), and yet it's on CET (central european time).
Lets just have a referendum on abolishing DST. We can certainly do that in California. Arizona does't have it, so we should be able to dump it. Maybe that will be the beginning of the end.
Some light at the end of the tunnel: Russia decided to scrap the whole system this year! I hope they will stick with that absolutely brilliant decision.
Related discussion: http://news.ycombinator.com/item?id=3197827
Thanks OP for getting it right. It's Daylight Saving Time. Not savings. As with labor-saving device, daylight-saving time.
Don't like it, blame a golfer....
The golf course owners were a huge lobby for DST!
Yes, this is the system that I like. I don't give a damn whether or not I live near the equator, in-between, north pole, etc. (for the record, I live in a place where the DST could be considered "useful")
Don't mess with my time.
Alas, hell is other people.
Don't mess with my time.
Alas, hell is other people.
Surprisingly the farther up north you are, there is so much variation that 1 hr doesn't really matter when your days go from 19 hrs long to less than 5 hrs. So Iceland for eg. does not practice Daylight Saving time.
There should be a better reference: http://wwp.greenwichmeantime.com/time-zone/europe/iceland/