In the summer the suns up at 5 am. But at 5am I am asleep. I could get up earlier but that's pointless since school and work doesn't start until 8.30.
So in stead of having an hour of sunlight before school and work we all change our clocks to have an hour of extra sunlight in the evening in stead, which fits our cultural preference for social activities.
We could also, as you say, change every single sign, post and display of opening hours for every school, business and organisation at the same time to achieve the same effect.
But in the real world changing the clock is simpler.
Some jobs should run every day at 8 am (e.g. torn on the temporary speed limit on front of the school), vs tasks that should actually run every 24h (e.g. feed the bacteria in exact time intervals)
* If it's being run to scrap data from a source that's available at some time, adjust the job if the source changes its time.
* If it's being run "when its dark and no one is around" then it'll run at some part of the dark bit regardless of DST changes.
Have a look at the sunset/sunrise graph for northern parts of the US https://www.timeanddate.com/sun/usa/seattle
In Seattle, without DST, sunrise happens at 4:11am. Because of DST, it's pushed back an hour later to a more reasonable 5:11am.
I am not awake at 4am, I have no use for sunlight at 4am, and I don't want the sun appearing that early. That hour of early sunlight is wasted for me. Plus with DST, the sun sets an hour later, at 9:11pm, a time I am actually awake, and I can actually go outside and use the extra sun.
And, with permanent DST (which is what many people are advocating for), then in winter sunrise is at 9am in Seattle, which is far too late. I do not want to drive to work in the dark, before sunrise. So I want standard time in winter, pushing sunrise an hour earlier to a more reasonable 8am.
In both situations (summer and winter), modifying the time via DST benefits me and gives me better use of sunlight.
If your issue is when work is scheduled, well businesses set their own hours, not the government.
> If your issue is when work is scheduled, well businesses set their own hours, not the government.
Ah, someone who doesn't have kids in school/camp/some random activity yet.
We know how this goes in China (one time zone, no daylight savings time). Coming home from the bar in Beijing with the sun showing up at 4 AM was quaint back then, but I'm definitely glad we have DST in the states.
I think the talk of daylight savings time is a distraction, in the end it is arbitrary what the clock says. As a society we need to negotiate when (in celestial time) we want to do certain activities. For example, there are a lot of studies that school starts to early (relative to sunrise and the average bed time of teenagers). But the school starting time has to be decided politically. And reduced working hours or later start times have to be negotiated by trade unions, politics etc.. That's a lot more messy than just shifting wall time.
Our school schedules are set by weird rules involving when school bus capacity is available. But in general, 9AM is about when school starts (for my son's K-8, its 8AM here for K-5s), or summer camp session starts, or whatever. My schedule is so influenced by my kid these days, it happens to correspond to rush hour, which sucks, because everyone else's schedules are intertwined (so traffic).
I WFH and can definitely set my own work hours. Which is why its 12:30 AM and I still haven't gone to bed yet.
I will fight tooth and nail against attempts to take one hour of daylight from me in the evenings for half of the year.
The bar near me has different opening hours to the library, and that has nothing to do with DST.
In plenty of countries the government decides the opening hours of shops, restaurants and sometimes even offices. Labour laws and nighttime pay are coupled to the hours on the clock. Hours you can make noise is decided by government. Germany has the mid-day resting hour (Mittagsruhe).
Parts of Vermont have traditionally coped with this by having an 8-4 workday instead of 9-5.
But the reality is that Vermont gets only about an hour of daylight outside working hours, depending on local customs. People have extremely strong preferences about how that hour gets split up.
But would behavior change in the long run? Countries like Spain where solar noon differs wildly from clock noon just end up aligning their rituals accordingly (e.g. eating dinner at 9pm).
School starts at 8am everywhere that I know of in northern New England and always has? Does school start at 9am where you live?
And as noted, an 8am start to the working day is long established in certain parts of Vermont and New Hampshire. It has not been "widely unpopular." It's nice to get a few minutes of sunlight and twilight after work in winter.
> I am not awake at 4am, I have no use for sunlight at 4am
Most people aren’t awake at 5am either. Your use for the sun when there is an excess of it that goes well past your bedtime if you get up at 5am is irrelevant.
Under DST, at summer solstice, the sun rises around 5am, giving me 2 hours of wasted sunlight.
Without DST, at summer solstice, the sun rises around 4am, giving me 3 hours of wasted sunlight.
I enjoy having additional hours of sunlight when I am awake, so for me I actually prefer having DST vs without it.
Similarly, in the wintertime, under permanent DST, sunrise is around 9am, and I don't want to drive to work in the dark.
Very easy answer: Because it's already painful twice a year, and that would be making it even worse.
That answer is similar to the one for questions like "why do we have wide time zones that are somewhat inaccurate, rather than setting every clock based on the exact position of that clock?".
While this feels would be a disaster for other reasons like: “How many seconds are in an hour?” -> “Depends, no one knows.” … that’s already the case with our existing leap seconds.
Which we are also in the process of getting rid of.
(This sounds like kicking the can down the road to me; making the maximum discrepancy a minute could take 50-100 years and then you need a leap-minute or equivalent).
If we move to leap-minutes, the Earth will do whatever it does, and it is expected that we'll be able to run on atomic time for a period of decades or perhaps even a century before we need to make another adjustment like we've done with leap seconds in the past.
https://en.wikipedia.org/wiki/Leap_second#Phase-out_and_futu...
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edit: Yeah, I see that your edit covered this adequately. No worries. :)
To that end, I'd like to propose 12 transitions. These should happen on the 16th day of every month, at precisely 05:14:33.
Let's take our seasonality more seriously.
According to https://en.wikipedia.org/wiki/Daylight_saving_time_by_countr... since 2000:
Paraguay 2024
Iran 2022
Jordan 2022
Syria 2022
Fiji 2021
Samoa 2021
Brazil 2019
Morocco 2018
Western Sahara 2018
Namibia 2017
Tonga 2017
Mongolia 2016
Turkey 2016
Azerbaijan 2015
Uruguay 2015
Russia 2014
Libya 2013
Armenia 2011
Belarus 2010
Falklands 2010
Argentina 2009
Bangladesh 2009
Mauritius 2009
Pakistan 2009
Tunisia 2008
Iraq 2007
Guatemala 2006
Honduras 2006
Nicaragua 2006
Sri Lanka 2006
Georgia 2005
Kyrgyzstan 2005
Kazakhstan 2004Queensland Australia is relatively close to the equator, and the length of day does not change dramatically between summer and winter.
DST is intended for places at higher latitudes.
The intent of DST is to normalize variations in the time of sunrise between summer and winter.
Places closer to the equator have minimal variation in the time of sunrise between seasons. They don't need DST.
Higher latitudes have large variation (i.e. Seattle, where the time of sunrise shifts between 4am in summer to 8am in winter), so they benefit from DST or summer/winter hours.
DST is one of the simplest implementations of seasonal hours on a regional scale.
Under permanent DST, the sun rises around 9 AM in December in Seattle. That's far too late. I, and millions of other people, do not want to wake up 2 hours before sunrise and drive to work in the dark.
Under the current system (DST reverts back during winter), sunrise is shifted an hour earlier to around 8AM, which is manageable. I don't have to drive to work in the dark.
It can be dark in Brisbane and still light at my parents house near cape york.
In Sweden, in summer without DST, sunrise in Stockholm would happen ~2:30 AM. In the current system, with DST, sunrise happens around 3:30 AM, an improvement.
In winter, if Sweden kept permanent DST (which is what many advocate for), sunrise in December would happen at around 9:45 AM. In the current system (shifting time back during winter), it happens around 8:45 AM, a more reasonable time.
You realize you're literally proving my point?
> Just set it so noon is actually noon.
Pretty meaningless to advocate for this, then every longitude would have its own timezone, defeating the purpose of timezones.
Did they get several cities to participate?
https://en.wikipedia.org/wiki/Permanent_time_observation_in_...
Possibly another example of the old Chesterton's Fence.
Java and Ruby work differently. Java would simply round the invalid time to the closest valid time IIRC. Ruby would accurately raise the InvalidTime exception. Same behaviors for an ambiguous time.
Chile is actually the country that will cause tricky issue in a system because they adjust DST at midnight... so there is one day a year where its midnight is considered invalid time. If we are building a system that depends on a day's boundary, then we will encounter this nightmarish issue where one of the days must start at 1am instead of midnight.
I really hope DST is going away soon.
Honestly, it was super stressful at the time. And DST that doesn't exist doesn't bother you in the slightest. Every day ends and flows into the next like the last. But the stress of a clock change twice a year doesn't have to happen, it's a choice.
(Sorry about your nightmare. It was easy on the systems I took care of at that time.)
For DST in particular: Even discussions where the participants manage to form something resembling a quorum to stop changing the clocks twice every year somehow manage to unilaterally get sucked into a seemingly-inescapable quagmire of differing opinions, wherein: The decision of whether to use standard time and stick with it or to stick with DST instead becomes an intractable impasse.
Accordingly, nothing ever gets done.
I have every expectation that I will be dead and buried before this issue is resolved.
That 2.6 million people are obese because of a 1h shorter change night in one Sunday a year is an extraordinary claim. I would love to understand how they got to this result.