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How much is time wrong around the world?

A few years ago I went to Spain for the first time, and like many I was surprised by how late is dinner. The first night I dined almost alone in a restaurant at 8pm, going away just as people were starting to come in. Of course this can be mostly explained by cultural reasons, but the clearly later-than-usual summer sunsets must also have played a role in shaping the Spanish days.

Solar time vs. standard time

Solar time vs. standard time

At the time I’m writing, near the winter solstice, Madrid’s sunset is around 17:55, more than an hour later than the sunset in, for example, Naples, which is at a similar latitude. The same difference holds at the summer solstice and around the year. Just because it applies to most places I’ve been, a time like that in Naples feels more natural to me, and probably to most non-Spanish people. But is it?

Looking for other regions of the world having the same peculiarity of Spain, I edited a world map from Wikipedia to show the difference between solar and standard time. It turns out, there are many places where the sun rises and sets late in the day, like in Spain, but not a lot where it is very early (highlighted in red and green in the map, respectively). Most of Russia is heavily red, but mostly in zones with very scarce population; the exception is St. Petersburg, with a discrepancy of two hours, but the effect on time is mitigated by the high latitude. The most extreme example of Spain-like time is western China: the difference reaches three hours against solar time. For example, today the sun rises there at 10:15 and sets at 19:45, and solar noon is at 15:01.

So, why do some countries are forced to have such discrepancies? The only way to assign to a place a canonical time which follows our main assumptions is to observe the instant in the day when the Sun is higher in the sky, and call that 12:00. This is not practical for at least two important reasons.

Analemma of the sun

Analemma of the sun

One is that (solar) days do not all have the same length: the modern calendar compensates by letting midday oscillate a bit around the year: for example, midday in Naples goes from 11:47 in early November to 12:17 in early February. The difference between solar noon and clock noon is beautifully explained by an analemma, a picture with an exposure taken every few days at clock noon, showing how the sun moves in the sky not only in height (the north-south) direction due to the different seasons, but also in the east-west direction due precisely to the different lengths of the solar days.

More importantly, each city at a slightly different longitude would have a slightly different time. It seems strange that time systems with such a huge problem had ever been practical, but in the pre-industrial-revolution world, travels were so uncommon and slow that this problem was no more than a minor annoyance. But in today’s hyper connected (physically and virtually) world, it is obviously not an option.

The transition from apparent solar time, where all days have different lengths, to solar mean time, where midday wanders around 12:00, was caused by the proliferation of mechanical clocks in the early 19th century. The change to a time zone system, to solve the second problem, was caused instead by the telegraph and even more by the spreading of railway networks in the second half of that century; it’s not a coincidence that the first country moving to a common time was Great Britain.

Indeed, if we acknowledge that the two problems must be solved, the natural result is the current time zone system. The immediate consequence is that in the western part of the time zone the sun rises and sets later than in the eastern part. Normally, these differences amount to at most half an hour in either direction, but human geography sometime forces greater differences. In Spain’s case, to allow Spain to have the same time as central Europe, the difference can exceed ninety minutes. China instead decided in 1949 to adopt a single time zone, and to place its center in the richer east, forcing the less populated west to have an uncomfortable time. Indeed, though not officially recognized by the government, people in Xinjiang (China’s west-most region) follow a time zone closer to their apparent solar time, shifted by two hours from Beijing time.

Note: luckily, the map was uploaded on Wikipedia as SVG, so it was simply edited with a text editor to add the gradients (using Inkscape to match the objects with their ids). I do not usually like cylindrical projections (my favourite is Robinson‘s, and yes, I like coffee), but this time it made drawing gradients so much easier. And the Miller is a fair enough compromise.

Posted in Statistics.

Tagged with English, Map, Projection, Solar time, Spain, Standard time, Statistics, Time, Time zone.


69 Responses

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  1. Mohad says

    Wow this is really interesting. I was actually thinking about this when reading the Indiana Time Zone wikipedia article. This makes sense of all that. It bothers me so much the way time zones are. I wish people didn’t make such HUGE exceptions. I mean, Russia is a complete mess. Glad I’m from Saint Louis!

  2. Manuela says

    Very good post and map.

    I live in North-West Spain and the official hour seems . During summer time, things get worse. For example in La Coruña, on 20th of June of 2014 noon is going to be at 15:35 !!!!
    Spain used to have the same time than UK, but official time was changed in 1940 after a meeting between Franco and Hitler. And that gesture of submission remains nowadays. Politics also can decide what time is it.
    There is a social movement to change spanish official time, but without massive support.

    By the way, I like how the flag of Iran is painted over Iran. Nice coincidence.

  3. Omar Sarhan says

    Nice article,
    Found the image on Reddit, (http://www.reddit.com/r/MapPorn/comments/1ujwy4/world_map_of_difference_between_solar_time_and/) I think your article has allot more value. I will reblog it on my tumblr.

  4. Víktor Bautista i Roca says

    You should have used as clock time the most used clock time in a given zone. So, for London, colour would not be white, but red, as London uses GMT+1 seven months a year and GMT+0 only five months a year.

  5. David Ma says

    How unfortunate you decided to omit identifying Taiwan as the sovereign state it is.

    Otherwise, a very interesting map.

  6. Stefano says

    Dear David, I’m sorry for any offense, but, as I write in the post, the map is based on http://commons.wikimedia.org/wiki/File:Standard_time_zones_of_the_world_(2012)_-_Pacific_Centered.svg and admittedly I trusted it to be accurate. Thank you for your comment.

  7. Chris Shabsin says

    Have you considered replacing red/green with some other color pairing to allow colorblind people to also read your graphic?

  8. Stefano says

    Very good point, Chris. I received similar feedback from other people. What is the safest pair of color?

  9. Omar Sarhan says

    Colour blind friendlier
    http://i.imgur.com/nARWIVl.jpg

  10. waldir says

    typo: “difference can exceeds”. Also, please upload this back to Wikimedia Commons :D

  11. Than says

    I would imagine that a solution to remove timezones and local specific times, http://en.wikipedia.org/wiki/New_Earth_Time for example, would have been a more sensible solution to the problem of mechanical clocks and fast communication and travel. That way each region would have it’s own schedule, rather than it’s own schedule and it’s own time. I think the time zone solution is only natural as far as there was a progression of synchronizing clocks from further and further apart ignoring the underlying issue of trying to have a noon time everywhere and calling it the same time. Of course now that computers with GPS are relatively cheap, as in cell phones, we could have continuous time zones that actually followed the solar noon. I wonder how that would work in reality…

    In regards to the comment on colorblindness and the chart: the most common colorblindness is “red-green” meaning that those people cannot tell the difference between the two, so choosing a blue as one of the colors would meet the needs of allowing differentiation for the majority of colorblind people. In your defense the gradients go in opposite directions so even in black and white your map would still be illustrative.

  12. Alan Dix says

    Following on from Than’s remark about continuous time based on GPS. This is precisely what I did for the island of Tiree where I live (about 27 minutes later than GMT), with both fixed offset clocks and an HTML5 phone app that tracks your precise time based on longitude.

    http://tireetechwave.org/projects/tiree-time/

  13. Pranay Manocha says

    This is an interesting global visualisation of information that is frequently only assessed at national/regional level. I understand how it was easier to use a cylindrical projection but as the most common use of such a visualisation is inevitably going to be understanding the relation between the proportions of area in the world that are skewed left or right to the true solar time, it would have made more sense to use an equal area projection instead. Still, excellent work. Thanks!

  14. airdrummer says

    “later-than-usual summer sunsets must also have played a role in shaping the Spanish days.”
    i think the spanish culture predates timezones…

  15. Tom says

    Is this with or without daylight savings time?

  16. Stefano says

    Without DST. The effect of DST would be to shift everything towards the red.

  17. blahedo says

    If the ’3′ on Novaya Zemlya (north of Russia) is correct, then its coloration is wrong (should be a lot redder—it’s coloured as if in TZ +4).

    You should re-share your SVG on Wikimedia commons! :)

  18. blahedo says

    Actually, if it were +3 it should be greener. But anyway. :P

  19. Kelly Thomas says

    Time is a human construct. Ask you dog what time it is. (answer:dinner time, it’s always dinner time for a dog but…) Point is they don’t know it’s 2pm. With the advent of mechanical clocks, zones were created to “sync” times with similar numerical values to what had been previously used in solar timekeeping. (i.e. Solar Noon = 12pm) With the advent of GPS and radio communication, time zones solve no problem and in fact, simply serve to create more problems in a global economy. (What time is it where YOU are?) Time Zones should be abolished in North America and the rest of the world would follow.

  20. Eva Daeumling says

    Its very hot in spain. This is why they start to work early, have a SIESTA in the hot time of the day and go to work later again. this is why they have a late supper. The children are also up late and when they are tired, they just lay down somewhere. Eating is a feast and celebrated.
    This could be an answer why they still go for supper late. It is an old habit. And having a SIESTA should be introduced also in the big cities again. :)

  21. Tom says

    Looove your map Stefano,

    The question that occurs is, why is so much of the map red? Why does the very strong tendency to synchronize clocks behind the solar midday exist all over the world?

  22. Stefano says

    It seems that people prefer red places. DST, which is not factored in in this map, shift a place even more towards the red. Russia did exactly that: it made DST the “regular” timezone, so it appears very red. Think about it: if you had 12 hours of light, would you prefer those being between 5am and 5pm (green), or between 7am and 7pm (red)?

  23. Jardinero1 says

    I really like the map and thank the author for his work. I observe high noon ever year, on each solstice, in Houston Texas. The difference between clock and actual is only eleven minutes. The map suggests that the average difference is closer to an hour. Perhaps some field observations are in order, this could be crowd sourced. Or maybe better curve fitting.

  24. Gonzalo Villareal says

    FYI: Iin Argentina, during the summer, the sun goes down at about 20:30 and up at 5 AM, and it goes down at 18 in winter, and up at 8 or 9 AM. Anyway, dinner is always about 21 and 23 hs

  25. Darival says

    Congratulations Stefano, great job!!
    I’m from Spain and to be honest in Spain time is not right, even more in west, it should be the same as UK

  26. Robert Slaven says

    I think what happened was that when time zones were first implemented, everyone knew that you couldn’t just draw straight lines up and down at 7.5°W, 22.5°W, 37.5°W, etc. And I suspect that when it came time for a particular bit near those lines to decide which way to lean, they tended to lean more in favour of the “daylight saving time” direction. Hence the preponderance of red.

  27. Skip says

    Daylight Savings Time makes it worse. I dread its unnatural effect in Indiana each Spring.

  28. Greg Miller says

    I believe there’s a problem with your graphic, and your explanation. You explain that the East-West displacement of the sun in an analemma is what accounts for the differences in the length of day. But what this really is, is the variation of apparent solar time vs mean solar time. This offset is due to the fact that the Earth speeds up and slows down in it’s orbit around the Sun, but maintains a relatively constant rotational speed. E.g. a sundial will be ahead of mean solar time by 15 minutes at one point of the year, and behind mean solar time by 15 minutes 6 months later.

    So I don’t think it’s really possible to show what you want in just one graph. At the very least you’d need two to show the least and greatest. Someone up above had posted such maps for Europe.

  29. Stefano says

    I think we are both right in describing the E-W displacement of the analemma: solar days are almost always not exactly 24 hours long, hence there is a difference between apparent solar time and mean solar time, and this difference varies throughout the year. The map indeed shows the difference with the mean solar time, which is constant (if you don’t count DST). The “Winter” and “Summer” maps linked in a previous comment depict indeed the usage of DST, but are still plotted against the mean solar time.

  30. Lawrence Aggleton says

    Fantastic image and post, thanks. To the point about where people live and what do they prefer, I think there is some interesting sociological hypothesis to be made about this. They’re easier to observe at lower latitudes, but compare Nepal to Singapore. Nepal is highly rural and has a very odd timezone (UTC+5:45) to try and keep the country with solar noon at 12:00. Singapore, by contrast, is completely urban and is shifted to be at 1pm solar noon – in particular its proximity to the equator means it keeps a near constant 7/19 dawn/dusk.

  31. pinkbigmac says

    good reading … i’m going to have a siesta ;)

    greetz from barcelona

  32. Dana Lee Ling says

    Thanks for including the oft overlooked Federated States of Micronesia here in the western Pacific Ocean including even the small outer island atolls. Out here I am keenly aware of the analemma because the days are so close to 12 hours year round here near the equator. In November the earlier arrival of evening makes evening runs hard to get in, harder than in late December. In January and February, the mornings are dark even as the day subtly lengthens, while the evening hours extend.

  33. Snowbunny says

    In Alaska it doesnt matter much, the days are very short over winter ~5 hours, and during the summer we have 3 months of 24/7 daylight. DST just seems pointless (except to maintain our offset with everyone else), with-in a week we gain an hour of daylight at this time of the year (6 mins 50 seconds per day).

  34. Steve Chisnall says

    Needs to factor in daylight saving time and you forgot CWT (Central Western Time) in Australia (a few cities in central-west Oz that, like Nepal, use a quarter-hour offset instead of half-hour) Then there’s daylight saving time which in most places shifts the time a whole hour for summer-time but in one location (Australia’s Lord Howe Island) only shifts HALF an hour when switching from winter-time to summer-time.

  35. Stefano says

    The map doesn’t display anything related to DST (because, well, you’d need two maps for that). As for CWT (or CWST as Wikipedia calls it) in Oz (today I learnt Oz means Australia!), I’ll cite :

    The total population of that area is estimated at 200 people.

    So, that’s kind of below the threshold for this map. But thank you for noticing, it is interesting.

  36. Keith Thomas says

    It’s a work in progress, but I’ve created a website to propose my idea
    for a new system of time that gives the sun the respect it deserves.
    It is a serious effort, but I don’t expect to see it gain traction in
    my lifetime. The essence of the idea is a “smart clock” to give the
    daylight savings effect without biannual clock changes or time zones.
    It can easily be done now that mechanical clocks are no longer the
    latest technology. http://www.localdaylighttime.org/

  37. kalimero says

    Well, I dont know. The natural human instict is wake up with the sun, and in Spain the sun rises at between 6:30-8:00 in the morning (and thats correct). In Poland during summer, for example, you can see the sun at 4:30 but, the sun set is at 18:00; so you wake up too early and you need to use electricity anyway. Sorry, but I dont agree with your opinion.

  38. Gary says

    Very interesting map. I couldn’t help but notice how many of the more populated areas rest in locations that are a much closer match between the solar time vs. manmade time. I wonder if population settle in areas easier if the time matches closer to the natural rhythms?

  39. divisionbyzero0 says

    I like this. Can I copy to a forum?

    I like to live in the green. Java, Indonesia is light green!!

  40. Stefano says

    Sure, go ahead. Thanks!

  41. Jonathan says

    This is absolutely fascinating, how most people in the world live with their clock indicating an earlier time than what actually is. So that they feel like they’re waking up and going to bed later, but in fact they’re not.

    So I guess red areas are great for holidays, and green areas are great for working. I’m sort of lucky, I’m from Switzerland and we’re only 30 minutes early which is fine. But in summer we have this stupid DST, it’s nice to get extra sunlight during holidays evening, sure, but is absolutely terrible when you have to wake up to go to work before 7 AM and it’s still dark. Also we take supper at 6 PM here, long before our Spanish friends, even taking the difference in latitude in account ;)

    In any ways this is fascinating, and thank you very much for your work.

  42. Jorge says

    There are social movements here in Spain that push to go back to GMT (which would be GMT+1 during DST), arguing that moving the clocks one hour backwards would results in a gain of productivity.
    I can agree with setting the time in mainland Spain as per its geographical meridian, but not based on the gain of productivity. A common working time is now 9-14, 15-18. The news in TV start at 21. If the clocks were moved one hour backwards, the working time would become 8-13, 14-17, and the TV news would be at 20, which means at the same solar time than now, so what’s the difference?

    On the other side, in modern times the interaction between different countries is much more important than one century ago, so there is a practical advantage for frequent travellers to have the same time as the nearby countries. For instance, a Spanish businessman dealing with colleagues in France, Germany, etc. is happy to have a common time, as it simplifies ordinary life.

    If the Spanish government decides to move the official time to GMT, it would make sense to make it in coordination with other neighbour countries, such as France, Belgium, Luxembourg, the Netherlands, and of course Andorra and Gibraltar, whose territories fall mainly west of meridian 7.5ºE. But I’m not sure that, in modern times, it would be an advantage to have, for instance, France in GMT and Germany in GMT+1, considering the continuous commercial exchanges between both countries.

    Last, it is important to say that we are assuming that timezones should be one hour width. This is an artificial convention. We could decide to divide the world in 8 time zones, each one separated 3 hours from the next one, instead of 24 main time zones separated 1 hour to each other. In that scenario, all Europe could fall in the same timezone, in the same way that all China share the same official time.

    Just one amendment to Manuela’s post (second one): noon in A Coruña on 20th June 2014 will be at 14:35, and not at 15:35 as you stated. For the rest, a very good post!

  43. CARMEN says

    I live in Spain.. and i think that in summer our shedule is fine because we have a lot of hours of sun and then we can go out at night.
    My family and friends eat at 15 00 and have dinner at 22 then we go out at night and wake up at 12 or so.
    (When you are on holydays)
    If not what we do is sleep a long siesta afterwork or going to the beach to rest and have dinner or go out at night

  44. divisionbyzero0 says

    For lower latitudes like Spain and W. China, the timezone skew effect > daylength effect, so it shapes a different schedule

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