The Daily Parker

Politics, Weather, Photography, and the Dog

How far off from sun time are you?

Via the IANA Time Zone Database mailing list, through Randy Olson, comes this map showing the difference between local solar time and what wall clocks show throughout the world:

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.

If you live in the green areas of the map, the sun tends to rise and set earlier than in the red zones. Not coincidentally, the places that set time policy tend to be neutral: London, Washington, Sydney, Beijing, Ottawa...they're all nearly dead-center in their respective zones. The notable exception is Moscow, where time policy goes back and forth and may even change once more this year.

Finally, a commenter on the Reddit MapPorn post where this also appeared points out: "Fun fact: The small Afghan-Chinese border is the largest jump in timezone in the world. (3 and a half hour difference on each side) You'd get jet lag crossing that border."

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