Editing Time zone (section)

==Skewing of time zones==
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[[File:Tzdiff-Europe-summer.png|thumb|Difference between sun time and clock time during daylight saving time:
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Ideal time zones, such as nautical time zones, are based on the mean solar time of a particular meridian in the middle of that zone with boundaries located 7.5 degrees east and west of the meridian. In practice, however, many time zone boundaries are drawn much farther to the west, and some countries are located entirely outside their ideal time zones.

For example, even though the Prime Meridian (0°) passes through [[Spain]] and [[France]], they use the mean solar time of 15 degrees east ([[Central European Time]]) rather than 0 degrees (Greenwich Mean Time). France previously used GMT, but was switched to CET (Central European Time) during the [[German occupation of France during World War II|German occupation]] of the country during World War II and did not switch back after the war.<ref>{{cite journal|last=Poulle|first=Yvonne|title=La France à l'heure allemande|journal=Bibliothèque de l'École des Chartes|year=1999|volume=157|issue=2|pages=493–502 |doi-access=free |doi=10.3406/bec.1999.450989}}</ref> Similarly, prior to World War II, the Netherlands observed "Amsterdam Time", which was twenty minutes ahead of Greenwich Mean Time. They were obliged to follow German time during the war, and kept it thereafter. In the mid-1970s the Netherlands, as other European states, began observing daylight saving (summer) time.

One reason to draw time zone boundaries far to the west of their ideal meridians is to allow the more efficient use of afternoon sunlight.<ref>{{cite web|url=http://www.pep.com.cn/200503/ca692073.htm|title=法定时与北京时间|publisher=人民教育出版社|archive-url=https://web.archive.org/web/20061114120456/http://www.pep.com.cn/200503/ca692073.htm|archive-date=November 14, 2006|language=zh}}</ref> Some of these locations also use [[daylight saving time]] (DST), further increasing the difference to local solar time. As a result, in summer, solar noon in the Spanish city of [[Vigo]] occurs at 14:41 clock time. This westernmost area of continental Spain never experiences sunset before 18:00 clock time, even in winter, despite lying 42 degrees north of the equator.<ref>[https://www.timeanddate.com/sun/spain/vigo Vigo, Galicia, Spain – Sunrise, Sunset, and Daylength] {{Webarchive|url=https://web.archive.org/web/20151110174823/http://www.timeanddate.com/sun/spain/vigo |date=November 10, 2015 }}, Timeanddate.com.</ref> Near the summer [[solstice]], Vigo has sunset times after 22:00, similar to those of [[Stockholm]], which is in the same time zone and 17 degrees farther north. Stockholm has much earlier sunrises, though.<ref>[https://www.timeanddate.com/sun/sweden/stockholm Stockholm, Sweden – Sunrise, Sunset, and Daylength] {{Webarchive|url=https://web.archive.org/web/20210209210704/https://www.timeanddate.com/sun/sweden/stockholm |date=February 9, 2021 }}, Timeanddate.com.</ref>

In the United States, the reasons were more historical and business-related. In Midwestern states, like [[Indiana]] and [[Michigan]], those living in [[Indianapolis]] and [[Detroit]] wanted to be on the same time zone as [[New York City|New York]] to simplify communications and transactions.<ref>{{Cite web |first1=Susannah |last1=Dillion |first2=Hugh |last2=Kremer |title=Indiana does not belong in Eastern Time zone |url=https://www.reporter-times.com/story/opinion/2013/04/02/indiana-does-not-belong-in-eastern-time-zone/47166055/ |access-date=2024-06-06 |website=Reporter-Times |language=en-US}}</ref>

A more extreme example is [[Nome, Alaska]], which is at 165°24′W longitude{{snd}}just west of center of the idealized [[Samoa Time Zone]] ([[165th meridian west|165°W]]). Nevertheless, Nome observes [[Alaska Time Zone|Alaska Time]] ([[135th meridian west|135°W]]) with DST so it is slightly more than two hours ahead of the sun in winter and over three in summer.<ref>{{cite web|last=O'Hara|first=Doug|title=Alaska: daylight stealing time|work=Far North Science|url=http://www.farnorthscience.com/2007/03/11/news-from-alaska/alaska-daylight-stealing-time/|date=March 11, 2007|access-date=May 11, 2007|archive-date=September 27, 2007|archive-url=https://web.archive.org/web/20070927094000/http://www.farnorthscience.com/2007/03/11/news-from-alaska/alaska-daylight-stealing-time/|url-status=dead}}</ref>
[[Kotzebue, Alaska]], also near the same meridian but north of the Arctic Circle, has ''two'' sunsets on the same day in early August, one shortly after midnight at the start of the day, and the other shortly before midnight at the end of the day.<ref>{{cite web |url=https://www.upi.com/Archives/1986/08/07/Alaskan-village-to-get-two-sunsets-Friday/5874523771200/ |title=Alaskan village to get two sunsets Friday |archive-url=https://web.archive.org/web/20201020163410/https://www.upi.com/Archives/1986/08/07/Alaskan-village-to-get-two-sunsets-Friday/5874523771200/ |archive-date=October 20, 2020 |url-status=live |website=United Press International |date=August 7, 1986}}</ref>

[[List of extreme points of China|China extends as far west as 73°E]], but all parts of it use [[UTC+08:00]] ([[120th meridian east|120°E]]), so solar "noon" can occur as late as 15:00 in western portions of China such as [[Xinjiang]].<ref>[https://www.timeanddate.com/sun/china/kashgar Kashgar, Xinjiang, China – Sunrise, Sunset, and Daylength] {{Webarchive|url=https://web.archive.org/web/20201108141912/https://www.timeanddate.com/sun/china/kashgar |date=November 8, 2020 }}, Timeanddate.com</ref> The [[Afghanistan-China border]] marks the greatest terrestrial time zone difference on Earth, with a 3.5 hour difference between Afghanistan's UTC+4:30 and China's [[Time in China|UTC+08:00]].

{{Wide image|File:Solar time vs standard time.png|800px|align-cap=center|A visualization of the mismatch between clock time and solar time in different locations. In blue areas, clock time lags behind solar time; in red areas, the reverse is true. The two are synchronized in the white areas.}}