Time zone

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World map with real time zones as mostly frayed south-north stripes of the same color
World map with equally wide time zones between two meridians drawn in black (in the map projection used, spherical triangles become equally wide stripes);
the brightly drawn vertical lines are the reference meridians of the time zones in their respective centers

A time zone is an area on earth that extends between south and north and consists of several states (and parts of larger states) in which the same, state-regulated time , i.e. the same zone time , applies (see adjacent figure).

The time zones are based on 15 ° wide spherical triangles covering the earth's surface between their poles (see figure below), each of which is assigned one of the 24 hours, which is a day long, as the time.

The actual time zones, however, usually deviate greatly from this, because the boundaries of the areas forming them hardly follow meridians . Rather, they have frayed eastern and western borders. In them, the local mean solar time can deviate from the zone time (corresponds to the mean solar time on the reference meridian in the center of the spherical triangle) by more than ideally half an hour. The deviation changes by one (or more) hours if the legal time selected is not that of the appropriate time zone but that of a neighboring (or more distant) time zone. France and Spain , for example, use Central European Time (CET, reference meridian 15 ° East) and have thus "bulged" the Central European time zone far to the west. Due to their geographical location, the Western European time zone with Western European Time (reference meridian 0 °) would actually be more suitable for these countries. In the north-west of Spain (geographical longitude about 9 ° west) the deviation of the Central European zone time from the mean solar time is greatest at about 1 hour 36 minutes.

The actual time zones can also be disjointed; that arises in Asia z. B. from the fact that the legal time valid throughout China extends over five 15 ° wide time zones, while Siberia and southern Asia are regularly divided.

There are also states that do not use any of the 24 zone times related to the Greenwich meridian and form their own time zone (limited in north-south direction):

  • Deviation of half an hour: u. a. Iran, Afghanistan, India, Sri Lanka, parts of Australia,
  • Deviation of a quarter of an hour: u. a. Nepal, Chatham Islands, small areas in Australia.

Time zones, which extend as spherical triangles of equal width from pole to pole of the earth, only exist over the oceans outside the coastal waters of individual states.

With a summer time regulation , the zone time of the east adjoining time zone is used during the summer half-year, e.g. For example, in Central Europe, instead of Central European Time (CET) based on the 15th longitude east of Greenwich, Central European Summer Time (CEST) based on the 30th longitude east of Greenwich , which corresponds to Eastern European Time .

Spherical tacks and actual time zones

Spherical tacks

One of 24 equal spherical tangs extends from pole to pole over 7½  degrees of longitude on either side of its mean longitude. These centers are an integral multiple of 15 ° with respect to the zero meridian of Greenwich . 24 equal spherical tacks as time zones have the following advantages:

  • The time difference to the neighboring time zones is ± 1 hour .
  • The zone time deviates at the zone boundaries only ± ½ hour from the mean solar time .

Actual time zones

An actual time zone is the sum of all states and parts of states with the same selected zone time and areas of the oceans, which are often added as spherical pins or parts thereof.

An actual time zone is first of all characterized by the fact that the western and eastern borders of the states concerned do not follow a longitude. In addition, the close connection to the solar time does not always have priority over traditions, economic considerations or cultural ties to neighboring countries. As a result, the time in a time zone that is adjacent or further away from the sun can be selected as the legal time. An actual time zone with already frayed edges is therefore occasionally additionally offset piece by piece in an east-west direction and is not always a strip that is connected in a north-south direction. Most likely it is a longer part of a spherical taper above the oceans because it is not used here for domestic purposes, but by shipping, aviation and the military (for example by NATO , see DTG ).

Colloquially, the term time zone can only refer to the area of ​​a state, instead of designating this area as belonging to a time zone. Further confusion arises when the terms time zone and zone time are used interchangeably . Some states do not use one of the 24 hours from the grid relating to the Greenwich meridian. They use a time in between and thus create a time zone ending at their southern and northern borders (for example India ).

States with a large east-west extension usually have several times of the day (for example, the United States , Canada and Russia ). They subdivide their area more or less on the basis of spherical objects. Domestic time zones with double or multiple widths can be formed (as in Russia from 2010 to 2014). Or in the state only a single time is used, as in the People's Republic of China , which actually extends over a width of five time zones and was also divided into these five national time zones from 1912 to 1949 . Due to the current situation, China borders on several countries with different other zone times. The largest time jump at a time zone border is 3.5 hours at the border between the PR China and Afghanistan.

The zone times were calculated relative to Greenwich Mean Time . In modern, u. a. According to the legal definition, they are related to Coordinated Universal Time (time zone UTC ± 0 ), from which Greenwich Mean Time can deviate by a maximum of 0.9 seconds (see leap second ). Examples of designations are UTC + 1h (Central European Time CET ) or UTC − 3: 30h (Newfoundland Standard Time). Since the usage of the language is not always clear, a zone time UTC ± x is sometimes also referred to as a time zone.

World map with time zones and zone times

The following map (identical to the first figure at the top) shows the actual time zones created by the state borders and the individual state choice of one or more zone times.

World map with time zones and zone times of the states (possibly not used summer time )

There are more than 24 time zones since

  • individual states chose a less than full hour shift to UTC and
  • at the date line the time zone is also dependent on the choice of date . At the date line (180 ° meridian) there are both the time zones UTC − 12 and UTC + 12. In neighboring time zones, some states chose the date on the other side of the date line (e.g. Tonga , Kiribati , Samoa ), so there are also time zones UTC + 13 and +14.

The legal times (zone times , including standard times or normal times ) of the actual time zones are often not optimal:

  • The national borders extend over more than 15 degrees of longitude , so that the deviation from solar time is greater than ± ½ hour. This applies to larger countries that want to get by with only one or a few zone times (example: only one zone time in China).
  • The reference longitude is not a whole multiple of 15 °, which means that the shift to the time of the adjacent time zones is not ± 1 hour. This often has historical reasons, in that no adjustments were made when the world-wide order of the time zones occurred as a result of the agreement on the prime meridian (examples: Iran , Afghanistan , India , Nepal , Central Australia , Newfoundland ).
  • The reference longitude lies outside the affected area, in the following examples always east of it, so that there is a considerable, for example always positive, deviation from solar time:
Country Zone time /
reference length gr. 		Deviation from / to Longitude from / to
Argentina UTC − 3h: −45 ° +0: ​​48h to +1: 56h −57 ° to −74 °
Iceland UTC ± 0h: ± 0 ° +0: ​​52h to +1: 40h −13 ° to −25 °
Spain UTC + 1h: + 15 ° +0: ​​42h to +1: 38h + 4.5 ° to −9.5 °
France UTC + 1h: + 15 ° +0: ​​26h to +1: 22h + 8.5 ° to −5.5 °
Canary Islands UTC ± 0h: ± 0 ° +0: ​​52h to +1: 14h −13 ° to −18.5 °
Belgium UTC + 1h: + 15 ° +0: ​​34h to +0: 50h + 6.5 ° to + 2.5 °
Netherlands UTC + 1h: + 15 ° +0: ​​30h to +0: 47h + 7.5 ° to + 3.25 °

Origin of the zone times

Geneva before 1886: three clocks for three different local times on a clock tower; left Paris time (−15 min); Middle: Geneva time (± 0min); right: Bernese time (+5 min); the two outer clocks showed the local times used by external railway companies whose trains went to Geneva

Originally, each place had its own time , known as local time, which was based on the daily course of the sun : when the sun in the south reached its highest point above the horizon , it was 12 o'clock. Travelers were guided by the local time of the respective place reached. With the introduction of telegraphy and the construction of longer railway lines , a uniform time specification was required for their operation, which was valid along the entire infrastructure. For this, one often chose the local time of a larger city on the route or the local time of the state capital. Such times, which were uniform in the area of ​​a railway company or in the whole country, were called standard time . Examples are the Berlin, Hamburg, Munich, Prague, Bern and Geneva periods . Telegraphy, introduced in the first half of the 19th century, made it possible to transmit the standard time to all train stations to control the station clocks. The situation was confusing at train stations where several railway lines ended. Geneva was a transit station for a French (Lyon – Lausanne) and terminus for a railway line coming from Bern and had the Paris and Bern times in addition to the local Geneva time . In the middle of the 19th century, a uniform standard time was set in almost all European countries. For this purpose, the local time of a centrally located astronomical observatory was usually chosen , preferably in the respective state capital.

The later systematic zone times were first introduced not by states, but by the North American railway companies in 1883. The railroad lines running across the continent required several standard times. The areas were divided into four time zones with standard times differing by whole hours. The USA and Canada were able to incorporate these time zones and zone times into their state regulations later, because the chosen reference longitudes were already integer multiples of 15 ° with reference to the Greenwich meridian (75 °, 90 °, 105 ° and 120 ° west). The worldwide systematic time zone system was a consequence of the international agreement of the Greenwich meridian as the prime meridian at the International Meridian Conference in Washington the next year (1884). Following the American model, the prime meridian, which is important for cartography, thus served directly as the reference meridian for the Western European time zone and indirectly for all 24 world time zones.

Introduction of the CET in Germany

In the German Reich , the Central European Time (CET) was anchored as legal time with the Time Act ( law concerning the introduction of a uniform time determination ) of 1893 .

Previously, individual times applied in the individual countries, in Bavaria, for example, the Munich time , which was seven minutes (corresponding to about two degrees of longitude) compared to the Berlin time applicable in all of Prussia . The Munich time was also 23 minutes ahead of the then valid time in the Kingdom of Württemberg .

The railways in Germany were also the forerunners of a uniform era. The Prussian state railways used on the territory of the former North German Confederation from the 1880s, the Berlin period as internal operating time, the South German railways but already the later CET. In 1890 the state railways organized in the Association of German Railway Administrations agreed on the CET as their common operating time.

From April 1, 1892, CET became mandatory for the southern states of Baden , Bavaria and Württemberg as a general time in everyday life. With the entry into force of the aforementioned time law, it was valid for the entire territory of the Reich one year later (change on April 1, 1893).

Introduction of CET in Austria

In contrast to most other countries, in the middle of the 19th century Austria did not use the time of the capital Vienna (16 ° east longitude), but Prague time (14.5 ° east longitude). In the railway sector, however, in addition to the Prague, depending on the route, the Lindau, Munich, Budapest or Lviv times were used. Since August 1, 1872 , the Vienna meridian formed the basis for determining the time of train traffic . The Vienna lunchtime was telegraphed from the university observatory to the Vienna train stations , from which the noon signal was telegraphed to the rear railways .

Central European Time (CET) was introduced in the Austrian railway and telegraph service in 1891 and in Vienna by resolution of the municipal council in 1910. There was no statutory regulation as in Germany. For the then Austria, the dual monarchy Austria-Hungary with an extension of about 9th to 23rd degree of longitude, this was a good mean. Since the difference to the time in Prague was less than two minutes, the change was not very great, at least for the capital city dwellers.

Introduction of CET in Switzerland

In Switzerland , when the federal state was founded in 1848, the Bernese time was introduced as a uniform time. From 1859 the investigation took place in the new Neuchâtel observatory , but it was still distributed in local time converted into Bern. At least in some places the local time was used in parallel, for example the Geneva island tower had three clocks around 1880: the right one showed the Bern time, the middle one showed the local time (Bern time −5 minutes) and the left one showed the time of Paris or that of the railway line to Paris (Bern time −20 minutes).

Due to the introduction of the CET in Germany and Austria, the (cantonal) Bernese government council issued a directive on May 18, 1894, according to which “to avoid a confusing duality of time determination [...] this Central European time is also introduced for civil and official life , and all public clocks (church clocks and others) should be advanced by 30 minutes to June 1st ”. The round number 30 came about because Bern is 7.5 ° east longitude. The transfer of the Bernese was followed by the other cantons on the same date.

Zone times today

On land, it is up to the respective states to regulate their time calculation by law. International harmonization is based on cooperation between international and national time institutes and international agreements.

On the oceans and in the airspace, as well as in space travel, the customs and standards of international sea, aviation and space travel apply , which are based on national or supranational obligations, such as nautical time (NATO), which mostly come from the military sector. are regulated.
When traveling east-west or west-east on board a ship, the time change is handled quite arbitrarily and the days on which a change takes place are determined according to the operational requirements on board. As a rule, a maximum of one hour is changed per day. The day on which this happens does not necessarily have to coincide with the crossing of the geographical border between two time zones. The clock is usually adjusted in several steps during the night in order to evenly distribute the resulting additional or reduced work to all guards .

Countries that belong to more than one time zone

The countries listed here either span multiple time zones and / or have overseas holdings in other time zones. Internationally controversial property claims in the Antarctic and deviations caused by summer times are not taken into account .

  • Time zones in Australia : 3 continental zones and 5 zones for outer islands
  • Time zones in Brazil : 4 zones
  • Time zones in Chile: 2 zones in the metropolitan area and 1 zone on islands far offshore
  • Time zones in China : historically (1912–1949) 5 zones, later only 1 zone
  • Time zones in Denmark: 1 zone in the metropolitan area and 3 zones on the autonomous islands
  • Time zones in Ecuador: 1 zone in the metropolitan area and 1 in the Galapagos Islands in the Pacific
  • Time zones in France: 1 zone in the "Métropole" and 11 zones in French overseas territories
  • Time zones in Indonesia: 3 zones
  • Time zones in Canada : 6 zones
  • Time zones in Kazakhstan: 2 zones
  • Time zones in Kiribati: 3 zones
  • Time zones in the Democratic Republic of the Congo (formerly Zaire): 2 zones (UTC + 1 in the west, UTC + 2 in the center and east)
  • Time zones in Mexico : 4 zones
  • Time zones in Mongolia: 2 zones
  • Time zones in New Zealand : 2 zones in the metropolitan area and 3 zones on territories associated with New Zealand
  • Time zones in the Kingdom of the Netherlands: 1 zone in the metropolitan area and 1 zone in Dutch overseas territories
  • Time zones in Portugal: 1 zone in the metropolitan area and 1 zone on remote islands
  • Time zones in Russia : 11 zones
  • Time zones in Spain: 1 zone in the metropolitan area and 1 zone on more distant islands
  • Time zones in South Africa: 1 zone in the metropolitan area and 1 zone in the Prince Edward Islands
  • UK Time Zones: 1 metropolitan zone and 8 UK overseas zones
  • Time zones in the United States : 5 zones on the US mainland and 6 zones outside the mainland area.

The United States, Canada, Russia, Brazil , Mexico , Indonesia , Mongolia , the European Union and Australia have multiple zone times because of their great east-west expansion. The People's Republic of China , on the other hand, only has one (see below).

Countries with specific zone times

Countries with specific zone times whose deviations from UTC or the zone times of neighboring countries are not full hours are e.g. B. Iran (UTC + 3: 30h), Afghanistan (UTC + 4: 30h), India (UTC + 5: 30h), Sri Lanka (UTC + 5: 30h), Nepal (UTC + 5: 45h), Burma (UTC + 6: 30h), in Australia the federal territory of the Northern Territory and the state of South Australia (UTC + 9: 30h), the Cocos Islands (UTC + 6: 30), the Lord Howe Island (UTC + 10: 30) , the Chatham Islands (UTC + 12: 45h), partly French Polynesia (UTC − 9: 30), partly Newfoundland and Labrador (UTC − 3: 30). On December 9, 2007, the clocks in Venezuela (previously UTC − 4h) were also set back by half an hour ( Venezuelan Standard Time VST, UTC − 4: 30h); Since May 1, 2016, UTC − 4h applies again. The reasons for these special cases are mostly the geographical location between two time zones, as well as historical or political nature.

Politically motivated choice of zone times

Most of the countries in the European Union have CET. The USA and Russia, for example, show that even large countries do not see any disadvantage in the use of multiple zone times, and so the three zone times that have been customary up to now relative to solar time are quite suitable for the EU area.

However, France and Spain had already before the European unification efforts - France since the German occupation in 1940, Spain since a Franco decree of 1942 - instead of the more appropriate Western European Time (GMT), which there already deviates considerably from the solar time with normal time, so that z. B. true noon in western Spain does not take place until around 1:40 p.m. Spain had been in the same time zone as neighboring Portugal until 1942, when dictator Franco ordered the time to align with Germany and Italy; there are (as of 2013) efforts there to return to UTC ± 0h. A Spanish parliamentary commission, for example, stated in September 2013 that Spain had (with all the negative side effects) "not been in the correct time zone for more than 71 years", and accordingly recommended the changeover. According to a commissioner, the discrepancy between the sun and the time is the reason why meals in Spain take place much later than the European average: "We eat at noon at one o'clock and at eight in the evening, depending on the position of the sun, but the clock says 3 am and 10 am. "

In the People's Republic of China - whose territory geographically touches five time zones (UTC + 5h to UTC + 9h) - the government decided to use only one time (UTC + 8h) from (around) 1949. This goes well with the capital Beijing and Shanghai . In the westernmost tip of China it is true noon at 3 p.m., in the easternmost tip at 11 a.m.

In Nepal , UTC + 5: 45h applies in order to distinguish itself from its large neighbor India (UTC + 5: 30h).

In 2004, due to a massive energy crisis, it was decided in Cuba to stay in summer time. Until autumn 2006, Cuba had UTC − 4h all year round instead of the geographically "correct" UTC − 5h.

In 1964 Venezuela switched from UT − 4: 30h to UT − 4h. On December 9, 2007, under Hugo Chávez, the geographically more favorable UTC − 4: 30h was reintroduced. This was also politically motivated as a distinction from the customs in the large American neighboring states. Since May 1, 2016, the time UTC − 4h has been in effect again, partly in the hope of being able to reduce power consumption.

In the past, the occupying zone was often imposed on an occupied country. In 1940 , France was converted from GMT to CET under German occupation during World War II. It also introduced CET in the Netherlands . Amsterdam time (also Dutch time ) had applied here since 1909 : originally UT + 0: 19h, since March 17, 1937 rounded to UT + 0: 20h.

In 1942, Japan conquered the Malay Peninsula during the Pacific War . Malaysia was changed from UT + 7: 30h to UT + 9h under Japanese occupation in 1942.

In March 2014, there was a referendum in Crimea on the status of Crimea and its admission to the Russian Federation (see Crimean crisis ). On the night of March 30, 2014, the time previously used in Crimea, UTC + 2h , was adjusted to Moscow time , then UTC + 4h (but now: UTC + 3h) (i.e. the clocks were put forward by two hours).

North Korea announced in early August 2015 that it would introduce its own Pyongyang time with UTC + 8:30 a.m. on the 70th anniversary of its independence from Japanese colonial rule on August 15, 2015 . The change was justified in the North Korean state media as a revision of a relic of the colonial times, quote: "The malicious Japanese imperialists committed unforgivable crimes, such as Korea even taking its standard time." In fact, (entire) Korea had since 1908 UT + 8: 30h and was changed to Japanese time UT + 9h in 1912 (2 years after incorporation into the Japanese Empire from 1910). North Korea retained this time after independence (1945), while South Korea - but only between 1945 and 1961 - switched back to the time before colonization. After the North-South Korea summit meeting at the end of April 2018, North Korea returned to UTC + 9h on May 5, 2018 and is thus back in the same time zone as South Korea.

Summertime

  • Daylight saving time used
  • Daylight saving time no longer used
  • Summertime never used

    • Some countries in the temperate zones set the time an hour forward in spring and back again in autumn. In the German-speaking region, CET (UTC + 1h) (normal time) applies in winter, but Central European summer time (CEST, UTC + 2h) in the summer months .

    The time change has not proven itself everywhere and was not accepted by the government and the population without objection everywhere. In Switzerland, the summer time change was rejected by the people, but was later introduced in order not to create a time island. Summer time has been abolished in some areas of the world. In the recent past, normal time has not been changed back to in Russia (several time zones, 2011), Chile (2015) and Turkey (2016). The previous summer time was declared to be the year-round time, which in fact means a change to the next eastern time zone. In Russia, however, this step was reversed in October 2014; Since then, the normal time has been valid there all year round.

    The two change dates are the same in the EU countries. Other countries sometimes use different dates, so that the time difference between EU countries and other countries can fluctuate by ± 1 hour.

    In the southern hemisphere (e.g. in parts of Australia ) there is a change from summer time to standard time when the northern hemisphere changes from normal time to summer time and vice versa. The time difference between the countries there and Europe fluctuates by ± 2 hours during the year. If the changeover dates are different from those in EU countries, it only changes for a short time by ± 1 hour.

    List of zone times

    In addition to the designation of the zone times in relation to UTC, there are other designations and associated abbreviations that are not binding. The abbreviations can be ambiguous. For example, "ECT" can mean:

    • Eastern Caribbean Time (UTC − 4h)
    • Ecuador Time (UTC − 5h) and
    • European Central Time (UTC + 1h).

    Several watch manufacturers have started using the three-digit IATA airport codes, e.g. B. LAX = Los Angeles International Airport, CA, USA , meaning Pacific Standard Time , which is valid in California in winter.

    Within NATO , times are marked with letters from A to Z in accordance with the DTG .

    Note: The list does not claim to be complete or up-to-date.

    Zone time UTC − 12h to UTC − 9h 30min

    Reload icon - Green.svgUpdate time informationOOjs UI icon help.svg
    UTC − 12h
    (DTG: Yankee)
    Current: 23:55
    08/26/2020     		UTC − 11h
    (DTG: X-Ray)
    Current: 00:55
    08/27/2020     		UTC − 10h
    (DTG: Whiskey)
    Current: 01:55
    08/27/2020     		UTC − 9h 30min
    Current: 02:25
    08/27/2020
    Surname IDLW
    International Date Line West     		HAS
    Hawaii-Aleutian Standard Time
    Summer
    time     		HDT
    Hawaii Daylight Time, UTC − 9h (is no longer used)
    countries

    Regions with an asterisk (*) use daylight saving time.

    Zone time UTC − 9h to UTC − 6h

    UTC − 9h
    (DTG: Victor)
    Current: 02:55
    08/27/2020     		UTC − 8h
    (DTG: Uniform)
    Current: 03:55
    08/27/2020     		UTC − 7h
    (DTG: Tango)
    Current: 04:55
    08/27/2020     		UTC − 6h
    (DTG: Sierra)
    Current: 05:55
    08/27/2020
    Surname AKST
    Alaska Standard Time
    YST
    Yukon Standard Time     		PST
    Pacific Standard Time,
    PT
    Pacific Time     		MST
    Mountain Standard Time     		CST
    Central Standard Time
    Summer
    time     		AKDT
    Alaska Daylight Time
    YDT
    Yukon Daylight Time, UTC − 8h     		PDT
    Pacific Daylight Time, UTC − 7h     		MDT
    Mountain Daylight Time, UTC − 6h     		CDT
    Central Daylight Time, UTC − 5h
    countries

    Regions with an asterisk (*) use daylight saving time.

    Zone time UTC − 5h to UTC − 4h

    UTC − 5h
    (DTG: Romeo)
    Current: 06:55
    08/27/2020     		UTC − 4h
    (DTG: Quebec)
    Current: 07:55
    08/27/2020
    Surname EST
    Eastern Standard Time     		AST
    Atlantic Standard Time
    Summer
    time     		EDT
    Eastern Daylight Time, UTC − 4h     		ADT
    Atlantic Daylight Time, UTC − 3h
    countries

    Countries with an asterisk (*) use daylight saving time and are located in the northern hemisphere .
    Countries with two stars (**) also use daylight saving time, but are in the southern hemisphere .

    Zone time UTC − 3h 30min to UTC − 1h

    UTC − 3h 30min
    Current: 08:25
    08/27/2020     		UTC-3h
    (DTG: Papa)
    Current: 08:55
    08/27/2020     		UTC-2h
    (DTG: Oscar)
    Current: 09:55
    08/27/2020     		UTC − 1h
    (DTG: November)
    Current: 10:55
    August 27th, 2020
    Surname NST
    Newfoundland Standard Time
    Summer
    time     		NDT
    Newfoundland Daylight Time,
    UTC − 2h 30min
    countries

    Countries with an asterisk (*) use daylight saving time and are located in the northern hemisphere .
    Countries with two stars (**) also use daylight saving time, but are in the southern hemisphere .

    Zone time UTC to UTC + 3h

    UTC ± 0h
    (DTG: Zulu)
    Current: 11:55
    August 27, 2020     		UTC + 1h
    (DTG: Alfa)
    Current: 12:55
    27.08.2020     		UTC + 2h
    (DTG: Bravo)
    Current: 13:55
    08/27/2020     		UTC + 3h
    (DTG: Charlie)
    Current: 14:55
    08/27/2020
    Surname WET
    Western European Time,
    German: GMT
    Greenwich Mean Time
    and Z time (mil.) Zulu time
    also: UTC     		CET
    Central European Time
    German: CET
    Central European Time

    (also obsolete MET Middle European Time) (MET)

    		EET
    East European Time
    German: OEZ
    CAT
    Central Africa Time
    SAST
    South Africa Standard Time
    		 BT
    Baghdad Time,
    MSK
    Moscow Time
    EAT
    East African Time
    AST
    Arabian Standard Time
    Summer
    time     		WESZ
    Western European Summer Time,
    WEST / WEDT
    West European Summer / Daylight Time,
    BST
    British Summer Time ( British Standard Time from 1968 to 1971),
    IST
    Irish Standard Time,
    UTC + 1h     		CEST
    Central European Summer Time,
    CEST / CEDT
    Central European Summer / Daylight Time. (obsolete MEST) (MET)
    WAST
    West Africa Summer Time
    UTC + 2h     		EEST / EEDT
    East European Summer / Daylight Time,
    UTC + 3h
    countries

    Countries with an asterisk (*) use daylight saving time and are located in the northern hemisphere .

    (MET)An outdated abbreviation that is still used occasionally today. Today, the term MET actually stands for Middle Eastern Time or the Elapsed Time mission, which NASA uses for its space missions.

    Zone time UTC + 3h 30min to UTC + 5h

    UTC + 3h 30min
    Current: 15:25
    08/27/2020     		UTC + 4h
    (DTG: Delta)
    Current: 15:55
    08/27/2020     		UTC + 4h 30min
    Current: 16:25
    08/27/2020     		UTC + 5h
    (DTG: Echo)
    Current: 16:55
    08/27/2020
    Surname IRT
    Iran Time
    Summer
    time     		IRST
    Iran Summer Time,
    UTC + 4h 30min
    countries

    Regions with an asterisk (*) use daylight saving time.

    Zone time UTC + 5h 30min to UTC + 6h 30min

    UTC + 5h 30min
    Current: 17:25
    08/27/2020     		UTC + 5h 45min
    Current: 17:40
    08/27/2020     		UTC + 6h
    (DTG: Foxtrot)
    Current: 17:55
    08/27/2020     		UTC + 6h 30min
    Current: 18:25
    08/27/2020
    Surname IS
    Indian Standard Time
    Summer
    time
    countries

    Regions with an asterisk (*) use daylight saving time.

    Zone time UTC + 7h to UTC + 9h

    UTC + 7h
    (DTG: Golf)
    Current: 18:55
    08/27/2020     		UTC + 8h
    (DTG: Hotel)
    Current: 19:55
    08/27/2020     		UTC + 9h
    (DTG: India)
    Current: 20:55
    08/27/2020
    Surname ICT
    Indochina Time     		CNST
    China Standard Time     		JST
    Japan / Korea Standard Time
    Summer
    time
    countries

    Countries with an asterisk (*) use daylight saving time and are located in the northern hemisphere .
    Countries with two stars (**) also use daylight saving time, but are in the southern hemisphere .

    Zone time UTC + 9h 30min to UTC + 11h

    UTC + 9h 30min
    Current: 21:25
    08/27/2020     		UTC + 10h
    (DTG: Kilo)
    Current: 21:55
    08/27/2020     		UTC + 10h 30min
    Current: 22:25
    08/27/2020     		UTC + 11h
    (DTG: Lima)
    Current: 22:55
    08/27/2020
    Surname ACST
    Australian Central Standard Time     		AEST
    Australian Eastern Standard Time     		NFT
    Norfolk Time
    Summer
    time     		ACDT
    Australian Central Daylight Time, UTC + 10h 30min     		AEDT
    Australian Eastern Daylight Time, UTC + 11h
    countries

    Countries with an asterisk (*) use daylight saving time and are located in the northern hemisphere .
    Countries with two stars (**) also use daylight saving time, but are in the southern hemisphere .

    Zone time UTC + 12h to UTC + 14h

    UTC + 12h
    (DTG: Mike)
    Current: 23:55
    08/27/2020     		UTC + 12h 45min
    Current: 00:40
    28/08/2020     		UTC + 13h
    Current: 00:55
    08/28/2020     		UTC + 14h
    Current: 01:55
    08/28/2020
    Surname IDLE
    International Date Line East,
    NZST
    New Zealand Standard Time     		No official name available
    Summer
    time     		NZDT
    New Zealand Daylight Time, UTC + 13h     		No official name available UTC + 13h 45min
    countries

    Countries with an asterisk (*) use daylight saving time and are located in the northern hemisphere .
    Countries with two stars (**) also use daylight saving time, but are in the southern hemisphere .

    Historical data

    A widely used source for historical time zone changes (as well as daylight saving time regulations) is The International Atlas by Thomas Shanks and Rique Pottenger and Edward Whitman's World Time Differences . The IATA Aviation Association's Standard Schedules Information Manual, which is updated every six months , also provides information on time zones.

    The Internet Assigned Numbers Authority maintains a globally valid, constantly updated and computer-readable list of all time zones and daylight saving times on its website . For example, so that time spans can be calculated correctly for scientific purposes, even across time zone changes, historical time zone regulations are also specified (e.g. the change in the Netherlands from GMT + 19 min 32.15 s to GMT + 20 min and finally to CET and the change from Crimea to Moscow time).

    See also

    literature

    Basics of the time systems:

    • Friedrich Karl Ginzel : Handbook of mathematical and technical chronology . 3 volumes, Hinrichs, Leipzig 1906–1914. (Until today the German-language standard work par excellence, from the time of the international introduction of the time zone system)
    • Robert Weber: Time Systems . In: Hermann Mucke (Hrsg.): Modern astronomical phenomenology . 20th Sternfreunde Seminar, 1992/93, and 21st Seminar 1994. Planetarium of the City of Vienna and Austrian Astronomical Association, Vienna 1992, p. 33–54 (script on the formulas for calculating time; the standard works by Jean Meeus are more detailed ).
    • PK Seidelmann, B. Guinot, LE Dogget: Time . In: PK Seidelmann, US Naval Observatory (Ed.): Explanatory Supplement to the Astronomical Almanac . University Science Books, Mill Valley, CA 1992, Chapter 2, pp. 39 (English, standard work on astronomical time measurement).
    • Derek Howse: Greenwich Time and the Logitude. Philip Wilson, London 1997, ISBN 0-85667-468-0 .

    Web links

    Commons : Time zones  - collection of images, videos and audio files
    Wiktionary: time zone  - explanations of meanings, word origins, synonyms, translations

    Individual evidence

    1. ↑ Dennis D. McCarthy, P. Kenneth Seidelmann, TIME - From Earth Rotation to Atomic Physics . Wiley-VCH, Weinheim 2009, page 20, section 2.13 Time Zones :
      "A worldwide system of standard time zones, based on increments of 15 degrees in longitude, provides the basis for local civil times that are related loosely to solar time. ..."
    2. ^ McCarthy, Seidelmann:
      "... For political and geographical reasons .... the zone boundaries are set by individual countries and usually follow country, state, or province boundaries."
    3. ↑ See time zones in Russia # Breakdown of time zones 2010–2014 .
    4. ↑ See: Reinhard Dietrich: A railway is opened . In: Der Wormsgau 2017, pp. 111–126 (124).
    5. ↑ Jakob Messerli: “evenly, on time, quickly.” Zuoz 1993, self-published, section 5.6, p. 72
    6. ↑ augsburger-allgemeine.de
    7. ↑ Das Vaterland , August 15, 1872, online
    8. ↑ Austriaforum
    9. ^ Directive of the Bern government council of May 18, 1894, as of June 1; all of Switzerland followed. See Jakob Messerli: Time Systems. In: Historical Lexicon of Switzerland . November 25, 2015 , accessed June 4, 2019 .
    10. ↑ a b c d time zones. Physikalisch-Technische Bundesanstalt , accessed on November 6, 2016 .
    11. ^ Rainer Wandler: TV news should encourage Spaniards to go to sleep earlier. derStandard.at, April 29, 2014, accessed on April 29, 2014 .
    12. ↑ Spain is examining exit from Central European times , ORF.at of September 27, 2013
    13. ↑ Spain considers time zone change to boost productivity. BBC News, September 27, 2013, accessed September 28, 2013 .
    14. ↑ No electricity and no beer in Venezuela , NZZ, April 22, 2016
    15. ^ Robert Harry van Gent: De wettelijke tijdregeling in Nederland. Webpages on the History of Astronomy, March 26, 2009, accessed May 2, 2014 (Dutch).
    16. ↑ Lavrov calls for a new constitution in Kiev , Berliner Zeitung, March 30, 2014.
    17. ↑ New time zone - Kim turned the clock , Frankfurter Allgemeine , August 7, 2015, accessed on April 29, 2018.
    18. ↑ North Korea adjusts time zone to match South Korea , Die Presse, May 4, 2018, accessed May 5, 2018.
    19. ↑ NZZ: Turkey abolishes winter time from September 8, 2016, accessed on September 8, 2016.
    20. ↑ Samoa World Clock Travel Information
    21. ↑ a b Who needs December 30th? - Away with it! , Date jump in Samoa, World Online, accessed December 27, 2011
    22. ↑ Tokelau World Clock Travel Information
    23. ^ Tokelau: Wrong local time for over 100 years
    24. ↑ Thomas Shanks, Rique Pottenger: The International Atlas: World Longitudes & Latitudes, Changes Time and Time Zones . ISBN 978-0-935127-88-1 .
    25. ^ Edward W. Whitman: World Time Differences . 1965.
    26. ^ Standard Schedules Information. In: IATA. Retrieved March 30, 2018 .
    27. ↑ Time Zone Database. In: Internet Assigned Numbers Authority. Retrieved March 25, 2018 .