Time zone
From Wikipedia, the free encyclopedia.
Time zones are areas of the Earth that have adopted the same local time. Formerly, people used apparent solar time, resulting in the time differing slightly from town to town. As telecommunications improved and with the expansion of the railways this became increasingly awkward. Time zones partially rectified the problem by setting the clocks of a region to the same mean solar time. Time zones are generally centered on meridians of a longitude that is a multiple of 15º thus making neighbouring time zones one hour apart. However, the one hour separation is not universal and, as the map below shows, the shapes of time zones can be quite irregular because they usually follow the boundaries of states, countries or other administrative areas.
All time zones are defined relative to Coordinated Universal Time (UTC). The reference point for Time Zones is the Prime Meridian (longitude 0°) which passes through the Royal Greenwich Observatory in Greenwich, London, England [1]. For this reason the term Greenwich Mean Time (GMT) is still often used (by the BBC, for example, amongst others) to denote the "base time" to which all other time zones are relative. UTC is, nevertheless, the official term for today's atomically measured time as distinct from time determined by astronomical observation as formerly carried out at Greenwich.
GMT (UTC) is, incidentally, local time at Greenwich itself only between 01:00 UTC on the last Sunday in October and 01:00 UTC on the last Sunday in March. For the remainder of the year local time is UTC+1 - known in the UK as British Summer Time (BST).
The time for a location is given relative to UTC. Some examples:
- Los Angeles, California, USA: UTC-8 (e.g. if it is 12:00 UTC, then it is 04:00 in Los Angeles)
- New York, New York, USA: UTC-5 (e.g. if it is 11:00 UTC, then it is 06:00 in New York)
- Stockholm, Sweden: UTC+1 (e.g. if it is 12:00 UTC, then it is 13:00 in Stockholm)
- Mumbai, India: UTC+5.5 (e.g. if it is 13:00 UTC, then it is 18:30 in Mumbai)
- Tokyo, Japan: UTC+9 (e.g. if it is 11:00 UTC, then it is 20:00 in Tokyo)
- Cairo, Egypt: UTC+2 (e.g. if it is 23:00 UTC on Monday 15 March, then the time in Cairo is 01:00, Tuesday 16 March)
- Auckland, New Zealand: UTC+12 (e.g. if it is 21:00 UTC on Wednesday 30 June, then the time in Auckland is 09:00, Thursday 1 July)
- New York, USA: UTC-5 (e.g. if it is 02:00 UTC on Tuesday, then the time in NY is 21:00 on Monday)
- Buenos Aires, Argentina: UTC-4 (e.g. if it is 03:00 UTC on Saturday 23 July, then the time in Buenos Aires is 23:00, Friday 22 July)
- Honolulu, Hawai'i, USA: UTC-10 (e.g. if it is 06:00 UTC on Monday 1 May, then the time in Honolulu is 20:00, Sunday 30 April)
- e.g. New Zealand which is usually UTC+12, observes a one-hour daylight saving time adjustment during the southern hemisphere summer resulting in a local time of UTC+13!
The first time zone in the world was established in the 1840s by the Royal Greenwich Observatory for all of England, Scotland, and Wales. Multiple time zones were first proposed by Sandford Fleming because of the need of railroad companies to have consistent local times between railroad stations. [1] On 18 November 1883, railroads in the United States and Canada became the first to institute multiple time zones when they established four standard continental time zones in North America. This ended a great deal of confusion created by previously having thousands of local times. Although a world-wide system of time zones was proposed at the 1884 International Meridian Conference, it did not accept that proposal, declaring that the time used by individual countries was not within the purview of the conference.
See also: Sidereal time Calculating local time
List of time zones and contained areas
Regions with * observe Daylight Saving Time: add 1 hour in summer.
Note that some regions differ 24 hours in time: they have the same time of the day but differ by a full day. The two extreme time zones even differ 25 hours, hence during one hour a day the date differs 2 days.
A particular day starts earlier in countries with a more positive UTC offset. Thus the first occurence of a date will be in UTC+13 and the last of the same date in UTC-11.
UTC-12
Military designation: Y
UTC-11 (BEST - Bering Standard Time)
Military designation: X
UTC-10 (HST - Hawaii-Aleutian Standard Time Zone)
Military designation: W
- Cook Islands
- French Polynesia
- Society Archipelago including Tahiti,
- Tuamotu Archipelago, and
- Tubuai Islands
- Johnston Atoll
- Tokelau
- United States
- Alaska
- Aleutian Islands (west of 169° West)*
- Hawaii
- Alaska
UTC-9:30
Military designation: V*
UTC-9 (AKST - Alaska Standard Time Zone)
Military designation: V
- French Polynesia
- Gambier Islands
- United States
- Alaska (most of state)*
UTC-8 (PST - Pacific Standard Time Zone)
Military designation: U
- Canada
- British Columbia (most of province)*,
- Yukon*
- Mexico
- Pitcairn Islands
- United States
- California*,
- Idaho*
- north of the Salmon River (between the Oregon state border and the Idaho County/Lemhi County border), and
- west of the Idaho County/Lemhi County border (between the Salmon River and the Montana state border),
- Nevada*,
- Oregon (most of state, including southern 1/5 of Malheur County)*,
- Washington*
UTC-7 (MST - Mountain Standard Time Zone)
Military designation: T
- Canada
- Alberta*,
- British Columbia
- eastern (no DST)
- Most of Peace River Regional District except Fort Ware, Beatton River, Pink Mountain, Sikanni Chief, Buckinghorse River and Trutch
- southeastern*
- East Kootenay Regional District (Creston doesn't observe DST),
- Central Kootenay Regional District east of the Kootenai River and parts east of Kootenay Lake that are south of and including Riondel and
- Columbia-Shuswap Regional District east of the Selkirk Mountains,
- eastern (no DST)
- Northwest Territories*,
- Nunavut*
- west of 102° West, and
- entire Kitikmeot Region,
- Saskatchewan*
- Lloydminster, and
- surrounding area
- Mexico
- Baja California Sur*,
- Chihuahua*,
- Nayarit*,
- Sinaloa*,
- Sonora
- United States
- Arizona (Navajo Nation does observe DST),
- Colorado*,
- Idaho*
- south of the Salmon River (between the Oregon state border and the Idaho County/Lemhi County border), and
- east of the Idaho County/Lemhi County border (between the Salmon River and the Montana state border),
- Kansas*
- Montana*,
- Nebraska (western)*,
- New Mexico*,
- North Dakota (southwestern)*,
- Oregon
- northern 4/5 of Malheur County*,
- South Dakota (western)*,
- Texas*
- El Paso County,
- Hudspeth County, and
- northwestern Culberson County,
- Utah*,
- Wyoming*
UTC-6 (CST - Central Standard Time Zone)
Military designation: S
- Belize
- Canada
- Manitoba*,
- Nunavut
- between 85° West and 102° West (except eastern Kitikmeot Region and western Southampton Island)*,
- Ontario*
- west of 90° West (except Atikokan area, New Osnaburgh and Pickle Lake area, and Shebandowan and Upsala area), and
- Big Trout Lake area east of 90° West,
- Saskatchewan (most of province), except
- Creighton and Denare Beach area, which does observe DST
- Chile
- Costa Rica
- Ecuador
- El Salvador
- Guatemala
- Honduras
- Mexico*
- all other states not already mentioned, plus
- Distrito Federal
- Nicaragua
- United States
- Alabama*,
- Arkansas*,
- Florida
- west of the Apalachicola River, except for those portions of Franklin County and Gulf County south of the Intracoastal Waterway*,
- Illinois*,
- Indiana*
- northwestern
- southwestern
- Iowa*,
- Kansas (most of state)*,
- Kentucky (western)*,
- Louisiana*,
- Michigan*
- Minnesota*,
- Mississippi*,
- Missouri*,
- Nebraska (central and eastern)*,
- North Dakota (most of state)*,
- Oklahoma*,
- South Dakota (eastern)*,
- Tennessee (central and western)*,
- Texas (most of state)*,
- Wisconsin*
UTC-5 (EST - Eastern Standard Time Zone)
Military designation: R
- Bahamas*
- Brazil
- Canada
- Cayman Islands
- Colombia
- Cuba*
- Ecuador
- Haiti
- Jamaica
- Panama
- Peru
- Turks and Caicos Islands*
- United States
- Connecticut*,
- Delaware*,
- District of Columbia*,
- Florida (most of state)*,
- Georgia*,
- Indiana (most of state), except
- Clark County,
- Dearborn County,
- Floyd County,
- Harrison County, and
- Ohio County, which do unofficially observe DST,
- Kentucky (eastern)*,
- Maine*,
- Maryland*,
- Massachusetts*,
- Michigan (most of state)*,
- New Hampshire*,
- New Jersey*,
- New York*,
- North Carolina*,
- Ohio*,
- Pennsylvania*,
- Rhode Island*,
- South Carolina*,
- Tennessee (eastern)*,
- Vermont*,
- Virginia*,
- West Virginia*
UTC-4 (AST - Atlantic Standard Time)
Military designation: Q
- Anguilla
- Antigua and Barbuda
- Aruba
- Barbados
- Bermuda*
- Bolivia
- Brazil
- Amazonas (all but southwestern tip),
- Mato Grosso*,
- Mato Grosso do Sul*,
- Para (western),
- Rondonia,
- Roraima
- Canada
- Labrador (all but southeastern tip)*,
- New Brunswick*,
- Nova Scotia*,
- Prince Edward Island*,
- Quebec (east of the Natashquan River)
- Chile*
- Dominica
- Dominican Republic
- Falkland Islands*
- Greenland
- northwestern
- Pituffik area* (observes United States DST rules)
- northwestern
- Grenada
- Guadeloupe
- Guyana
- Martinique
- Montserrat
- Netherlands Antilles
- Paraguay*
- Puerto Rico
- Saint Kitts and Nevis
- Saint Lucia
- Saint Vincent and the Grenadines
- Trinidad and Tobago
- Venezuela
- Virgin Islands
UTC-3:30 (NST - Newfoundland Standard Time)
Military designation: P*
- Canada
- Labrador (southeastern)*,
- Newfoundland*
UTC-3
Military designation: P
- Argentina
- Brazil
- Alagoas,
- Amapa,
- Bahia*,
- Ceara,
- Distrito Federal*,
- Espirito Santo*,
- Goias*,
- Maranhao,
- Minas Gerais*,
- Para (eastern),
- Paraiba, Parana*,
- Pernambuco, Piaui,
- Rio de Janeiro*,
- Rio Grande do Norte,
- Rio Grande do Sul*,
- Santa Catarina*,
- Sao Paulo*,
- Sergipe,
- Tocantins*)
- French Guiana
- Greenland (most of island)* (observes European Union DST rules)
- Saint-Pierre and Miquelon*
- Suriname
- Uruguay
UTC-2
Military designation: O
UTC-1
Military designation: N
- Cape Verde
- Greenland
- eastern* (observes European Union DST rules)
- Ittoqqortoormiit, and
- surrounding area
- eastern* (observes European Union DST rules)
- Portugal
UTC (WET - West European Time)
Military designation: Z
- Antarctica
- Burkina Faso
- Cote d'Ivoire
- Faroe Islands*
- The Gambia
- Ghana
- Greenland
- northeastern
- Danmarkshavn, and
- surrounding area
- northeastern
- Guinea
- Guinea-Bissau
- Iceland
- Ireland*
- Liberia
- Mali
- Mauritania
- Morocco
- Portugal*
- Saint Helena
- Sao Tome and Principe
- Senegal
- Sierra Leone
- Spain
- Togo
- United Kingdom*
UTC+1 (CET - Central European Time)
Military designation: A
- Albania*
- Algeria
- Andorra*
- Angola
- Austria*
- Belgium*
- Benin
- Bosnia and Herzegovina*
- Cameroon
- Central African Republic
- Chad
- Congo, Republic of the
- Congo, Democratic Republic of the (Kinshasa, Bandundu, Bas-Zaire, Equateur)
- Croatia*
- Czech Republic*
- Denmark*
- Equatorial Guinea
- Republic of Macedonia*
- France*
- Gabon
- Germany*
- Gibraltar*
- Hungary*
- Italy*
- Liechtenstein*
- Luxembourg*
- Malta*
- Monaco*
- Montenegro*
- Namibia*
- Netherlands*
- Niger
- Nigeria
- Norway*
- Poland*
- San Marino*
- Serbia*
- Slovakia*
- Slovenia*
- Spain* (except Canary Islands)
- Svalbard and Jan Mayen*
- Sweden*
- Switzerland*
- Tunisia
UTC+2 (EET - East European Time)
Military designation: B
- Belarus*
- Botswana
- Bulgaria*
- Burundi
- Congo, Democratic Republic of the (Kasai Occidental, Kasai Oriental, Haut-Zaire, Katanga)
- Cyprus*
- Egypt*
- Estonia*
- Finland*
- Gaza Strip*
- Greece*
- Israel*
- Jordan*
- Latvia*
- Lebanon*
- Lesotho
- Libya
- Lithuania*
- Malawi
- Moldova*
- Mozambique
- Romania*
- Russia (Zone 1*, including Kaliningrad)
- Rwanda
- South Africa
- Swaziland
- Syria*
- Turkey*
- Ukraine*
- West Bank*
- Zambia
- Zimbabwe
UTC+3 (MSK - Moscow Time)
Military designation: C
- Bahrain
- Comoros
- Djibouti
- Eritrea
- Ethiopia
- Iraq*
- Kenya
- Kuwait
- Madagascar
- Mayotte
- Qatar
- Russia (Zone 2*, including Moscow and St. Petersburg; this time zone applies also for railways throughout Russia)
- Saudi Arabia
- Somalia
- Sudan
- Tanzania
- Uganda
- Yemen
UTC+3:30
Military designation: C*
- Iran*
UTC+4
Military designation: D
- Armenia*
- Azerbaijan*
- Georgia*
- Kazakhstan (Western)*
- Mauritius
- Oman
- Reunion
- Russia (Zone 3*)
- Seychelles
- United Arab Emirates
UTC+4:30
Military designation: D*
UTC+5
Military designation: E
- Kazakhstan (Central)*
- Kyrgyzstan*
- Maldives
- Pakistan
- Russia (Zone 4*, including Ekaterinburg and Perm)
- Tajikistan
- Turkmenistan
- Uzbekistan
UTC+5:30 (IST - Indian Standard Time)
Military designation: E*
UTC+5:45
Military designation: E†
UTC+6
Military designation: F
- Bangladesh
- Bhutan
- Kazakhstan (Eastern)*
- Russia (Zone 5*, including Novosibirsk and Omsk)
- Sri Lanka
UTC+6:30
Military designation: F*
UTC+7
Military designation: G
UTC+8 (AWST - Australian Western Standard Time)
Military designation: H
- Australia
- Brunei
- Mainland China
- Hong Kong
- Indonesia (Central)
- Macau
- Malaysia
- Mongolia*
- Philippines
- Russia (Zone 7*)
- Singapore
- Taiwan
UTC+9
Military designation: I
- East Timor
- Indonesia (Eastern)
- Japan (JST - Japan Standard Time)
- North Korea
- South Korea (KST - Korea standard time)
- Palau
- Russia (Zone 8*, including Yakutsk)
UTC+9:30 (ACST - Australian Central Standard Time)
Military designation: I*
UTC+10 (AEST - Australian Eastern Standard Time)
Military designation: K
The United States has officially designated this time zone Chamorro Standard Time.
- Australia
- Australian Capital Territory*,
- New South Wales* (except Broken Hill, which observes South Australia time),
- Queensland,
- Tasmania*,
- Victoria*
- Guam
- Federated States of Micronesia
- Northern Mariana Islands
- Papua New Guinea
- Russia (Zone 9*, including Vladivostok)
UTC+10:30
Military designation: K*
- Australia
- New South Wales
- Lord Howe Island* (DST only 0:30)
- New South Wales
UTC+11
Military designation: L
UTC+11:30
Military designation: L*
UTC+12
Military designation: M
- Fiji
- Kiribati
- Marshall Islands
- Nauru
- New Zealand (Aotearoa)*
- Russia (Zone 11*)
- Tuvalu
- Wake Island
- Wallis and Futuna
UTC+12:45
Military designation: M*
UTC+13
Military designation: M†
UTC+14
Military designation: M‡
See also
External links
- World Time Server
- A Solution for Managing Time Zones, and Dates in International Internet Systems
- The tz database provides specific information on the beginning and ending dates of daylight saving time for each zone and tracks time zones over the years.
- Picture of Indiana time zone exceptions.
