Time zones with a deviation from UTC of a non-integer quantity of hours use the letter of the nearest whole hour-deviated time zone toward UTC, with a star or dagger added on. 'Z' is used to denote UTC, time zones ahead of UTC are designated using letters in the first half of the Roman alphabet, and time zones behind UTC are designated using the second half. The military refers to time zones using single letter designations. 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! Note: The time zone adjustment for a specific location may vary due to the use of daylight saving time. if it is 06:00 UTC on Monday 1 May, then the time in Honolulu is 20:00, Sunday 30 April) if it is 03:00 UTC on Saturday 23 July, then the time in Buenos Aires is 23:00, Friday 22 July) midnight), then the date at the location is one day earlier. Where the adjustment for time zones results in a time before 00:00 (i.e. if it is 21:00 UTC on Wednesday 30 June, then the time in Auckland is 09:00, Thursday 1 July)

if it is 23:00 UTC on Monday 15 March, then the time in Cairo is 01:00, Tuesday 16 March) Where the adjustment for time zones results in a time after midnight, then the date at the location is one day later. if it is 11:00 UTC, then it is 20:00 in Tokyo) if it is 13:00 UTC, then it is 18:30 in New Dehli) if it is 12:00 UTC, then it is 13:00 in Stockholm) if it is 11:00 UTC, then it is 06:00 in New York) if it is 12:00 UTC, then it is 04:00 in Los Angeles) Los Angeles, California, USA: UTC-8 (e.g.The time for a location is given relative to UTC. For the remainder of the year, as in the rest of Europe, local time is UTC+1 (known in the UK as British Summer Time). 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. 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.

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. The reference point for Time Zones is the Prime Meridian ( longitude 000) which passes through the Royal Greenwich Observatory in Greenwich, London, England. Time zones are generally centered on meridians of a longitude that is a multiple of 15º however as the map below shows, the shapes of time zones can be quite irregular because of boundaries of countries.Īll time zones are defined relative to Coordinated Universal Time (UTC). Time zones partially rectified the problem by setting the clocks of a region to the same mean solar time. Formerly, people used apparent solar time, resulting in the time differing slightly from town to town. Time zones are areas of the Earth that follow the same definition of time.

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