GMT - what time is this? How to calculate time from Greenwich

2024 Author: Harold Hamphrey | [email protected]. Last modified: 2023-12-17 10:06

Until now, in the Windows computer settings, the time zone is set by the abbreviation GMT. What is this and how does it compare with the modern UTC time coordination system? We will talk about this in our article. Not everyone can determine the time at a location relative to Greenwich Mean Time. But we will try to explain this question in popular language. First of all, you need to answer the question: "GMT - what is it?" How does this abbreviation stand for?

British snobbery

In the old days, the time was set at noon. When the sun was at its zenith, that is, it reached its highest point in the visible sky, it was believed that this was twelve o'clock in the afternoon. With the development of international trade, it became necessary to coordinate time into a single system. The point of such a reference was the zero meridian. It passes through the Royal Observatory in Greenwich, near London.

Thus, the abbreviation GMT stands for Greenwich Mean Time. All territories that are west of Greenwich are behind his time, and those that are located to the east are ahead of him. There is another significant meridian on the surface of planet Earth. itdate line. The territory located to the east of it lives (in the truest sense of the word) yesterday. In 1972, the new abbreviation UTC replaced GMT. What time is this? The abbreviation stands for Coordinated Universal Time.

Time Zones

In Russian metrology, the abbreviation SGV is used instead of GMT. What is this? The letters are deciphered as "Geographical Mean Time". But again, we can't get away from Greenwich. After all, the whole world is counting hours from the prime meridian. If you are punctual and accurately determine the time for each point on the globe, you need to know its distance from Greenwich to the west or east. And Coordinated Universal Time (in other words UTC) displays basically noon in certain countries (or parts of them). If GMT is a time that knows no political boundaries, then time zones often extend to an entire state (if it does not extend very much from west to east). Thus, UTC + 0 is not the time at the Greenwich Observatory and at the zero meridian, but throughout the UK and Ireland, as well as Iceland, Portugal, Morocco, etc. But the calculation of hours using the UTS system is carried out according to the same principle as to GMT.

Summertime and wintertime

In countries at high latitudes, daylight hours vary greatly depending on the time of year. Therefore, northern countries often switch to daylight saving time. Residents of these states move the clock forward one hour. It happens inlast Sunday of March. The UK is also on the list of countries that practice the summer clock period. But true noon from April to October is then observed at one o'clock in the afternoon, because GMT does not depend on the season.

Countries lying near the equator, where the duration of daylight hours at any time of the year is approximately equal to twelve hours, do not shift the arrows seasonally. They constantly live in winter (true) time. On this basis, the Russian Federation also decided not to move the hands forward an hour every year. By the way, another country lying in high latitudes refused to switch to daylight saving time. This is Iceland. The island nation lives on Greenwich Mean Time (GMT + 0). Lying approximately on the same meridian, Great Britain and Ireland are in UTC + 0 in winter, and in UTC + 1 in summer.

What UTC and GMT are for

Time is a concept that loves precision. For coordinated actions, dispatching services located in remote points of the Earth need to know what hours, minutes and seconds it is. Broadcasters of different frequencies also have a need for coordinated time. UTC is necessary to establish a certain standard for navigational and scientific purposes. Throughout the nineteenth century, sailors of the British Navy, sailing the oceans, calculated the time according to GMT. Moving west of Greenwich, they took away hours, and to the east, they added. According to this principle, the globe is now divided into time zones. For example, Vladivostok timecorresponds to GMT + 11, Georgian - GMT + 4, Hawaiian-Aleutian - GMT-10, Moscow - GMT + 4, Eastern Standard Time (it is used for New York and the territories adjacent to the Atlantic Ocean of the USA and Canada, as well as in Jamaica, in Panama, Haiti, Bahamas) – GMT-5.