From winter to summer: Where and when do the clocks change. Local, UTC, Standard Time, and Daylight Savings Time

On July 14 (July 1, according to the old style), 1917, the transition from "winter" to "summer" time was carried out for the first time in Russia.

The expression summer time (summer time or Daylight Saving Time) means an hour ahead of the time adopted in the given time zone. Introduced on summer period in order to save electricity by the governments of a number of countries approximately north of 30° north latitude and south of 30° south latitude.

Switching clock hands to "summer" time is not advisable everywhere. In tropical latitudes (less than 23.5°), daylight hours vary little throughout the year. In polar latitudes (more than 66.33°) there is a polar day and a polar night. The effect of shifting clock hands to "summer" and "winter" time can take place in the latitude range from 30 to 55 °.

Daylight Saving Time in different countries decrease from north to south, amounting to 20-30 weeks in April-May, summer months and September-October (in the northern hemisphere) and about 20 weeks in November-March (in the southern hemisphere). With a significant decrease in the duration of daylight hours, the time is transferred back an hour. The mode of life according to the usual zone time in everyday life is called "winter" time.

For the first time, the idea of ​​\u200b\u200btransferring clocks arose in the 18th century with the American public figure Benjamin Franklin (Benjamin Franklin) in order to save candles for lighting, but was blocked by candle manufacturers.

In 1895, New Zealand entomologist George Vernon Hudson submitted a paper to the Wellington Philosophical Society proposing a two-hour shift to preserve daylight.

The idea of ​​introducing "summer" time found support in most economically developed countries at the beginning of the 20th century, during the period of mass electrification of industry and everyday life. A more rational use of daylight was supposed to reduce the cost of electricity for lighting the premises.

In Great Britain, in 1909, a bill was drawn up on the introduction of "summer" time, which was repeatedly considered in Parliament, but was not adopted until the First World War.

Many states immediately after the end of the war abandoned "summer" time, others repeatedly introduced this time, then abandoned it, and some countries maintained such a time shift throughout the year.

Transfer to "summer" time was introduced in case of crisis situations, for example, during the Second World War (USA, Great Britain), during the oil crisis of 1973-1974 (USA, Germany and other countries).

In Russia, for the first time, this transition was carried out on July 1 (July 14, according to the new style), 1917, when, in accordance with the decree of the Provisional Government, the hands of all clocks in the country were moved one hour ahead.

They were transferred back on December 27, 1917 (January 9, 1918, according to the new style), already in accordance with the decree of the Council of People's Commissars of December 22, 1917 (January 4, 1918, according to the new style).

The practice of switching from "summer" to "winter" time continued until 1924.

Decree of the Council of People's Commissars of the USSR of June 16, 1930 introduced maternity time on the territory of the USSR. Then the clock hands were moved one hour ahead of standard time and after that they were not moved back, and the country all year round began to live and work, one hour ahead of the natural daily cycle. The transfer of clock hands to "summer" time was resumed from April 1, 1981, but already relative to the daylight savings time. Thus, in the country, "summer" time was ahead of standard time for two hours.

In the USSR, and since 1991 in Russia, the introduction of "summer" time was carried out on the night of the last Saturday on the last Sunday of March, and "winter" - on the night of the last Saturday on the last Sunday of September.

In 1996, the period of validity of "summer" time in Russia was "in order to observe a single time regime with other countries. The transition to" winter "time began to be carried out on the last Sunday of October, as in all of Europe.

At the same time, the majority of the Russian population opposed summer time.

July 21, 2014 Russian President Vladimir Putin on Russia's transition from October 26, 2014 to "winter" time. In most constituent entities of the Russian Federation, the clocks were set back an hour, and in the future, the seasonal translation of the hands was not carried out. Five regions of Russia (Udmurtia, Samara Region, Kemerovo Region, Kamchatka Territory and Chukotka Autonomous Okrug) did not switch to "winter" time.

After that, complaints began to come from a number of regions about the lack of sunlight in the evenings. In 2016 Russian authorities approved laws that made it possible to move the clock forward: in the Republic of Altai, Altai and Trans-Baikal Territories, Sakhalin, Astrakhan, Magadan, Tomsk, Ulyanovsk, Novosibirsk and.

At present, there is a consensus among experts and the international community about the significant savings in energy resources during the transition to summer time no.

In 2017, more than 70 countries and territories implemented the transition to "summer" / "winter" time. Of the former Soviet republics, "summer" time was introduced only by Moldova, Ukraine and the three Baltic republics - Latvia, Lithuania and Estonia.

The material was prepared on the basis of information from RIA Novosti and open sources

1. The local time.

Time measured on a given geographic meridian is called local time this meridian. For all places on the same meridian, the hour angle of the vernal equinox (or the Sun, or the mean sun) at any given moment is the same. Therefore, on the entire geographic meridian, local time (stellar or solar) is the same at the same moment.

If the difference between the geographical longitudes of two places is D l, then in a more eastern place the hour angle of any star will be on D l greater than the hour angle of the same luminary in a more westerly location. Therefore, the difference of any local times on two meridians at the same physical moment is always equal to the difference in the longitudes of these meridians, expressed in hours (in units of time):

those. the local mean time of any point on earth is always equal to universal time at that moment plus longitude this paragraph, expressed in hours and considered positive east of Greenwich.

In astronomical calendars, the moments of most phenomena are indicated by universal time. T 0 . The moments of these events in local time T t. are easily determined by formula (1.28).

3. standard time. In everyday life, using both local mean solar time and universal time is inconvenient. First because local systems time counts are in principle the same as geographic meridians, i.e. countless. Therefore, in order to establish the sequence of events or phenomena noted in local time, it is absolutely necessary to know, in addition to the moments, also the difference in longitudes of the meridians on which these events or phenomena took place.

The sequence of events marked according to universal time is easily established, but the large difference between universal time and the local time of meridians, which are far from Greenwich Mean Time, creates inconvenience when using universal time in everyday life.

In 1884, it was proposed belt counting system of average time, the essence of which is as follows. Time is only kept on 24 major geographic meridians located from each other in longitude exactly 15 ° (or 1 h), approximately in the middle of each time zone. Time zones are called plots earth's surface, into which it is conditionally divided by lines extending from its north pole to its south and spaced approximately 7 °.5 from the main meridians. These lines, or boundaries of time zones, follow exactly the geographical meridians only in the open seas and oceans and in uninhabited places on land. For the rest of their length, they go along state, administrative, economic or geographical boundaries, retreating from the corresponding meridian in one direction or another. Time zones are numbered from 0 to 23. Greenwich is taken as the main meridian of the zero zone. The main meridian of the first time zone is located exactly 15 ° east of Greenwich, the second - 30 °, the third - 45 °, etc. until the 23 time zone, the main meridian of which has an east longitude from Greenwich 345 ° (or west longitude 15°).

Standard timeT p is called the local mean solar time, measured on the main meridian of a given time zone. It keeps track of time throughout the territory lying in a given time zone.

Standard time of this zone P is related to universal time by the obvious relationship

T n = T 0 +n h .

(1.29)

It is also quite obvious that the difference between the standard times of two points is an integer number of hours equal to the difference in the numbers of their time zones.

4. Summer time. In order to more rationally distribute electricity used for lighting enterprises and residential premises, and to make the most complete use of daylight in the summer months of the year, in many countries (including our republic), the hour hands of clocks running in standard time are moved forward by 1 hour or half an hour. The so-called summer time. In the fall, the clock is again set to standard time.

DST connection T l any point with its standard time T p and with universal time T 0 is given by the following relations:

(1.30)

Go to winter time takes place on the last Sunday in October
(in 2019 - 27th October- at 04:00 in Kyiv).

A person tends to get up at dawn in order to make the most of daylight hours. This is where the idea of ​​summer and winter time originates, according to which people now live in many countries of the world. Combining waking hours with daylight hours allows you to save electricity consumption: in spring, the hands of clocks running in standard time are set one hour ahead, and in the fall they are set back to standard time.

Divide the whole earth into sentries belts 15 degrees in each, and for the zero line to take the Greenwich meridian - the middle of the zero belt - was proposed by Canadian communications engineer S. Fleming. Inside the belt, time is assumed to be the same everywhere, and at the border, the arrows are moved one hour forward or backward. In 1883, the US government accepted Fleming's idea. And in 1884, at an international conference in Washington, 26 countries signed an agreement on time zones and standard time. Representatives of Russia were also at the conference. They did not like the new account of time for the same reason that Russia stubbornly held on to a mile and a pood: any change seemed to be a “shaking of the foundations” and an impetus to “national fermentation”.

After the October Revolution, on February 8, 1918, zonal division was introduced by a decree of the Council of People's Commissars "in order to establish a uniform count of time with the whole civilized world during the day, which determines on everything the globe the same clock readings in minutes and seconds, and greatly simplifies the registration of the relationship of peoples, social events and most natural phenomena in time.

By a government decree of June 16, 1930, the hands of all clocks in the territory Soviet Union were moved forward by an hour. formed maternity leave time, the introduction of which allowed to save electricity. The period of validity of maternity time was set "until abolition" (lasted until 1981).

By a resolution of the Council of Ministers on April 1, 1981, the hands of the clock were moved forward another hour. Thus, summer time was already two hours ahead of standard time. Within ten years of winter period the hands of the clock were set back an hour compared to summer time, and in the summer they returned to their place again.

In March 1991, maternity time was abolished. The advance two hours ahead has been abolished. We switched to the summer-winter time reference system. Now the standard time is used in winter, and in summer the clock is moved forward 1 hour. This, in brief, is the history of the change in timing.

We measure time by the average solar day, divided into hours, minutes and seconds. Those. by the arithmetic mean of the duration of all true solar days per year (the difference between the duration of the true and average days reaches 15 minutes due to the non-circular orbit of our planet).

Rice. one. Changes in daylight and darkness throughout the year

On fig. 1 shows the change in daylight and darkness during the year for a latitude of 50° (the latitude of Kyiv). The border between light and dark time is considered to be the beginning or end of the so-called civil twilight, that is, the time when the Sun sank 6 ° below the horizon. In the evenings, by this time, lighting should be turned on on the streets of the city. The chart shows sunny true time(true solar time begins and ends at noon, i.e. when the luminary passes through the meridian and stands as high as possible).

The average person gets up at 7 am and goes to bed at 11 pm local time. On the graph, the time of wakefulness of such a person is marked by two horizontal dotted lines. Beginning with Martha he gets up after dawn. By moving the clock forward, he is forced to get up earlier (solid horizontal lines). This is justified by the fact that he will get up during daylight hours and consume less electricity for lighting.

Return to winter time in October does not result in energy savings. As it turned out, this is done solely so that in winter people do not get up much earlier than sunrise. Therefore, the transition to winter time is not justified.

From the point of view of common sense, it is rational to return to standard time, abandon the annual clock change and live with the same countdown, which will be one hour ahead of standard time. Such a rhythm of life, from a biological point of view, is the most favorable for a person.

Since October 26, 2014, the Donetsk and Luhansk People's Republics have switched to a new standard for calculating time and moved the hands in accordance with the third time zone of the international system.
On October 24, 2014, the DPR Supreme Council adopted a resolution “On the transition to Donetsk time”, now Donetsk will have the same time with Moscow and an hour difference with Kyiv. A corresponding resolution was also adopted by the leadership of the LPR.

March 27, 2011 in Russia was the last time the transition to summer time. There will be no more seasonal shifts of the officially accepted time, the Russians will begin to live with a constant shift of +2 hours in relation to standard time. The shift of 2 hours is due to the fact that the so-called "maternity leave" operates on the territory of Russia, which differs from standard time by +1 hour. Daylight Saving Time adds +1 hour to Daylight Saving Time, for a total of +2 hours to Standard Time.

	Daylight Savings Time always took place on the last Sunday of October (on the night from Saturday to Sunday). In 2010, the last daylight saving time was October 31st. On this day, at three o'clock in the morning, the hands were moved back an hour, to two o'clock in the morning. Darkness and light began an hour earlier.
	Daylight Saving Time always carried out on the last Sunday of March (on the night from Saturday to Sunday). In 2011, the last daylight saving time was March 27. On this day, at two o'clock in the morning, the hands were moved forward an hour, at three o'clock in the morning. Darkness and light began an hour later.

what is winter and summer time

Daylight saving time is time that is one hour ahead of normal time in that time zone. By analogy with summer time, standard time is also called winter time.

What is winter and summer time for?

Summer time is introduced in many countries during the summer period in order to save electricity for lighting. However, there is an opinion that the effectiveness of such a measure is insignificant, while the harm to human health caused by the forced displacement of natural biological cycles is great.

when winter and summer time was first introduced

Summer time was first introduced in the UK in 1908. In Russia, the transition to daylight saving time was first implemented in July 1917 and was valid until 1930, when the clock hands were moved one hour ahead of standard time. This time was called "maternity", as it was introduced by the Decree of the Council of People's Commissars on June 16, 1930. Since 1981, summer time has been regularly introduced in the USSR again.

which countries use winter and summer time

Currently, in the northern hemisphere, daylight saving time is used in the USA, Canada, European countries, and throughout Russia. In the southern hemisphere, summer time is used in Australia, New Zealand, Paraguay, Brazil, Chile. The equatorial countries do not use summer time.

When does the changeover to winter and summer time take place?

In Russia and Europe, the transition to daylight saving time is carried out on the night of the last Sunday of March at 2:00 by moving the hour hands 1 hour forward, and the reverse transition is carried out on the night of the last Sunday of October at 3:00 by moving the hands 1 hour back.

In the US and Canada, since 2007, daylight saving time has been on the second Sunday in March at 2:00 am, and back on the last Sunday of October, also at 2:00 am.

offset of winter and summer time relative to standard time

Due to the use of summer time in Russia, Russians live with a shift of +2 hours in relation to standard time. The shift of 2 hours is due to the fact that the so-called "maternity leave" operates on the territory of Russia, which differs from standard time by +1 hour. Daylight Saving Time adds +1 hour to Daylight Saving Time, for a total of +2 hours to Standard Time.