How to calculate standard time. Learning to convert solar time to local time

Conversations on the topic of summer, winter, zone, local, astronomical time prompted me to write this post. I'll tell you and show you how to calculate local time. You will learn what standard time is. There will be a little theory and history here. And there will be no medicine and physiology, and I will also leave aside political and economic views on this issue. I am not a doctor, not an economist, and certainly not a politician, I am a navigator.
Therefore, one of the sciences necessary for navigation even in our time - nautical astronomy - is well known to me.
Nautical astronomy allows you to control the position of a ship using observations of celestial bodies. The celestial bodies are constantly moving, and in order to determine their place at a given moment, it is necessary to know the laws of their movement, studied in astronomy. The same applies to artificial Earth satellites. Nautical astronomy, in addition, provides information about the service of time and various phenomena occurring on Earth (sunrises/sunsets, illumination, eclipses, etc.) and in the Universe.
The main problems solved by nautical astronomy are:
- determination of a place in the sea based on observations of luminaries;
- determination of corrections for directional instruments (compasses);
- providing time service.
Auxiliary tasks:
- determination of illumination;
- culmination of luminaries, etc.

Now we come to the topic of time. It is clear that humanity has accepted one day as a unit of time - during this time the Earth makes one revolution around its axis, or the period of time from sunrise to sunrise. Then this period of time was divided by 24 and we got 1 hour. Since one revolution is 360 degrees, we get that 1 hour is 15 degrees of rotation of the Earth around its axis (apparent movement of the Sun), and one degree of movement of the Sun (rotation of the Earth) is 4 minutes of time accepted by earthlings.
And let’s not complicate the task with the knowledge that:
- the Earth's rotation is slowing down by 0.00023 seconds per century;
- random abrupt changes in the speed of rotation of the Earth (several of them were noted, one in 1920 at 0.000000045 s);
- the value of true solar days during the year varies on average by 59.14 s;
- a year is not 365 days, but 365.2422 days.

Therefore, to discuss the topic of sleep-rest-work and changing clocks, we will not talk about true solar and sidereal times (astronomical). We will only operate with the average solar time accepted for calculating time on Earth. When the length of a day is calculated not from one day, but on average over 1 year.
Local time - time of the observer on a given meridian, and since There are countless meridians, and there are countless local times. But all observers on the same meridian have the same local time.
Greenwich time is the local time of an observer standing on the Greenwich meridian.
Because The Greenwich meridian is taken as the origin of longitude on the globe, then local time differs from Greenwich exactly by the longitude of the place, converted from an angular measure to a time one at the rate of 360 degrees = 24 hours.
There is a saying:
"Longitude west, Greenwich time best.
Longitude east, Greenwich time least".
Which, loosely translated, means that with eastern longitude you have more time than Greenwich, and with western longitude you have less time than Greenwich.

Now we know that Greenwich time is taken as the reference point, but local time is inconvenient for everyday life.
Therefore, a single time was adopted for an entire region or country (local observatory, ruler’s palace, etc.). But...
With this approach, inconveniences arise - the difference with the time of another region or country could contain fractional parts of hours and even minutes. The development of civilization and communication between peoples required streamlining the calculation of time.

At the astronomical congress of 1884, a system of standard times was proposed and gradually adopted in almost all countries of the world. In the zone time system, time is kept on 24 central meridians of the Earth, separated from each other by 15 degrees of longitude, so that in neighboring zones the time differs by 1 hour. Standard time extends to 7.5 degrees of longitude on either side of the central meridians.
Standard Time Zone time is the average local time of the central meridian of a given time zone, accepted throughout the zone.

But there is a small trick - on the 12th central meridian the longitude is 180 degrees, and one part of its belt is in the eastern hemisphere, and the second is in the western. The time on the clocks of residents of this zone is the same, but the number on the calendar for residents of the eastern and western hemispheres is different and differs by 1 day. The inhabitants of the Western Hemisphere have it only yesterday, compared to us, the inhabitants of the eastern part of the Earth. And this meridian is called the date line.

With such a structure of zones, standard time cannot differ from local time by more than 30 minutes. However, the theoretical boundaries of the belts are observed only in the seas, oceans and sparsely populated areas. In fact, the boundaries of the belts are determined by the governments of countries, taking into account administrative, geographical and economic characteristics.

Maternity time. In order to save electricity on evening lighting, clocks in the USSR were set 1 hour ahead of standard time. Initially, this time was introduced only in the summer (summer time), but by decree in 1931 it was left permanent. That is, maternity time is standard time 1 hour.

Summer time. In a number of countries, moving clocks forward by 1 hour (sometimes by 2 hours) is carried out only for the summer. In the USSR, summer time (1 hour to maternity time or 2 hours to standard time) was introduced in 1980. I won’t describe the further game with time and time zones in our country - everyone knows.
Today our country is divided into time zones like this.

We convert the resulting longitude (in order not to waste time on trifles, we take only an integer number of degrees) into hours and minutes at the rate of 15 degrees - 1 hour, 1 degree - 4 minutes. We make a small assumption that the Sun passes its upper culmination (noon) at about 12.00 local time (in fact - 12.00 plus or minus about 15 minutes).
Now from 12 hours 00 minutes we subtract (for the eastern hemisphere, and for the western hemisphere we add) the resulting longitude value in hours and minutes. We get the Greenwich time of noon at a given meridian (longitude). Next, we add the difference on your watch with Greenwich (UTC, universal) time for the eastern hemisphere (and subtract it if we count the western hemisphere).
Ask: “Where can I find Greenwich Time?” I’ll answer - this is today’s Moscow minus 4 hours (today is February 3, 2013, otherwise we don’t know what will happen with the time tomorrow).

Example: eastern longitude 33 degrees, Moscow time, i.e. Greenwich 4 hours

Convert longitude to hours:
- 33/15=2.2 means 2 hours
- 2,2-2=0,2
- 0.2*60=12 means 12 minutes
- longitude 33 degrees expressed in hours - 2 hours 12 m.

Determining the time of our local noon GMT:
12h00m - 2h12m = 9h48m

Add the clock difference (what is on your hand or next to it) with Greenwich:
9h48m + 4h = 13h 48m.
This is the time of noon according to our watch (which is on your hand or nearby) in a place with a longitude of 33 degrees in the eastern hemisphere (remember - with an accuracy of 30 minutes, because the Sun is not always at its highest culmination at 12.00). For accurate calculations, navigators use astronomical tables.

Now it's standard time. You need to convert the longitude of the place into hours and round to the nearest hour.
For example: longitude 142.9 degrees East.
142,9/15=9,526
This means the 10th Eastern time zone. Those. 10 hours more than Greenwich.

A few words about sunrise. On the Equator, the Sun always rises around 6 am local time and sets at around 6 pm. Further north or south, the time of sunrise and sunset depends on the latitude of the place and the time of year. But on the days of the spring and autumn equinox at all latitudes, the Sun rises and sets, as on the Equator - around 6 and 18 hours local time.
Using the example of St. Petersburg and all places at latitude 60 degrees north. Local time:
March 20 sunrise at 6 a.m. sunset at 6:15 p.m.
June 21 sunrise at 2:36 am sunset at 21:28
September 22 sunrise at 5:45 am sunset at 6:00 pm
December 21, sunrise at 8:50 am, sunset at 14:55

Used: “Nautical Astronomy” by B.I. Krasavtsev (Moscow “Transport” 1986), MAE 2012.

Exact time and determination of geographic longitude.

The sun always illuminates only half of the globe: on one hemisphere it is day, and on the other at this time it is night, respectively, there are always points where it is noon at the moment, and the Sun is at its highest culmination. As the Earth rotates around its axis, noon occurs in those places that lie to the west. The position of the Sun (or stars) in the sky determines local time for any point on the globe. The local time at two points (T1 and T2) differs exactly as much as their geographic longitude differs:

T1-T2 = L1- L2.

It is clear that noon occurs at a given point on the Earth later than at another, exactly as much time as it takes for the planet to rotate through the angle corresponding to the difference in their longitudes. So, for example, in St. Petersburg, which is located 8 ° 45 "west of Moscow, noon occurs 35 minutes later. By determining from observations the local time at a given point and comparing it with the local time of another, the geographic longitude of which is known, you can calculate the geographic longitude of the observation point. It was agreed to count longitude from the prime (zero) meridian passing through the Greenwich Observatory. The local time of this meridian is called universal time (UT).

in other words, the local time of any point is equal to the universal time at that moment plus the longitude of this point from the prime meridian, expressed in hourly units. Accurate calculation of time is complicated by the fact that its previous standard - the Earth's rotation period - turned out to be not entirely reliable. The solar day has long been chosen as one of the basic units of time - the period of time that passes from one upper culmination of the Sun to another. But as the accuracy of astronomical observations increased, it became obvious that the length of the day did not remain constant.

The speed of rotation of our planet changes throughout the year, and in addition, its rotation slows down, albeit very slowly. Therefore, it is clear that the definition of a second as a unit of time constituting 1/86,400 of a day required clarification. You know the modern definition of a second from a physics course. The use of atomic clocks, which are available to precise time services and the state standard of time and frequency, provides an extremely small error in time counting (about 5 10-9 s per day). Precise time signals broadcast over the radio are transmitted precisely from atomic clocks. By receiving these signals and determining local time from observations of the moments of stellar culmination, it is possible to calculate the exact coordinates of any point on the earth's surface. These points serve as reference points for drawing up maps, laying gas pipelines, roads and railways, constructing large facilities and a number of other works.

Precise time signals, along with other means (radio beacons, navigation satellites, etc.) are necessary in aviation and maritime navigation. If we used local time in our daily lives, then as we moved west or east we would have to continuously move the clock hands. The inconveniences arising from this are so obvious that currently almost the entire population of the globe uses standard time. The zone system of counting time was proposed in 1884. According to this system, the entire globe was divided by longitude into 24 time zones (according to the number of hours in a day), each of which occupies approximately 15°. In fact, time is counted according to this system only on 24 main meridians, spaced 15° from each other in longitude. The time on these meridians, which are located approximately in the middle of each time zone, differs by exactly one hour. The local time of the main meridian of a given zone is called standard time. It is used to keep track of time throughout the entire territory belonging to this time zone. Standard time, which is accepted in a particular location, differs from universal time by a number of hours equal to the number of its time zone:

where UT is universal time, and n is the time zone number.

The boundaries of time zones are lines that run from the North Pole of the Earth to the South Pole and are approximately 7.5° from the main meridians. These boundaries do not always run strictly along meridians, but are drawn along the administrative boundaries of regions or other regions so that the same time applies throughout their entire territory. Naturally, for example, Moscow lives according to the time of one (second) time zone. If we formally follow the accepted rule of dividing into time zones, then it would be necessary to draw the border of the zone in such a way that the city would be divided into two unequal parts.

In our country, standard time was introduced on July 1, 1919. Since then, the boundaries of time zones have been repeatedly reviewed and changed. Since January 1992, when clocks in Russia were moved forward one hour, we live according to the so-called maternity time, which was introduced in the USSR back in 1930. At the end of March, the country switches to summer time, the clock hands are moved one more an hour ahead. Daylight saving time is canceled at the end of September, the hands are set back one hour. The days when summer time is introduced and canceled are established annually by government decree. Moscow maternity time, which is shown by clocks not only in Moscow, but also in St. Petersburg and the central regions of Russia, differs from universal time by 3 hours in winter and 4 hours in summer.

A time calculator is needed to find out what time it will be in the place you need.

For example, you want to call your beloved grandfather in Vladivostok to congratulate him on his birthday. You know that the guests will sit down to the festive table at half past seven in the evening, and you want to congratulate him at that very moment.

But by coincidence, you yourself are in the city of Darwin, Australia, and you need to find out what time, Australian time, the birthday celebration will begin.

This is where our calculator comes in handy. To find out the time, you just need to indicate half past six and the date of your birthday in the left column, select Vladivostok there and click on the "=" button between the columns

How to use the time calculator?

On the calculator panel you can see two columns - source And result

Source- this is the date, time and place known to you. Result- the required date and time.

You can set the time and date in the source by simply clicking on the corresponding field.

After setting the date and time, you need to specify the location for which you have set the time. In the birthday example, this would be the city of Vladivostok.

Below the fields for setting the date and time there is an item time is set to- this is a switch. With it, you can indicate whether you specified the time for a specific city or for a time zone. To find out the time of Vladivostok from our example, you can select both the city itself and the time zone of Vladivostok - VLAT.

To switch from indicating a city to indicating a time zone, simply left-click on the switch.

Name is the name of the object for which the time was set. Based on the value of the switch, this could be the name of the city or the name of the time zone.

After setting the date, time and source location, you need to specify which location you are looking for the time for. In our happy birthday example, it's Darwin, Australia. Using a similar switch, you can also specify both the city itself and its time zone - ACST

Once you have set all the values, just click on the " = " between fields, and find out the time you are looking for!

All the buttons of our calculator are labeled, and if you have forgotten the meaning of a particular button, hover your mouse over it. After a second, a hint will appear with its meaning.

Algorithm for solving problems

by definition of standard and local time.

Definition of standard time

Task: Determine the standard time of Magadan if it is 6 o’clock in Moscow.

Actions:

1. Determine what time zone the locations are in

Moscow 2; Magadan 10;

2. Determine how much the time difference is between the points

10 -2 =8 (difference between points in time)

3. Calculate the standard time (determine which point is east and which is west.) Magadan is east, which means there is more time there, therefore, you need to add the time difference to Moscow time. 6 +8 = 14 hours

Answer: Magadan standard time is 14 hours.

Determining local time

Task: Determine the local time in Magadan if it is 6 o'clock in Moscow.

Actions:

1. Determine the geographical longitude of the points

Moscow 37° east; Magadan 151° E;

2. Calculate the difference in degrees between points

151°-37°=114°

3. Calculate the time difference between points

114 x 4 =456:60= 7.6 hours (this is 7 hours 36 minutes because 0.6 hours x 60 minutes = 36 minutes)

4. Determine local time (add Moscow time and time difference.)

6 +7 hours 36 minutes = 13 hours 36 minutes

Answer: Local time in Magadan13 hours 36 minutes

Notes :

0.1 hour – 6 minutes

0.2 hours -12 minutes

0.3 hours -18 minutes etc.

Tasks for determining standard time

The plane took off from Chita (8th time zone) to Murmansk (2nd time zone) at 22:00.

The plane landed in Murmansk at 21:00. How long was the plane in flight?

Solution:

To answer the task you need to determine the time difference in two cities. It is known that the time of each time zone differs by 1 hour. For Chita and Murmansk the difference is

(8 – 2 = 6) 6 hours Knowing that Chita is located east of Murmansk, we conclude that in Chita

time is 6 hours more than in Murmansk. This means the plane took off from Chita when it was (22 – 6 = 16) 16 o’clock in Murmansk, and landed in Murmansk at 21 o’clock. Accordingly, it was in flight for 5 hours.

Tasks:

1. The plane took off from Chita (8th time zone) to Murmansk (2nd time zone) at 15:00 local time. The flight time from Chita to Murmansk is 5 hours. How long will it be in Murmansk when the plane lands? Answer: 14 hours

2. Determine when, Moscow time, you will land in Moscow (2nd time zone)

an airplane that took off from Yekaterinburg (4th time zone) at 11 a.m. local time and was in flight for 2 hours. Answer: 11 a.m.

3. Determine when, Moscow time, you will land in Moscow (2nd time zone)

An airplane that took off from Novosibirsk (5th time zone) at 11 a.m. local time and was in flight for 5 hours. Answer: 13 hours.

4. The plane took off at 9 o’clock from Moscow (2nd time zone) to Yakutsk (8th time zone).

When, local time, will a plane that has been in flight for 5 hours land in Yakutsk?

Answer: 20 hours

5. How much time (including maternity leave) will it be in Krasnoyarsk (6th time zone) if it is midnight in London? Answer: 7 hours

6. What time (including maternity leave) will it be in Murmansk (2nd time zone) when it is 12 noon in London? Answer: 15 hours

7. Determine the standard time (including maternity leave) of Krasnoyarsk (6th time zone), if it is 11 o’clock in London. Answer: 18 o’clock.

8. What time is it in Omsk (5th time zone), when it is 15:00 in Moscow? Answer: 18 hours

9. How much time, taking into account maternity leave, will it be in Vladivostok (9th time zone) when it is midnight in London? Answer: 10 hours

To solve problems on determining standard time, you need to: carefully study the map of time zones in Russia and the world. Pay attention to the time difference in Russia and the world, have a clear idea of ​​zone, maternity, and Moscow time; remember the location of the date line.

Main theses of the topic: time zones of the world.

In each time zone, time is calculated by the meridian passing through its middle. This time is called zone time. It differs from the time of the neighboring zone by exactly one hour. The belts are counted from west to east. The zone along whose axis the Greenwich meridian passes is taken to be zero.

Local time is the time on one meridian at each point.

The territory of Russia is located within 11 time zones, from Moscow 2 to 12. Eleven hours separate the Kaliningrad region from Chukotka in the east.

Date line. In order to avoid confusion with the days of the year, an international date line has been established. It was drawn according to geographical maps approximately along the 180th meridian, bypassing the land. If we cross this line from west to east, then we will complete T+1 revolution, i.e. T+1 day, and, oddly enough, we will arrive on yesterday. Consequently, crossing this line from west to east, we must count the same day twice. When crossing the date line from east to west, on the contrary, skip one day.

Maternity time. By a special resolution (decree) of the Council of People's Commissars in 1930, standard time in the country was moved forward one hour. This was done for more efficient, full use of daytime.

Summer time. The length of the day increases in summer. Daylight saving time is introduced throughout the country on the last Sunday in March: clocks are moved back one hour. In autumn, on the last Sunday in October, daylight saving time is cancelled.

Problems to determine standard time .

1. Determine summer time in Yakutsk, in Magadan, if it is 10 o’clock in the morning in Moscow?

2. Determine the time in Brazil if it is 8 o’clock in Moscow?

3. By what system would time be measured on Earth if it did not rotate around its axis?

4. The ship, which sailed from Vladivostok on Saturday May 24, arrived in San Francisco (USA) exactly 15 days later. On what date, month and day of the week did he arrive in San Francisco?

5. It’s noon on the prime meridian, and 17-00 on the ship. In what ocean is the ship sailing?

6. If it is 12-00 in London, what time is it in Moscow and Vladivostok?

7. What time is it in Magadan local time, if on the Greenwich meridian line

12-00?

8. A resident of Alaska flew to Chukotka. How many hours should he move the hands to?

9. How many times can you celebrate New Year in our country?

Solving problems for local and standard time.

Task №1.

At 30°E Wednesday, January 1, 18:00 local time. What day of the week, date and time is on the 180th meridian?

Solution:

1. Find the difference in degrees and time between 30° East. and 180 degree meridian:

180°- 30°E = 150°: 15°/hour = 10 hours (this is the time difference).

Since the 180th meridian is located east of 30°E, then by local time 30°E. (18 hours) you need to add the time difference i.e. 10 hours:

18 hours + 10 hours = 28 hours (1 day and 4 hours).

Answer:

Task No. 2.

In Kyiv, standard time is 12 o'clock. In point A the local time is 9 o’clock, and in point B it is 14 o’clock.

Determine the geographic longitude of points A and B.

Solution:

The longitude of Kyiv is 31° east.

For point "A"

1)12 hours – 9 hours = 3 hours;

2)3 hours×15° = 45°;

3)45° - 31° = 14°W

For point "B"

1)14 hours – 12 hours = 2 hours;

2)2 hours×15° = 30°;

3)31°+30° = 61°E.

Answer:

The longitude of point A is 14°W, the longitude of point B is 61°E.

Task No. 3.

At the 180 meridian - Monday, May 15, 15:00 local time. What day, day of week and local time at: 45°E, 150°E, 0°longitude, 15°W, 170°W.

Solution:

a)180° - 45° = 135: 15/hour = 9 hours

9 hours – time difference between 180° meridian and 45° east. Since 45° E. is located east of the 180° meridian, then

Answer:

b)180° – 150° east. = 30°, 30°: 15/hour = 2 hours,

15 hours – 2 hours = 13 hours.

Answer:

c)180° – 0° = 180°, 180°: 15/hour = 12 hours

15 o'clock - 12 o'clock = 3 o'clock in the morning.

Answer:

d)180° + 15°w. = 195°, 195°: 15/hour = 13

taking into account the direction of rotation of the Earth from west to east:

15 o'clock - 13 o'clock = 26 o'clock or 2 o'clock in the morning, May 15, Monday.

Answer:

e)180° – 170°W. = 10° × 4min = 40 minutes

15 hours + 40 minutes = 15 hours 40 minutes.

Answer:

Task No. 4.

The plane took off from Pretoria (ΙΙ time zone) at 15:00 on December 1st and flew northeast. After 9 hours, he crossed the 180th meridian, and after another 2 hours he landed in Honolulu (14 time zone). What time and what date will it be in Honolulu at the time of landing.

Solution:

1. Determine the time difference between cities

24 - 14 – 2 = 12 hours

2. Determine the time in Honolulu at the time of landing from Pretoria. Since Honolulu is located further west, then

15 – 12 = 3 hours

3. Standard time in Honolulu when the plane lands

3 + 9 + 2 = 14 hours.

Answer:

The height of the sun above the horizon.

Determination of geographical coordinates.

Task No. 1.

Determine the geographic latitude of the city if it is known that on the days of the equinox the sun at noon is above the horizon at an altitude of 63° (the shadow falls to the south).

Solution:

The point is located in the southern hemisphere. The height of the sun on the days of the equinoxes is determined by the formulah= 90° - φ. Determine the latitude of the point φ = 90° - 63° = 27°S.

Task No. 2.

At what geographic latitude is city A located if the sun at noon on December 22 (the shadow falls to the south) is at an altitude of 70° above the horizon.

Solution:

From the conditions of the problem it follows that point A is located in the southern hemisphere, since the shadow falls to the south. The height of the sun for the summer solstice (December 22 – summer in the southern hemisphere) is determined by the formulah= 90° - φ + 23° 30"

From this formula you can find φ the latitude of the place i.e. city ​​A

φ = 90° - 70° + 23°30" = 43°30"S.

Answer:

Geographic latitude of the city A = 43°30"S.

Task No. 3.

Determine the geographical coordinates of the city - the capital, located west of Kyiv at 27°30". The North Star in this place is visible at a distance of 54° from the zenith point.

Solution:

1. The longitude of Kyiv is 30 ° 30 "E. We can find the geographical longitude of the city

λ = 30°30" – 27°30" = 3° east.

2. In the northern hemisphere, the geographic latitude of any point is equal to the angle between the North Star and the horizon line. Finding the geographic latitude:

φ = 90° - 54° = 36°N.

Answer:

Geographic coordinates 36°N. and 3°E.

Task No. 4.

In the city - the capital of the island state, the sun is highest above the horizon during the day at 4 o'clock GMT. Throughout the year, the height of the sun varies from 52° to 90°. Name the city and state.

Solution:

1. Determine the time zone of the city:

12 hours – 4 hours = 8 time zone

2. Determine geographic longitude knowing that every 15° there is a time difference of 1 hour.

8 hours × 15° = 120° east.

3. the city is located between the tropics, since the sun can be at its zenith (90°)minThe angle of incidence of the sun's rays of 52° makes it possible to determine the geographic latitude during the winter solstice

φ = 90° - 52° – 23.5° = 14.5°

The city has geographical coordinates of 14.5°N. and 120°E.

Answer:

Manila, Philippines.

How to determine local time. As you already know from the 7th grade geography course, at the same moment in different points of the planet, lying on different meridians, there will be different local (Those. solar )time . You know that this is due to the rotation of the Earth around its axis. The time will be the same only at all points lying on the same meridian. So, on the western and eastern outskirts of even one settlement, local time will be different. This difference will increase with increasing distance between the meridians. So, on neighboring meridians, drawn through 15 °, the difference in local time is 1 hour, Drawn through 1 - 4 minutes, Drawed through 1 "(one minute, one degree is divided by 60 minutes) - 4 s (it is at such angular distances that the points rotate one meridian for specified periods of time).

In this case, the local time on the meridian located east of which point is ahead of the time in it, and on the more western meridian is behind. For example, if local time is Kyiv afternoon tea (12 noon), then at Donetsk It’s already 12:29 pm, And at Lvov at this moment - only 11 hours 33 minutes 56 seconds. Consequently, in order to establish the exact time at different points, knowing it at one of them, it is necessary to carry out such calculations.

a) Kyiv - 30 ° 34 "E;

b) Donetsk - 37 ° 49 "E;

c) Lviv - 24 ° 03 "E.

2. Set the difference in longitude between points (in degrees and minutes):

a) between Donetsk and Kiev - 37 ° 49 "- 30 ° 34" = 7 ° 15 "E;

b) between Kiev and Lvov - 30 ° 34 "- 24 ° 03" = 6 ° 31 "E.

3. Convert the difference in longitude (from degrees and minutes) to the difference in time (in hours, minutes and seconds):

a) 7°15" = 7 x 4 xv15 x 4 s = 29 xv;

b) 6 ° 31 "= 6 x 4 x 31 x 4 s = 26 x 4 s.

the found values ​​show the difference in local time on the meridians drawn through Kyiv, Lvov and Donetsk.

4. Until the time known to us in Kyiv (12 hours), add (in the case of Donetsk, which lies east of Kyiv) or subtract from it (in the case of Lvov, which is located west of Kyiv) the resulting value:

a) if it is 12 o’clock in Kyiv, then the local time in Donetsk will be

12 h + 29 hv = 12 h 29 hv;

b) if it is 12 o’clock in Kyiv, then the local time in Lviv will be

12 hours - 26 times 4 s = 11 hours 33 times 56 seconds.

Time zones and standard time. It is almost impossible to use local time, which is different at each location, in everyday life. For convenience, they are used all over the world standard time . For this, as you know, the globe was conventionally divided by meridians into 24 stripes (according to the number of hours in a day) - into Time Zones(15° longitude each). In all points of one belt, they agreed to consider the time the same. Standard time takes the local time of the meridian passing through the middle of this zone (middle meridian).

Time zones are numbered from 0 to 23 in an easterly direction: the middle meridian of the 0th zone is Greenwich(Prime) meridian, 1st zone - meridian 15 ° east. d., 12th zone - 180th meridian, 23rd zone - meridian 15 ° W. d.

The time of the 0th zone is called Western European , 1st - Central European , another - Eastern European . The zone number indicates the standard time at the moment when the Greenwich meridian is north. The time difference between two neighboring zones is 1 hour. Moving around the globe from west to east, we must move the clock hand one hour forward when crossing the boundaries of each subsequent zone, and moving westward - one hour back.

The location of Ukraine relative to time zones is convenient: 95% of its territory lies in the second zone, only Lugansk and parts Donetsk And Kharkov regions- In the 3rd zone, and a small part Transcarpathian region- in the first belt. However, in practice, for convenience, the boundaries of time zones on land are drawn not strictly along the meridians, but taking into account state borders. Therefore, the entire territory of Ukraine is assigned to the second time zone. Standard time in our country is the average time for the second zone meridian (30, which passes almost through Kyiv. Therefore, in Ukraine the belt is also called Kyiv .

Amazing Ukraine

According to the time zone of the second zone, in addition to Ukraine, Belarus, Latvia, Lithuania, Estonia, Finland, Moldova, Romania, and Turkey also live in Europe. All of Ukraine's western neighbors, the countries of Central and most countries of Western Europe use Central European Time, while Great Britain, Ireland, Iceland and Portugal use Western European Time. In the Russian territories adjacent to the borders of Ukraine, the so-called Moscow time is in effect, which is 1 hour ahead of Moscow

Ri c . Time zones of the world

Summer time. Every year in Ukraine it is introduced summer time : On the night of the last Sunday in March, the clock hand is moved forward one hour. This makes it possible to use the light part of the day more fully and save energy. On the night of the last Sunday in October, the clock hand is turned back an hour, restoring standard time.

The introduction and abolition of summer time is carried out synchronously by most European countries.