Why is there a half hour difference in time difference?

Due to the rotation of the Earth, the east moment is earlier than the west.

The rotation of the earth is 1 day, and it takes 24 hours to rotate the meridian 360°, so 1 hour turns 15° longitude, that is, the difference of 1° longitude time is 4 minutes.

The time zone is not an hour by an hour", referring to the zone time difference, which is measured in whole hours.

I'm here Why is another place, it's the time difference of the local time. The time difference between local time can be accurate to the minute, minute, second, and second. According to your material, "here for me" is to the east of "another place", two and a half hours earlier, which is 150 minutes, indicating that "here for me" is a place of longitude to the east of "another place".

Therefore, the local time difference is not a full hour time difference.

The local time is determined at 12 noon at the time of the day when the sun is at its highest. The zone time is determined to be the time when the highest solar height of the day on the meridian of the time zone - ** meridian is determined to be 12 noon, and this 12 points is regarded as the 12 o'clock of the entire time zone. Therefore, the time difference can only be the time difference of the whole hour.

The Earth is divided by the morning and dusk lines, day and night, and the Earth is a 360° oblate sphere, and according to the speed of its rotation, the difference between the two places is 15°, and the time difference is one hour. So you can look at the difference as a difference of half an hour. If you're happy, you can even divide it even more

The time zone is an hour by an hour, yes, but when we usually talk about time differences, it's generally between countries.

For example, the time difference from China to the United States, the time difference from China to India. It is not to say that there is a two-hour time difference between East 8 and East 5.

So the question that you're asking is the time it takes for the country.

For example, China uses the time in the East 8 Zone, and Japan uses the time in the East 9 Zone, and the time difference is one hour.

India, on the other hand, is using time in the East Zone. So the time difference between China and India is 2 and a half hours.

The point is that some countries use standard time not in the whole time zone, but in the middle half of a time zone.

Do you understand?

There are half-time zones, and some countries are relatively small, or they are a little more detailed.

These are special times set by the state.

For example, there are Iran, India, Myanmar, Central Australia, etc.

There are countries with half-time zones, although very few.

In India, for example, the time in the Eastern Zone is used.

It is determined according to the difference in the time of sunlight exposure.

The Earth is a sphere so

The time zone is divided for the convenience of timekeeping and time conversion in countries around the world. A country can determine its own standard time according to its own needs, and it is not necessary to use the time of one time zone, nor may it all use the standard time of a certain time zone. For example, the United States has multiple time zones, and the time difference needs to be converted within the United States, while China, which also spans multiple time zones, only uses one standard time, and there is no need to convert the time difference in China.

It is normal for some countries to use half-time zones according to their own characteristics and requirements, such as India, Iran, Myanmar, some small island countries, etc., and there are many such countries. In these countries, although the time difference is half an hour instead of an integer multiple of one hour, it is more convenient for foreigners to check their watches when they come here.

To put it simply, a country can use a half-time zone if it wants to, and they have this right and freedom.

Because the rotation of the earth is simply understood because the earth is round, this causes the phenomenon of day and night alternation when the earth rotates, and the sunrise time of each point where the longitude is located is different. This makes the difference in time between different longitudes on the earth, referred to as time difference.

1. The difference between mean solar time and true solar time. The time difference is constantly changing throughout the year, with a maximum positive value of +14 minutes and 24 seconds and a maximum negative value of -16 minutes and 24 seconds, which is equal to zero 4 times.

2. The difference between the local time of two regions is called the time difference.

Local time: With the rotation of the earth, the sun rises in the east and sets in the west during the day, and the sun passes through the highest point in the sky of a certain place at 12 o'clock in the local time of this place, so there are different places on different meridians. The same time used in the same time zone is regional time, and the same time used in the whole world is universal time.

Longitude varies by one hour every 15 degrees in regional time and 4 minutes in local time every 1 degree.

The standard time for all locations is Greenwich Mean Time (plus ( + or minus ( - time difference for the number of hours and minutes marked in the time zone. Many countries also use daylight saving time (DST), such as the United States, which runs from April to September, an hour earlier.

The calculation method of time difference: the subtraction of the standard time (the number of real-time zones) of the two time zones is the time difference, and the time when the value of the time zone is larger is earlier. For example, China is the East 8th Zone (+8), and the East of the United States is the West 5th Zone (-5), the time difference between the two places is 13 hours, and Beijing is 13 hours earlier than New York; If it is a period when daylight saving time is implemented in the United States, the difference is 12 hours.

The time in each country is artificially set.

All parts of the world divide the day into 24 hours, and all of them regard the time when the sun is in the right time as noon, which is 12 o'clock. However, since the Earth is a sphere and is still rotating, there is a sequence of times when the sun reaches the right space. The western ones are later than the eastern ones because the earth turns from west to east.

In order to avoid confusion in the exchange of time between people around the world, various countries have reached synchronicity and divided the world into different time zones. The same noon time is generally used in the same time zone. The time zones are one hour apart.

When you talk about the time, you have to indicate which time zone it is. This avoids confusion. Of course, a region may not necessarily adopt the standard time to which the defeated area belongs.

Rather, it takes the time of the big city or the capital of the trembling of the country to which this region belongs. For example, although China has crossed 5 time zones, the whole country uses Beijing's East 8th District time. Of course, the time in different places can be converted according to the time zone.

The time difference is due to the fact that the earth is a sphere, and the sun shines at the same angle at different diameters, such as the time overhead (12 noon). In order to take into account the daily habits and not to be too complicated, the radius is divided into the same time zone in the range of 15 degrees, and the world is divided into 24 time zones, and the adjacent time zones are one hour apart. On long-haul flights, jet lag can occur.

For example, Beijing departs for Europe at 7 a.m., and after a 12-hour flight, the Beijing escort time should be 19 o'clock, but when you arrive at your destination, it is still 11 a.m. local time. Travelers will obviously feel jet lag, which will affect their normal life.

"Time difference" in astronomy:

True solar time. The time difference from mean solar time is called jet lag. The reasons for the time difference are:

The orbit of the earth around the sun is elliptical, so that the apparent motion speed of the true sun on the celestial sphere is uneven. At the same time, there is an inclination between the Earth's orbital plane and the Earth's equatorial plane. When disturbing the bench from the true solar time to seek the flat sun, or from the flat sun to the true sun, the time difference needs to be corrected. The definition of jet lag can be written:

True Solar Time - Mean Solar Time.

In the past, some people also defined the time difference as the flat sun minus the true solar time. The value of the time difference is not related to the observer's position on the Earth, but only to the date of observation).

For a job with a post-work, the free time difference is equal to the minimum value of the difference between the earliest start time of the post-work and the earliest completion time of the work, i.e.:

For the work without immediate work, that is, the work with the end node of the network plan as the completion node, the free time difference is equal to the difference between the planned duration and the earliest completion time of the work, that is:

The free time difference of work with the end node as the completion node should be equal to the difference between the planned duration and the earliest completion time of the work. In fact, the free time difference of the work of the end node is necessarily equal to the total time difference.

The free time difference for other work is the horizontal projection length of the waveform line in the arrow line of that work. However, when the work is followed only by the imaginary work, there must be no waveform line on the working arrow line, and the shortest horizontal projection length of the waveform line in the imaginary arrow line immediately after the work is the free time difference of the work.

The difference in time between two regions is called the time difference.

Because the earth is round and rotates.

Because the earth is spherical, the sunlight cannot reach all of it, and in some places it is in the middle of the night, and in some places it is still noon, so scientists divide it into several time zones.