Noon - this is how much time? Time of day - day. AM is the time

Time, as is known, is a relative concept, and in some cases also extensible. We used to share it for years, months, days, hours, minutes and seconds. But such term as noon is how much time? It turns out that the answer to this question is not so simple as it seems at first glance. And if you say that noon is twelve o'clock in the afternoon, then you can make a mistake. Does this mean that this term is as relational as all human time? Yes and no. Let's try to study this problem more deeply.

Day

To answer the question "Noon - this is how much time?", You need to know the yardstick of what it is. This astronomical constant serves as a definition for the middle of the day. And how do they differ from the date or the day? In English, which, as we know, is more functional than Russian, there is no such analogue in the dictionary. The average philistine says day, which means "day". For a strict description of the day as such, a more precise term is used - 24 hours. Also common is the phrase day and night. And in the Slavic languages, the words "day" or "add" come from the words "meeting" and "joint". Thus, a new day begins either with the burning of the sunset, or at dawn, that is, when the dark and light time of the day meet. Noon, as it appears from the etymology of the word, means the very middle of the day.

Solar and stellar days

We used to think that a given time unit consists of twenty-four hours, but astronomers distinguish between sunny and stellar days, which are not equal to each other. Our planet rotates around its axis for 24 hours, but because of the Earth's orbital motion the Sun moves, so the star day lasts twenty-three hours, fifty-six minutes and four seconds. There is something to think about! As the Earth moves around the Sun unevenly. To correct the error, a so-called "leap second" is introduced regularly on December 31 or June 30. To do this, determine the noon - this is how long - at the Greenwich Observatory at the date of the spring or autumn equinox. The upper edge of the solar disk should ascend above the ground at 6 am and disappear completely out of sight at 6 pm. And at noon the middle of the luminary is at the highest point in the sky - at the zenith.

Day and night

In everyday life, we often replace these two concepts. So, we say "June 18th day", meaning by this the whole time period, from 0 to 23 hours, 59 minutes and 59 seconds. But it was not always the middle of the day. The ancient Greeks, Egyptians and Slavs counted the beginning of a new day from dawn. In the Jewish tradition, the yemama, that is, the day, began when the first star was shining in the sky (that is, after sunset). The rudiment of such a calculation of time remained in the "eve" during the celebration of great religious holidays, so it was difficult to compare the two values. Noon - this is how much time? It could be like six hours, and all seventeen. Especially in light latitudes the light day depends on the seasons. And how then to determine the noon behind the polar circle, where our luminary may not be shown for days?

Constant and relative

It would seem that everything is extremely simple. The sun at noon stands at its zenith, that is, reaches its maximum height in the sky. The light in our latitudes rises not exactly in the east, but slightly to the south, and it moves along the midday edge of the sky. Thus, when it reaches its maximum height and begins its movement towards the sunset, its location can be defined as strictly southern. At the equator, noon is when the luminary shines evenly overhead. And in the southern hemisphere at this time the sun can be seen exactly in the north. Time of day - day, morning, evening and night - varies depending on the season. In the summer it gets dark late, white nights are seen somewhere, and in the winter the evening goes down early. But noon is a constant. At this time, the shadows become the shortest (in the tropics they generally hide under their feet), so noon to calculate easily. We go to the level platform, we break into the ground a vertical peg. Next install the compass. When the shadow from the peg is pointing exactly to the south, it means noon came.

What prevents you from determining the exact time

It's all theory. And what happens if we really decide on this simple experiment? Let's say we conduct our experience in Berdyansk (Ukraine). The result of the experiment shows that there noon comes at 11 o'clock and 40 minutes. And in Transcarpathia this indicator is shifted for half an hour in another direction - 12:30. Why is noon on the clock does not correspond to the true solar zenith? Here, in the laws of nature, policy considerations are invaded. To avoid confusion in the timetable of transport and other inconveniences, the states are trying to unite all their territories under one time zone, and only the giant powers, for example, Russia or the United States, are forced to divide the lands in time. Conventionally, the entire globe is divided into 24 time zones. Universal time is checked by Greenwich Mean Time. This is the zero time zone (UT0). All of Western Europe, except Britain, Ireland and Portugal, lives in the UT + 1 zone. At the same time, the true noon is calculated for the territory located on the borders of Poland and Germany. Thus, in Spain the sun reaches the zenith when the dial is already about one o'clock in the afternoon.

Winter and summer time

If we conduct our experiment with a peg and compass in the Russian Federation, then we will need a lot of patience. Why? And you forgot how a few years ago on the last Sunday in March, all the shifted hands for an hour ahead? The true time is winter time. And in the summer even in Moscow noon comes at one o'clock in the afternoon. For the first time the so-called "decretal" time in our territory was introduced in 1930 "to save electricity." Then in the years of Perestroika it was canceled. Then they entered again. And finally, Russian doctors came to a strange conclusion: since the transition twice a year to a new time has a negative effect on the human body, you need to leave it summer. Why not winter, left for brackets.

What is PM and AM?

Time simple layman used to measure in terms of before and after noon. Although we accept a 24-hour division of the day, most people look at the round dial, divided into twelve sectors. And often indicates the hour, which shows a short arrow. In this case, add the time of day. So it turns out "two o'clock in the morning", "three days", "six evenings". In the British Empire , it was customary to point out otherwise. Namely, focusing on the afternoon. They even said hello: "Good afternoon!" - it means "good afternoon". This time the calculus has survived and now, moreover, it has also been applied in the countries of the former British colonies. It is there that you can meet such strange expressions as 8 AM and 3 PM. In Russian it means eight in the morning and three in the afternoon. The tradition of sharing time before noon and after came from medieval Latin. The abbreviation itself testifies to this. So, AM is an abbreviation for ante meridiem (before noon). And PM, respectively, indicates a time interval between 12 o'clock in the afternoon and midnight.