When will the day be added in the year? Shortest and longest day of the year

Daylight is the time from sunrise to sunset. Depending on what point in its orbit the Earth is located, revolving around the Sun, the duration also changes. daylight hours. The longest day of daylight is June 21, on this day its duration is 16 hours. The shortest day, which lasts only 8 hours, falls on December 21 or 22, depending on whether the year is a leap year. In the fall, on September 21 and March 21, nature marks the days of the autumn and spring equinox, when the length of daylight is equal to the length of night - the time from sunset to sunrise.

The length of daylight determines the annual cycle, which governs all life on planet Earth. At the same time, as the length of daylight hours changes, one season changes another: spring is followed by summer, autumn, winter and again. This dependence can be seen especially clearly in the example of plants. In the spring, as the length of daylight increases, sap flow begins in them; in the summer you can observe their blossoming, withering, and in the winter - suspended animation, a sleep similar to death. But, perhaps not in such an obvious form, the length of daylight also affects a person.

The influence of daylight hours on humans

Man, as part of the planet's biosphere, is also sensitive to how long daylight hours last, despite the fact that his life regime is subject to the daily work rhythm. However, carried out medical research confirmed that in winter the metabolic rate in the human body decreases, resulting in increased drowsiness and the appearance of excess weight.

The lack of sufficient natural light also affects the psycho-emotional state. IN winter time, and also at the beginning of spring, many complain of depression, bad mood, headaches, insomnia and irritability. Dysfunction provokes disruptions in the functioning of other organs and systems. The synthesis of natural vitamin D in the body decreases, which entails a decrease in the protective properties of the immune system, therefore total quantity diseases and exacerbations of chronic pathological processes at this time of year are the highest. Doctors advise at the end of winter - beginning of spring to get out into nature at least on weekends, spend more time during the day on fresh air, this will help cope with bad mood and improve overall well-being.

Benefit and necessity sunlight for the human body is not in doubt. Any of us knows that without it it is impossible to exist. In winter, we all experience a more or less severe deficiency of it, which negatively affects our well-being and undermines our already unstable immunity.

What happens to daylight hours?

With the onset of the cold season, daylight hours, the duration of which is rapidly decreasing, are increasingly losing ground. The nights become longer and longer, and the days, on the contrary, become shorter. After the winter equinox the situation begins to change in reverse side, something most of us look forward to. Many people want to accurately navigate the length of daylight hours now and in the near future.

As you know, the number of daylight hours in a day begins to increase at the end of the so-called winter solstice. At its peak, daylight hours are recorded annually, the duration of which is the shortest. From a scientific point of view, the explanation is that the sun is at this very time at the most distant point in the orbit of our planet. This is influenced by the elliptical (that is, elongated) shape of the orbit.

In the northern hemisphere it happens in December and falls on the 21st-22nd. A slight shift in this date depends on the dynamics of the Moon and shifts in leap years. At the same time, the southern hemisphere is experiencing the reverse summer solstice.

Daylight hours: duration, timing

A few days before and after the date of each solstice, the daylight does not change its position. Only two or three days after the end of the darkest day does the light period begin to gradually increase. Moreover, at first this process is practically invisible, since the increase occurs only for a few minutes a day. In the future, it begins to brighten faster, this is explained by an increase in the speed of solar rotation.

In fact, the increase in the length of daylight hours in the northern hemisphere of the Earth begins no earlier than December 24-25, and it occurs until the date of the summer solstice. This day alternately falls on one of three: from June 20 to June 22. Increasing daylight hours has a noticeable positive effect on people's health.

According to astronomers, the winter solstice is considered the moment the sun reaches its lowest angular height above the horizon. After it, within a few minutes the sunrise may begin even a little later (by a few minutes). An increase in the length of daylight hours is observed in the evenings and occurs due to an increasingly later sunset.

Why does this happen

This effect is also explained by the increase in the speed of the Earth's movement. You can verify this by looking at the table showing sunrises and sunsets. As astronomers say, the day increases in the evening, but unevenly on both sides. The graph of daylight hours gives a clear idea of ​​the dynamics of this process.

Every day the sunset shifts by a few minutes. Accurate data can be easily tracked using the appropriate tables and calendars. As scientists explain, this effect is caused by a combination of the daily and annual movements of the sun across the sky, which is slightly faster in winter than in summer. In turn, this is due to the fact that, rotating at a constant speed around its own axis, the Earth in winter is located closer to the Sun and moves in orbit around it a little faster.

The elliptical orbit along which our planet moves has a pronounced eccentricity. This term denotes the amount of elongation of an ellipse. The point of this eccentricity that is closest to the Sun is called perihelion, and the most distant point is called aphelion.

It is argued that a body moving in an elliptical orbit is characterized by maximum speed at those points that are as close as possible to the center. That is why the movement of the sun across the sky in winter is slightly faster than in summer.

How does the Earth's orbit affect climate?

According to astronomers, the Earth passes the perhelion point on approximately January 3, and aphelion on July 3. It is possible that these dates may change by 1-2 days, due to the additional influence of the Moon's movement.

The elliptical shape of the Earth's orbit also affects climate. During winter in the Northern Hemisphere, our planet is located closer to the Sun, while in summer it is further away. This factor makes the difference between climatic seasons our northern hemisphere.

At the same time in Southern Hemisphere this difference is more noticeable. As scientists have established, one revolution of the perhelion point occurs in approximately 200,000 years. That is, in about 100,000 years the situation will change to the exact opposite. Well, we'll wait and see!

Give me sunshine!

If we return to current problems, the most important thing for us is the fact that the emotional, mental and physical condition of the inhabitants of the Earth improves in direct proportion to the increase in the duration of daylight hours. Even a slight (several minutes) lengthening of the day immediately after the winter solstice has a serious moral effect on those tired of the dark winter evenings people.

Medically, positive influence sunlight on the body is explained by an increase in the production of the hormone serotonin, which controls the emotions of happiness and joy. Unfortunately, it is produced extremely poorly in the dark. That is why increasing the duration of the light interval by influencing the emotional sphere leads to a general improvement in well-being and strengthening of human immunity.

A significant role in the sensations of each of us is played by daily internal biorhythms, which are energetically tied to the alternation of day and night that has continued since the creation of the world. Scientists are confident that our nervous system can work adequately and cope with external overloads only by regularly receiving a very specific dose of sunlight.

When the light is not enough

If sun rays is not enough, the consequences can be the most tragic: from regular nervous breakdowns to serious mental disorders. With an acute lack of light, a real depressive state can develop. And seasonal affective disorders, which are expressed in depression, bad mood, a general decrease in the emotional background is observed quite often.

In addition, modern city dwellers are subject to another misfortune. Daylight hours, which are too short for modern city life, require adjustment. It's about about the huge, often excessive amount of artificial lighting that almost every resident of the metropolis receives. Our body, unadapted to such amounts of artificial light, is capable of getting confused in time and falling into a state of desynchronosis. This leads not only to weakening nervous system, but also to the exacerbation of any existing chronic diseases.

What is the length of the day

Let us now consider the concept of day length, which is relevant for each of us in the first days after the winter solstice. This term refers to the period of time that lasts from sunrise to sunset, that is, the time during which our star is visible above the horizon.

This value is directly dependent on solar declination and geographical latitude points where it needs to be determined. Near the equator, the length of the day does not change and is exactly 12 hours. This figure is borderline. For the northern hemisphere, in spring and summer the day lasts longer than 12 hours, in winter and autumn - less.

Autumn and spring equinox

Days when the length of the night coincides with the length of the day are called the days of the vernal or autumn equinox. This also happens on September 23rd, respectively. It is clear that the length of the day reaches its highest figure at the moment of the summer solstice, and the lowest - on the day of the winter.

Beyond the polar circles of each hemisphere, the length of the day goes off scale in 24 hours. We are talking about the well-known concept of polar day. At the poles it lasts as much as six months.

The length of the day at any point in the hemisphere can be determined quite accurately using special tables containing calculations of the length of daylight hours. Of course, this figure changes daily. Sometimes for a rough estimate he uses such a concept as average duration daylight hours by month. For clarity, let's consider these numbers for that geographical point, where the capital of our country is located.

Daylight hours in Moscow

In January, daylight hours at the latitude of our capital average 7 hours 51 minutes. In February - 9 hours 38 minutes. In March its duration reaches 11 hours 51 minutes, in April - 14 hours 11 minutes, in May - 16 hours 14 minutes.

Over the three summer months: June, July and August, these figures are 17 hours 19 minutes, 16 hours 47 minutes and 14 hours 59 minutes. We see that it is June, which corresponds to the summer solstice.

In autumn, daylight hours continue to decrease. In September and October, its duration is 12 hours 45 minutes and 10 hours 27 minutes, respectively. Record short on bright days The last cold, dark months of the year are famous - November and December, the average day length of which does not exceed 8 hours 22 minutes and 7 hours 16 minutes, respectively.

Sunlight is very important for the development and growth of every living organism on planet Earth. Everyone feels its shortage, especially during periods of decreasing daylight hours and increasing nights. These changes are cyclical in nature. Every year, the equinoxes are celebrated in spring and autumn, when the lengths of day and night are compared. In winter and summer, the duration of day and night time is not the same. In winter, the shortest day and the longest night are celebrated, and in summer, on the contrary, the longest day and the shortest night. Such days are called solstice days.

When does the length of daylight increase in 2019?

Decreasing and increasing the length of daylight hours has become commonplace for people. However, when the day gets better, it brings much more joy. Everyone is waiting with great anticipation for the day to begin to increase. After all, for most people this is a kind of turn and approach to spring, even though the whole winter is still ahead.

The shortest day in 2019 falls on December 21st. On this day, the Sun crosses the longest point of the Earth's orbit, which causes the minimum duration of daylight hours. After this, daylight hours begin to gradually increase until June 22, and then decrease again in a cycle.

This date marks the longest day of the year and the shortest night. After the December solstice, sunlight begins to gain ground, increasing each day by a few minutes. On March 22, day and night will be equal in length. This will be the spring equinox. On this day, the earth's axis is tilted to the maximum towards the Sun, which is why a person can see it very low above the horizon. The intensity of the increase in daylight directly depends on the inclination of the Sun and the speed of its revolution.

It is worth noting that the increase in daylight hours after the winter solstice is not due to the fact that the sun rises earlier, but because it sets later. Thus, it turns out that the day begins to increase in the evening.

Why is this happening? This is all due to the elongated orbit in which the Earth rotates around the Sun, thus being a little closer to it. There may be a difference of more than one day between the moment when the Earth is as close as possible to the Sun and the day of the winter solstice.

What does increasing and decreasing the day mean for a person?

The human body is very sensitive to changes in daylight hours. It has been noted that in the months when the day is shortest, children born later suffer from schizophrenia. Previously, scientists associated this with a deficiency of vitamin D in the body of a pregnant woman, but recently scientists have put forward a version according to which the problem may lie in melatonin (the key hormone responsible for human biorhythms) and the mother’s body temperature.

Accumulation of melatonin in the body expectant mother becomes highest during the winter solstice. Her body temperature drops significantly on the night of December 21-22, and this negatively affects the formation of the future baby’s brain: the hippocampus becomes smaller, and dopamine is not transmitted properly. According to scientists, such consequences can be easily avoided. To do this, a pregnant woman just needs to compensate for the lack of sunlight with artificial sources.

Changing the length of daylight hours also has a detrimental effect on the already formed brain of an adult. Research at the University of Liege has shown that the brain is most active during the summer solstice and least active during the winter.

What does the December solstice mean for different peoples of the world?

Since ancient times, the winter solstice, which falls on December 21, has been a very important day. There are many traditions associated with it. Once upon a time, people called the first month of the year Kolyaden. At this time, the birthday of Kolyada, the sun god, was celebrated. Rich tables were set for the holiday, and various ceremonies and rituals were performed. The festivities turned out to be quite large-scale. People thus revered the deity and saw off the fierce winter.

One of the traditions that has come down to us is caroling. Guys and girls put on the most beautiful outfits and walked around all the houses, singing holiday songs and wishing people goodness and prosperity. For this, the owners of the houses treated them various goodies. A special place occupied on the table wheat porridge, which was seasoned with nuts, dried fruits and honey. She was called a kolev. Wheels were burned on the streets, symbolizing the bright round Sun. Around the fires they danced and sang songs. In this way, people tried to help the much-desired Sun be reborn.

Traditions different nations have a lot in common, although they are carried out independently of each other. The main purpose of ritual actions is to try to gain support good forces for the coming year. Special significance had the winter solstice for primitive people. This is due to the fact that they could not be sure of the future. People did not know how well they had prepared for winter and whether they had enough supplies to survive this period. During the first four months of the new year they often went hungry.

The celebration of the “half” of winter was the final celebration before the start of the difficult winter period. Almost all the livestock was sent to slaughter, since it was almost impossible to feed them in winter. That's why greatest number meat products consumed during the solstice, which falls in winter.

Christians celebrate the Nativity of Christ on the winter solstice. U Orthodox people this holiday is celebrated two weeks later. On this day the Slavs honor Kolyada, and the Germans honor Yule. The Scandinavian peoples have a carnival dedicated to fire on the December solstice. The Chinese celebrate Dongzhi, thereby welcoming the imminent increase in the length of daylight hours and the addition of “positive energy”.

During the winter solstice, one of the traditions is taking warm aromatic baths. The Japanese believe that the aroma of citrus fruits improves health and prevents colds from entering the body. That is why on this day in many baths and hot springs people leave citrus fruit. Ancient traditions a lot has reached us.

As we see, sunlight plays a special role in the life of not only people, but also all living things on the planet. Everyone is looking forward to the first rays of sunlight to warm up after a long cold night. Ideal option for most it would probably be if the night were short and the day very long. But everyone has their own preferences. Therefore, we are content with what nature has given us.

Reduction in autumn-winter period the duration of daylight hours affects the deterioration of well-being and weakening of a person’s immunity, the change from the rising phase to the falling phase in all life cycles, an increase in the expenditure side of countries' budgets, the suspension of seasonal work in a number of sectors of the economy ( agriculture, construction and others).

The winter solstice marks the minimum daylight hours. On this day, the Sun crosses the farthest point of the ellipse along which the Earth rotates. This day for residents of the northern hemisphere of our planet occurs on December 21-22, while at the same time, for residents of the southern hemisphere, the summer solstice day of maximum duration begins.

Sunlight promotes the production of the hormone serotonin in the human body, evoking emotions joy and happiness. With short daylight hours, the production of serotonin is reduced, which depresses the emotional sphere of the body and leads to a deterioration in its condition. The equality of the length of day and night on the days of the autumn and spring equinoxes creates ideal conditions for daily biorhythms. Period of the cycle starting on the day autumn equinox, and ending on the day of the winter solstice, represents the stage of reduction of daylight hours in the phase of its lag from the duration of the night. This stage is the most unfavorable; during it, all life on Earth is increasingly oppressed. The second stage, beginning on the day of the winter solstice and ending on the day of the spring equinox, is also in the phase of the lag between daylight and night, but this lag is gradually decreasing, negative influence lack of sunlight gradually weakens. The less sunlight a person receives per day, the more susceptible he is to nervous breakdowns, up to depressive states and mental disorders. Technical civilization is trying to compensate for the lack of sunlight with artificial lighting, to which the human body is not adapted; it perceives artificially illuminated night hours as daylight hours, falling into the so-called state of desynchronosis, which aggravates chronic diseases.

At the same time, the population of the northern hemisphere is less affected by the changing seasons than the population of the southern hemisphere, because in winter Northern Hemisphere is closer to the Sun. The period from sunrise to sunset is called the length of the day. This value depends on geographic latitude. At the equator, the length of the day is a constant of 12 hours. In the northern hemisphere, in the autumn-winter period the length of the day is less than 12 hours, and in the spring-summer period it is more than 12 hours. At the Earth's poles, polar day and night last six months. Given the importance of day length, daily and monthly average day length tables have been compiled for each latitude.

For example, the minimum average monthly day length at the latitude of Moscow is 7 hours 16 minutes in December and 7 hours 51 minutes in January.

Changes in the length of daylight hours in different seasons are explained by the rotation of the Earth around its axis. If the Earth did not rotate, the day and night cycles would be completely different. Although, it is likely that they would be completely absent. Whether daylight hours shorten or increase depends on the time of year and where you are on Earth. In addition, daytime is affected by the angle of the Earth's axis and its path around the Sun.

Rotation duration

A 24-hour day is the time it takes for the Earth to complete a full revolution on its own axis, which is why the Sun appears in the same place in the sky the next day. However, do not forget that the Earth continues to move around the Sun, and this phenomenon has a huge impact on the length of daylight hours.

The actual time of one rotation of the Earth is somewhat shorter than we used to think: about 23 hours and 56 minutes. Astronomers discovered this by recording the time a star appeared in the same place in the sky the next day - a phenomenon called a star day.

Longer and shorter days

Although a solar day is 24 hours long, not every day contains 12 hours of daylight and 12 hours of darkness. In winter the nights are longer than in summer. This phenomenon is explained by the fact that the imaginary axis of the Earth is not located at a right angle: it tilts at an angle of 23.5 degrees. Actually, since our planet revolves around the Sun throughout the year, the northern half of the Earth tilts towards the Sun in the summer, causing long daylight hours and short night. In winter, this changes: our planet moves away from the Sun, and night time becomes longer. In spring and autumn, the Earth is neither tilted towards the Sun nor away from it, but somewhere in between, so day and night are the same at these times of the year. Here's how you can explain why the length of daylight hours increases in spring: our planet turns towards the sun!

Our number of daylight hours depends on our latitude and the fact of what the Earth's position is in relation to the Sun. The axis of rotation of our planet is inclined from the orbital plane and is always located in one direction - towards the polar star. As a result, the position of the earth's axis in relation to the sun constantly changes throughout the year.

Actually, it is this factor that influences the propagation of sunlight across the Earth’s surface at any given latitude.

Changing the angle changes the amount of solar energy that reaches certain areas of the planet. This causes a seasonal change in the intensity of sunlight reaching the surface and affects the length of daylight hours.

The change in intensity occurs because the angle at which rays from the Sun travel and hit Earth changes as the seasons change.

Let's prove it in practice

If you shine a flashlight on the ceiling, the area illuminated will change depending on whether you shine the light at a right angle or not. Similarly, the energy of the Sun spreads across different geographical areas when it reaches the surface of the Earth. It is more concentrated in our summer months when the sun is higher in the sky.

Between the summer and winter solstice, the number of daylight hours decreases, and the rate of decrease is greater the higher the latitude. The fewer hours of sunshine, the colder the nights. This is why the length of daylight in the spring increases: the planet gradually turns towards the Sun, absorbing more and more solar energy on one of its sides.

Since, parallel to its rotation around the Sun, the Earth also continues to rotate around its own axis, it makes one full revolution in 24 hours. Interestingly, the length of the day changes over time. So, about 650 million years ago, the day lasted about 22 hours instead of the usual 24!

Solstice

Solstice is a phenomenon when, at a certain position, the Earth's orbit marks its longest and shortest days year. Winter Solstice, occurring in the Northern Hemisphere, marks the shortest day, after which daylight hours begin to slowly increase. Summer solstice in the same hemisphere the longest daylight hours occur, after which it begins to become shorter. The solstice is also named after the month in which it occurs.

It is also important to understand that the length of daylight on the solstice depends on the hemisphere in which you are located. Thus, in the Northern Hemisphere, the June solstice marks the longest daylight hours of the year. While in the Southern Hemisphere, the June solstice marks the longest night.