The benefits and necessity of sunlight forthe human body is not questioned. Any of us knows that without him existence is impossible. In winter, we all experience a more or less severe deficiency of it, which negatively affects our well-being and undermines the already unstable immunity.
With the onset of the cold season light day,the duration of which is rapidly decreasing, is increasingly giving way to rights. Nights are made longer and longer, and the days, on the contrary, are shorter. After the period of the winter equinox, the situation begins to change in the opposite direction, which most of us are looking forward to. A lot of people want to accurately navigate the length of daylight now and in the short term.
As is known, the number of hours of light per daybegins to increase at the end of the so-called winter solstice. At its peak, the daylight hours are fixed annually, the duration of which is the lowest. From a scientific point of view, the explanation consists in finding the sun at this particular time at the most distant point of the orbit of our planet. The elliptical (i.e. elongated) shape of the orbit has an effect on this.
In the northern hemisphere, the winter solsticeIt happens in December and falls on the 21-22 number. A slight shift of this date depends on the dynamics of the moon and shifts in leap years. At the same time, the southern hemisphere is experiencing a reverse summer solstice.
A few days before and after the date of eachSolstice fluorescent body does not change its position. Only two or three days after the darkest days are over, the light period begins to gradually increase. And at first, this process is practically not visible, since the addition occurs only for a few minutes a day. Later it begins to lighten faster, this is due to the increase in the speed of solar rotation.
Actually increasing the duration of the lightDay in the northern hemisphere of the Earth begins no earlier than December 24-25, and it occurs until the very date of the summer solstice. This day alternately falls on one of three: from 20 to 22 June. The increase in daylight has a significant positive effect on people's health.
According to astronomers, the winter solsticeIt is considered the moment when the sun reaches the lowest angular height above the horizon. After a few days, the sun can begin its rise even a little later (for a few minutes). The increase in the length of daylight hours is observed in the evenings and is due to the increasingly late sunset.
This effect is also due to an increase inthe speed of the earth. You can verify this by looking at the table, which reflects the sunrises and sunset. As astronomers say, the day is added in the evening, and unevenly on both sides. The graph of the duration of daylight provides a visual representation of the dynamics of this process.
Every day the sunset shifts for a few minutes.Accurate data can be easily traced through the relevant tables and calendars. As the scientists explain, this effect is caused by a combination of daily and annual sun movements across the sky, which in winter is a little faster than in summer. In turn, this is caused by the fact that, turning at a constant speed around its own axis, the Earth in winter is located closer to the Sun and moves in an orbit around it a little bit faster.
Elliptical orbit that movesour planet has a pronounced eccentricity. This term refers to the amount of elongation of an ellipse. The point of this eccentricity as close as possible to the Sun is called perihelion, and the most distant is called aphelion.
Kepler’s laws state that for movingorbital in the form of an ellipse of the body is characterized by a maximum speed in those points that are as close as possible to the center. That is why the movement of the sun in the sky in winter is a little faster than in summer.
According to astronomers, the Earth’s point of passage is around January 3, and the aphelion, July 3. It is possible to change these dates by 1-2 days, which is associated with the additional influence of the movement of the moon.
The ellipse-like shape of the Earth’s orbit hasimpact also on climate. During the winter in the Northern Hemisphere, our planet is located closer to the Sun, in the summer - further. This factor makes the difference between the climatic seasons of our northern hemisphere slightly less noticeable.
At the same time, in the southern hemisphere this difference is morenoticeable. As established by scientists, one revolution of the recess point occurs in about 200,000 years. That is, after about 100,000 years, the situation will change to the exact opposite. Well, we will live and see!
If you go back to the current problems, then more importantthe only thing for us is the fact that the emotional, mental and physical state of the inhabitants of the earth improves in direct proportion to the increase in the duration of the light time of day. Even a slight (for a few minutes) lengthening of the day immediately after the winter solstice has a serious moral effect on people tired of dark winter evenings.
From a medical point of view, a positive effectsunlight on the body due to increased production of the hormone serotonin, the head of the emotions of happiness and joy. Unfortunately, in the dark it is produced extremely badly. That is why the increase in the duration of the light gap by acting on the emotional sphere leads to a general improvement in health and strengthening of human immunity.
A significant role in the sensations of each of us playdaily internal biorhythms that are energetically tied to the alternation of day and night since the creation of the world. Scientists believe that our nervous system can only adequately work and cope with external overloads by regularly receiving a well-defined dose of sunlight.
If the sun's rays are not enough, the consequencescan be the saddest: from regular nervous breakdowns to serious mental disorders. With an acute lack of light, the most actual depressive state can develop. And seasonal disorders of affective character, which are expressed in depression, bad mood, general decrease in the emotional background, are observed very often.
In addition, modern citizens are still exposedone misfortune. Light day, the duration of which is too small for modern urban life, requires adjustment. We are talking about a huge, often excessive amount of artificial lighting, which receives almost any resident of the metropolis. Our body, unsuitable for such a quantity of artificial light, is capable of becoming entangled in time and falling into a state of desynchronosis. This not only leads to a weakening of the nervous system, but also to the exacerbation of any existing chronic diseases.
Consider now the concept of longitude of the day,actual for each of us in the first days after the winter solstice. This term denotes the time interval that lasts from sunrise to sunset, that is, the time during which our light is visible above the horizon.
This value is in direct proportion tosolar declination and geographical latitude of the point where it should be determined. In the equatorial region, the magnitude of the longitude 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.
Days when the duration of the night coincides withduration of the day, referred to as the days of the vernal equinox, or autumn. It takes place on March 21 and September 23, respectively. It is clear that the highest figure is the longitude of the day at the time of the summer solstice, and the lowest - on the day of the winter.
For the polar circles of each of the hemispheres, the magnitude of the longitude of the day exceeds 24 hours. We are talking about the well-known concept of the polar day. At the poles, it has a duration of as much as six months.
Longitude of the day anywhere in the hemisphere canto determine quite accurately using special tables containing the calculation of the length of daylight hours. Of course, this figure changes daily. Sometimes for a rough estimate uses such a thing as the average length of daylight by month. For clarity, we consider these figures for the geographical point where the capital of our country is located.
In January, a light day at the latitude of our capitalaverages 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.
During 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 the June days are the longest, which corresponds to the summer solstice.
In the autumn daylight continues to decline.In September and October, its duration is 12 hours 45 minutes and 10 hours 27 minutes, respectively. The last cold dark months of the year — November and December — are famous for their short, light days, with an average day length of less than 8 hours 22 minutes and 7 hours 16 minutes, respectively.
