A city where the sun can be seen at night. From which side of the world does the sun rise and where does the sun set below the horizon? Why white nights happen
The sun is the source of life for our planet. The heavenly luminary caresses us with its warmth, illuminates us during the day and gives joy to everything that exists on Earth. Another important function: orientation assistance. Thanks to the sun, we can determine the cardinal points and choose the right direction.
Sun way
Every morning, the gentle sun calls us to awakening and new discoveries in this world. wonderful world. And in the evening, it, making its slow move across the sky, goes beyond the horizon, making it possible to rest after a busy day. labor day. Where does this journey start? Where does the sun set at the end of the journey?
The ascent of the main luminary begins in the east. The sun leaves us at the end of the day in the west. After that, it continues its journey, but on the other side of our amazing planet. And in the morning it rises again in the east. This is how the described picture appears to us from the Earth. Interestingly, ancient people considered this view to be wrong. In that case, where does the sun actually set, and how does it reappear in the sky?
If you do not delve into the details of the worldview of the inhabitants of antiquity, then we can say that they are right. The fact is that our planet is part of the solar system, where the Sun is motionless and is in the center. The earth moves around it in its orbit and, in addition to such a movement, makes revolutions around its imaginary axis. The planet makes a complete revolution in 24 hours, in other words, in a day. That is why it seems to us that the places where the sun sets and where it returns again in the morning are unchanged.
View from space
If I had the opportunity to look at solar system far from space, (so that you can see absolutely all the planets), then the picture would be as follows: all celestial bodies of this system rotate in the same direction from west to east (counterclockwise). In fact - Venus rotates around its axis in the opposite direction to the rotation of other planets. There are astronomers' assumptions that a very powerful asteroid hit it many years ago and violated the direction of rotation with its impact. Uranus, too, under the influence of such forces, seemed to be overturned. Now, watching him, you see a picture of rotation as if from the side.
North Pole and other parts of the world
If a person could study the movement of the main luminary from the direction of the North Pole, then he would see the rotation of the Earth counterclockwise, as well as the place where the sun sets and how it rises. Visually, the movement of a celestial body will appear as a move from east to west. In fact, it will move east, and the Earth will rotate around its axis.
Interestingly, in different parts of the world the sun does not rise at the same time. For example, on the East Coast of the United States, this happens even 3 hours before those areas that are on the West Coast. Accordingly, the sunset in different parts of the world falls at different times.
dust
The immediate period of time before sunrise and before sunset is twilight. This is a particularly beautiful sight. The disk of a celestial body is located very close to the horizon, part of the rays enter the upper atmospheric layers and are reflected on the surface of the Earth. The duration of such a colorful spectacle lasts about 2 hours. But this is only in temperate latitudes. In the polar regions, before the sunset occurs, twilight lasts several hours. Directly at the poles, this period takes from 2 to 3 weeks! At the same time, at the equator before sunrise, twilight lasts only 20-25 minutes.
At this time, thanks to the optical effect, we see a stunning picture when the sun's rays illuminate the surface of the Earth and the sky with multi-colored tones.
Orientation: how to determine the cardinal points without a compass on the ground?
If there is a wristwatch with arrows (not electronic), then in the “horizontal” position they need to be turned by the hour hand in the sun. Having drawn an imaginary bisector between the number 12 and the direction to the heavenly body, we get the north-south line. It is also interesting that before noon, the south is to the right of the sun.
Understanding how to determine the cardinal points without a compass, a person will be able to navigate anywhere and go out in the right direction. This knowledge is very important, especially for tourists, forestry workers, hunters, sailors and people engaged in other activities.
The method described above can give relatively correct results in northern latitudes. In temperate it works only partly (especially in winter). IN southern regions the summer sun is high, so errors can occur. In addition, it is necessary to take into account the transitions to summer time and vice versa (since this affects the definition of noon).
It is also important to remember where the sun rises and where it sets in the middle latitudes. In these places, the main luminary rises in the summer in the northeast, and sets in the northwest. 3moi - in the southeast and southwest, respectively. Only 2 times a year, the sunrise occurs absolutely exactly in the east, and the sunset - in the west. These are the days of the equinoxes - March 21 and September 23.
Shadow and terrain orientation
There is another way to focus on the shadow. In unfamiliar places, when this need arises, you need to take into account different heavenly bodies. At night it can be a polar star, and during the day it can be the sun.
Understanding from which side the sun sets, you can determine other cardinal points and choose the right direction of the path. For example, in the northern latitudes, when the time of summer nights comes, the setting sun is close to the horizon. Therefore, the sky on the north side is lighter than on the south.
It is known that the highest solar position can be determined by the shortest shadow. This corresponds to noon. The direction of such a shadow points to the north. It is the same with the moon: if it is full and occupies the highest position above the horizon, then it is in the south. This is the time when there is enough light to distinguish shadows well. Similarly, with a full moon - the shortest shadow. It's midnight. The direction of the shadow will point north.
And, not letting the darkness of the night
To golden skies
One dawn to replace another
Hurry, giving the night half an hour.
A.S. Pushkin "The Bronze Horseman"
Many people try to get to St. Petersburg at the end of July to see the famous white nights, about which they talk and write a lot. White nights are a symbol of St. Petersburg, but it's amazing a natural phenomenon can be observed in Kazan, and in Arkhangelsk, and in Kirov, and in Samara, and in Pskov, and in Syktyvkar.
Why are nights as bright as days in some parts of the Earth?
We know that day turns into night due to the movement of our Earth. Night comes when the Sun in relation to a certain territory earth's surface to be below the horizon line and the light becomes insufficient. Therefore, it is dark at night.
The duration of the night period depends on the latitude of the location of the point on the earth's surface, the inclination of the planet's axis of rotation relative to the plane of its orbit, and the angle formed by the axis of rotation and the direction to the central luminary is also important.
White nights are nights in which natural light is reduced only to dusk. The sun does not set below the horizon at all, and around the clock we see a bright sky. Such white nights are called "polar days".
The Earth's axis is tilted, so the Sun illuminates our planet in different ways: in winter, the sun's rays do not reach the North, and in summer a huge amount of heat and light is shed on us. In science, white nights are "civil twilight" - the period from the sunset of the upper edge of the solar disk beyond the horizon until the moment when the Sun's immersion under the horizon does not exceed a few degrees. It happens that at night the Sun sinks quite a bit below the horizon (does not have time to completely sink), the night smoothly turns into day without the onset of darkness. On the days of the summer solstice, the sun does not fall below the horizon at all, and at latitudes above 65º, the entire northern polar region is illuminated - the polar day. And when the sun does not go down for a long time beyond the Arctic Circle, rays of scattered sunlight reach the subpolar regions.
From the equator to the latitude of 49º there are no white nights, and above 49º there is a "zone of white nights". In the Volgograd and Rostov regions (they are located at a latitude of 49º) there is one white night a year (June 22). And higher, to the north, the white nights become lighter and longer.
Muscovites can also watch the white nights, but here they are not as bright as in other cities. For almost three months from May 12 to August 1, the sun does not set in Yakutia. White nights can be seen in the following cities: Murmansk, Norilsk, Vorkuta, Cherepovets, Vologda, Berezniki, Magadan, Megion, Khanty-Mansiysk, Kotlas, Nizhnevartovsk, Nefteyugansk, Surgut, Syktyvkar, Petrozavodsk, Yakutsk, Ukhta, Noyabrsk, Nadym, Arkhangelsk, Severodvinsk.
Throughout Iceland, Finland, Greenland and Antarctica at certain times you can admire the white nights, as well as in some areas of Sweden, Canada, Norway, Estonia, Great Britain and Alaska.
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From a scientific point of view, the sun shines on us continuously during the day. Even beyond the clouds. But we are waiting for a truly bright sunlight, which brings back to life and brings cheerfulness.
But the inhabitants of some cities of the world already used to waiting for the sun, and rejoice at his unexpected appearance as a holiday. What to do if the cities are located in places where nature has not provided for many sunny days. But here it has its own special charm, and not to say that it is always gloomy.
Yes, London is a very "associative" city when it comes to cloudy weather, but in the approximate rating of "gloomy" cities, it is the brightest. Not to say that it rains more often in the capital of Great Britain than in Europe as a whole, but the clouds do not ignore this city. But if nature has given several sunny days one after another, this is a chance for tourists to see vibrant London.
Juneau, USA
Sees the sun approximately 67 days a year
How can the sunny capital of Alaska itself be? Therefore, the inhabitants of the largest capital among the states of America resigned themselves to fate. Paradoxically, the city is considered large, but the city itself is very small. More than 90% of the entire area is occupied by wild nature - mountains and forests in their original form. Add here the lack of bright sunlight and understand why there are so few people here.
Cologne, Germany
Sees the sun approximately 65 days a year
Cologne is a very status city for Germany. This is a large and ancient cultural center. Gothic architecture, famous museums, a unique cathedral, exhibitions, conferences, carnivals - this is a very active and noisy city. He has few shortcomings. As well as the sun.
Birmingham, UK
Sees the sun approximately 62 days a year
"White Bird" - this is how the name of the city is translated - a little magical place. It has always been associated with legends about alchemists, because local residents have been engaged in the mining industry for centuries, and it is there, somewhere in the depths of the earth, that the philosopher's stone is waiting. The "secret of darkness" of Kiruna is that it is very close to the Arctic Circle. Therefore, the sun is on schedule here - from May to July, and then twilight is getting closer until it turns into a polar night.
Reykjavik, Iceland
Sees the sun about 55 days a year
The harsh island of Bering is where this gloomy village is located. sunlight here is amazing and a rare thing, but otherwise the life of the 700 inhabitants who live there is not too different from the life of people in other Russian outbacks. In addition, the village even has its own airport for communication with major cities of Kamchatka. Nikolskoye is the only place in Russia where the rare Aleut people live compactly. These are natives of the Aleutian Islands of Alaska, and it is not surprising that the cloudy climate does not particularly bother them.
Passes along the latitude 49 °. There, the white night can be observed only once a year - on June 22. Further north, the duration of this period increases, and the nights themselves become more and more bright.
This phenomenon is also known as civil twilight. In fact, the evening is the time when the sun is already below the horizon, but signs of sunset are still visible. The earth is illuminated by diffused light, i.e. the rays of the already hidden luminary are received by the upper layers of the atmosphere and are partially scattered, and partially reflected and illuminate the earth. Objects are clearly visible without artificial lighting, clearly distinguishable, but this is no longer daylight - in clear weather, the first ones are visible in the sky.
Depending on the illumination or, strictly speaking, on the position of the sun relative to the horizon, experts distinguish between civil, navigational and astronomical twilight.
Civil twilight lasts from the moment of apparent sunset until the time when the angle between the horizon line and the center of the solar disk is 6 °, from 6 ° to 12 ° - navigational, from 12 ° to 18 ° - astronomical twilight.
Thus, white night is a phenomenon when evening twilight smoothly turns into morning twilight, bypassing the night, i.e. the period of minimum illumination of the earth's surface.
A bit of astronomy
If we consider the phenomenon from an astronomical point of view, we should remember that the earth's axis is located at an angle to the plane of the ecliptic, i.e. to the plane of the planet's orbit around the Sun, and this inclination does not change.
In fact, the angle of the earth's axis is changing. She describes a circle in space and at different times "looks" at different places in the starry sky. However, the period of this movement, in human understanding, is very long - almost 26 thousand years.
Thus, in the process of the Earth's movement in its orbit, the Sun illuminates either the northern or Southern Hemisphere. Moreover, the inclination of the earth's axis is such that at some points of the orbit, the sun's rays fall on one of the poles almost perpendicularly. On the illuminated hemisphere - summer. In the polar regions, at this time, there is a polar day, when the sun does not hide behind the horizon for many days in a row.
The other hemisphere is going through winter because the light is dim. The sun's rays, as it were, glide over the surface of the Earth and heat it poorly. The pole is in the shade, there is a polar night. In the polar regions of the illuminated hemisphere, although the Sun sets, it does not last long and is close to the horizon. So close that it can illuminate the surface of the planet with its rays scattered in the atmosphere. The white nights are coming.
Every day we observe various atmospheric phenomena. Most often, we do not think about their features and nature. But it is worth taking a closer look around - and we will notice that many of these phenomena are much more interesting than they seem at first glance. One of clear examples are twilight.
What is twilight? This definition refers to two time periods:
- the time interval between apparent sunset and nightfall;
- the period between night and apparent sunrise.
So, we answered the question of what is twilight. But it turns out that they are divided into three types:
- civil;
- navigation;
- astronomical.
In this article, we will talk in detail about the features of each of the varieties of twilight.
Civil twilight
In the image above, you can learn about "blue hour" and "golden hour".
Civil twilight begins at the moment when the Sun sets and ends after its center drops 6 degrees below the horizon. This kind of twilight is the lightest. For this reason, small stars cannot be distinguished in the sky. But under favorable atmospheric conditions, the brightest celestial bodies can be observed. So, in cloudless weather during the period of civil twilight, one can see Venus in the sky without the use of optical instruments.
During this period of time, you can see all ground objects almost as well as in the daytime. Therefore, in the morning civil twilight, you can start, and in the evening - complete work carried out in the open air. By the way, that's why they are called civilians - at this time you can see well without additional lighting.
At some latitudes, civil twilight can continue throughout the night. In other words, evening twilight instead of night gradually turns into morning. This phenomenon is called white nights. On the territory of Russia, they can be observed in St. Petersburg, Perm, Yakutsk, Vorkuta and a number of other cities.
Navigational twilight
After the end of the evening civil twilight comes the time of nautical twilight. You can also observe them before the onset of morning civil twilight.
During this period, the center of the Sun is located 6-12 degrees below the horizon. During navigational twilight, one can distinguish the vague outlines of terrestrial objects. However, without artificial lighting, it is not possible to see their details. It is impossible to distinguish the colors of objects during this period. For these reasons, field work without the use of lighting devices in such conditions is not carried out.
But during this period of time you can see all the navigational stars. At the same time, the horizon line is visible. This allows navigators to navigate in space using a sextant, measuring the angles between the horizon and the stars - therefore, twilight is "nautical".
It is not uncommon for military forces to launch attacks during navigational twilight. This is due to the fact that during this period it is most difficult for the enemy to detect them.
Astronomical twilight
Astronomical twilight is the period of time when the center of the Sun is 12-18 degrees below the horizon. With their onset, astronomers can begin to observe most celestial objects. During this period, not only large planets and stars are clearly visible, but also small bodies. However, objects with a particularly weak and scattered glow can only be seen at astronomical night.
However, the difference between night and astronomical twilight is clear only to those who specialize in the study of celestial bodies. For an ordinary observer, the transition of astronomical twilight into night is completely imperceptible. In other words, they are perceived as part of the night.
We hope that in this article you have found a detailed answer to the question of what twilight is. It remains only to note that the duration of twilight in general and each of their periods in particular varies greatly, depending on the latitude at which they are observed.