The emerald sunset is a miracle of physics. Green rays of the sun

Phenomenon observation

To observe the green beam, three conditions are necessary: an open horizon (in the steppe, tundra, mountains or at sea in the absence of excitement), fresh air and the cloud-free side of the horizon where the Sun sets or rises. Observation with the naked eye is rare. Using a spyglass, a telescope, binoculars, and pointing the device at the sunrise point in advance, you can see it on almost any day with suitable weather. You can watch no more than a few seconds - dangerous! At sunset, its bright light does not allow the use of optics at all.

The normal duration of the green beam is only a few seconds. You can significantly increase the time of its observation if, when it appears, you quickly run up the embankment or move from one deck of the ship to another at such a speed as to maintain the position of the eye relative to the green beam. During one of the expeditions to the South Pole, the American pilot and explorer Richard Byrd observed the green beam for 35 minutes. This happened at the end of the polar night, when the edge of the solar disk first appeared above the horizon and moved along it (when viewed from the pole, the solar disk moves almost horizontally: its ascent rate is very small).

Physics of the phenomenon

As a result of the superposition of color rays from individual points of the solar disk, the central part of it will remain white (or rather, due to scattering, the entire disk becomes red), and only the upper and lower edges of the disk are in a predominant position. The top becomes blue-green, the bottom becomes orange-red. The red and orange parts of the Sun's disk set below the horizon before the green and blue parts.

atmospheric dispersion sun rays in the most obvious form it manifests itself at the very last moment of sunset, when a small upper segment remains above the horizon, and then only the very “top” of the solar disk. The last ray of the setting Sun, decomposing into a spectrum, forms a "fan" of colored rays. Divergence of extreme rays visible spectrum- violet and red - averages 38 ", but with stronger refraction it can be much more. When the Sun sinks below the horizon, we should have seen violet with the last beam. However, the shortest wavelengths - violet, blue, blue - on a long way in the atmosphere (when the Sun is already at the horizon), they are scattered so much that they do not reach earth's surface. In addition, the human eye is less sensitive to the rays of this part of the spectrum. Therefore, at the last moment of sunset, the last ray of the setting Sun turns out to be a bright emerald color. This phenomenon is called green beam .

At sunrise, the reverse color change takes place. The first ray of the rising Sun is green; then yellow, orange, and finally red are added to it, together forming the normal daylight of the Sun.

The phenomenon of the green ray comes in three forms:

in the form of a green edge of the upper part of the solar disk,
as a green segment
in the form of a green beam, which looks like a green flame escaping from the horizon.

blue and red beam

With exceptionally high air transparency, the last beam can be green-blue and even blue. Similar phenomenon observed extremely rarely.

It is also extremely rare to observe a "red beam". The red beam appears at the moment when the lower edge of the solar disk appears under the clearly formed edge of the cloud covering the rest of the disk. At the same time, the height of the Sun above the horizon should be minimal, and the air should be completely transparent. The physics of the phenomenon is similar to the physics of the green beam described above.

In culture

Jules Verne's novel The Green Ray (1882) is dedicated to this natural phenomenon.
Mentioned in the book by Leonid Sobolev "Green Ray" about patrol boats of the Black Sea Fleet during the Great Patriotic War
In the third part of the film "Pirates of the Caribbean" the green beam, according to Mr. Gibbs, appears when the soul returns from the underworld to the world of the living.
In the story "Interns" by the Strugatsky brothers.
French director Eric Romer directed the film The Green Ray (1986).

Notes

Source

S. V. Zvereva. In the world sunlight. L., Gidrometeoizdat, 1988, 160 pages with ill.

Links

Andrew T. Young An Introduction to Green Flashes. San Diego State University. Department of Astronomy. - one of the most complete English-language sites dedicated to the phenomenon of the green ray. Archived
Les Cowley Green Flash (English) . Atmospheric Optics. Archived from the original on October 23, 2012. Retrieved October 20, 2012.
mario cogo Green Flash Gallery. Galaxy Lux. Astrophotography by Mario Cogo. Archived from the original on October 23, 2012. Retrieved October 20, 2012.

Wikimedia Foundation. 2010 .

See what the "Green Ray" is in other dictionaries:

Flash of green light at the moment of disappearance of the solar disk under the horizon (usually sea) or its appearance from behind the horizon. The phenomenon is extremely rare, associated with the refraction of sunlight in the atmosphere. * * * GREEN BEAM GREEN BEAM, flash… … encyclopedic Dictionary

green beam- flash Green colour at the moment of the disappearance of the solar disk behind the horizon (usually sea) or its appearance from the horizon. It is observed in nature extremely rarely, only in very clear air. Lasts a few seconds. The phenomenon is associated with... Marine Biographical Dictionary

green beam- žalio pluoštas statusas T sritis radioelektronika atitikmenys: engl. green beam vok. grünes Bundel, n; Strahl fur Grün, m rus. green beam, m; green beam, m pranc. faisceau vert, m … Radioelectronics terminų žodynas

A flash of green light above the Sun's disk at sunset, observed for several seconds at the moment when the upper edge of the Sun's disk disappears below the horizon. Origin Z. l. due to the refraction of sunlight in the atmosphere. Great Soviet Encyclopedia

Flash of green light at the moment of the disappearance of the solar disk under the horizon (usually sea) or its emergence from the horizon. The phenomenon is extremely rare, associated with the refraction of sunlight in the atmosphere ... Natural science. encyclopedic Dictionary

green beam- A phenomenon observed (usually in the open sea, ocean) at the moment of sunset, disappearing behind the horizon, in the form of a flash (bunny, ray, spot) of green or, less often, blue color. E. Green ray D. Grüner Strahl, grüner Lichtstrahl … Explanatory UFO dictionary with equivalents in English and German

Phenomenon observation

To observe the green beam, three conditions are necessary: an open horizon (in the steppe, tundra, mountains or at sea in the absence of waves), clean air and a cloud-free side of the horizon where the sunset or sunrise occurs. Observation with the naked eye is rare. Using a spyglass, a telescope, binoculars, and pointing the device at the sunrise point in advance, you can see it on almost any day with suitable weather. You can watch no more than a few seconds - dangerous! At sunset, its bright light does not allow the use of optics at all.

Physics of the phenomenon

Atmospheric dispersion of solar rays manifests itself most clearly at the very last moment of sunset, when a small upper segment remains above the horizon, and then only the very “crown” of the solar disk. The last ray of the setting Sun, decomposing into a spectrum, forms a "fan" of colored rays. The divergence of the extreme rays of the visible spectrum - violet and red - averages 38 ", but with stronger refraction it can be much larger. When the Sun sinks below the horizon, we should see violet with the last beam. However, the shortest wavelengths are violet, blue, blue - on a long journey in the atmosphere (when the Sun is already at the horizon), they scatter so much that they do not reach the earth's surface. In addition, the human eye is less sensitive to the rays of this part of the spectrum. Therefore, at the last moment of sunset, the last ray of the setting Sun turns out to be a bright emerald color.This phenomenon is called green beam .

At sunrise, the reverse color change takes place. The first ray of the rising Sun is green; then yellow, orange, and finally red are added to it, together forming the normal daylight of the Sun.

The phenomenon of the green ray comes in three forms:

in the form of a green edge of the upper part of the solar disk,
as a green segment
in the form of a green beam, which looks like a green flame escaping from the horizon.

blue and red beam

With exceptionally high air transparency, the last beam can be green-blue and even blue. Such a phenomenon is extremely rare.

In culture

Jules Verne's novel The Green Ray (1882) is dedicated to this natural phenomenon.
Mentioned in the book by Leonid Sobolev "Green Ray" about patrol boats of the Black Sea Fleet during the Great Patriotic War
In the third part of the film "Pirates of the Caribbean" the green beam, according to Mr. Gibbs, appears when the soul returns from the underworld to the world of the living.
In the story "Interns" by the Strugatsky brothers.
French director Eric Romer directed the film The Green Ray (1986).

Notes

Source

S. V. Zvereva. In the world of sunshine. L., Gidrometeoizdat, 1988, 160 pages with ill.

Links

Andrew T. Young An Introduction to Green Flashes. San Diego State University. Department of Astronomy. - one of the most complete English-language sites dedicated to the phenomenon of the green ray. Archived
Les Cowley Green Flash (English) . Atmospheric Optics. Archived from the original on October 23, 2012. Retrieved October 20, 2012.
mario cogo Green Flash Gallery. Galaxy Lux. Astrophotography by Mario Cogo. Archived from the original on October 23, 2012. Retrieved October 20, 2012.

Wikimedia Foundation. 2010 .

Raid on Baalbek
Raid on Tyre

See what the "Green Ray" is in other dictionaries:

green beam- a flash of green light at the moment of the disappearance of the solar disk under the horizon (usually sea) or its appearance from behind the horizon. The phenomenon is extremely rare, associated with the refraction of sunlight in the atmosphere. * * * GREEN BEAM GREEN BEAM, flash… … encyclopedic Dictionary

green beam- a flash of green color at the moment of the disappearance of the solar disk behind the horizon (usually sea) or its appearance from the horizon. It is observed in nature extremely rarely, only in very clear air. Lasts a few seconds. The phenomenon is associated with... Marine Biographical Dictionary

green beam- a flash of green light over the disk of the Sun at sunset, observed for several seconds at the moment when the upper edge of the solar disk disappears below the horizon. Origin Z. l. due to the refraction of sunlight in the atmosphere. Great Soviet Encyclopedia

GREEN RAY- a flash of green light at the moment of the disappearance of the solar disk under the horizon (usually sea) or its appearance from the horizon. The phenomenon is extremely rare, associated with the refraction of sunlight in the atmosphere ... Natural science. encyclopedic Dictionary

green beam- A phenomenon observed (usually in the open sea, ocean) at the time of sunset, disappearing over the horizon, in the form of a flash (bunny, ray, spot) of green or, less commonly, blue. E. Green ray D. Grüner Strahl, grüner Lichtstrahl … Explanatory UFO dictionary with equivalents in English and German

green beam- an optical phenomenon, a flash of green light at the moment the solar disk disappears below the horizon (usually sea) or appears from behind the horizon.

"Have you ever observed the Sun setting below the horizon of the sea? Yes, without a doubt. Have you followed it until the moment when the upper edge of the disk touches the horizon and then disappears? Probably yes. But have you noticed the phenomenon what happens at the moment when the luminous luminary throws its last ray, if the sky is cloud-free and completely transparent? a color such that no artist can obtain on his palette and that nature itself does not reproduce, either in the various shades of vegetation, or in the color of the most transparent sea.

An article in an English newspaper from Jules Verne's novel "The Green Beam"

Such a note brought the young heroine of Jules Verne's novel "The Green Ray" into an enthusiastic state and prompted her to undertake a series of journeys with the sole purpose of seeing with her own eyes green beam. The young Scot failed, as the novelist relates, to observe this beautiful phenomenon nature. But it still exists. The green beam is not a legend, although there is a lot of legend associated with it. This is a phenomenon that every nature lover can admire if he searches for it with due patience. Why does the green beam appear?
You will understand the cause of the phenomenon if you remember in what form objects appear to us when we look at them through a glass prism. Do this experiment: hold the prism near the eye horizontally with the wide side down and look through it at a piece of paper pinned to the wall. You will notice that the leaf, firstly, has risen much higher than its true position, and secondly, it has a violet-blue border at the top, and a yellow-red one at the bottom. The rise depends on the refraction of light, the colored borders depend on the dispersion of the glass, i.e. the properties of glass do not refract rays equally different color. Violet and blue rays are refracted more strongly than others, so we see a violet-blue border at the top; red ones are refracted the weakest, and therefore the lower edge of our paper sheet has a red border.

For a better understanding of what follows, it is necessary to dwell on the origin of these colored borders. The prism decomposes the white light emanating from the paper into all the colors of the spectrum, giving many color images of a paper sheet, arranged, partly superimposed on one another, in the order of refraction. From the simultaneous action of these superimposed. on top of each other color images of the eye gets a feeling white color(the addition of spectral colors), but rims of immiscible colors protrude at the top and bottom.

The famous poet Goethe, who did this experiment and did not understand its meaning, imagined that he had thus exposed the falsity of Newton's doctrine of colors, and then wrote his own "Science of Flowers", which is almost entirely based on false ideas.

The earth's atmosphere is for our eyes like a huge air prism, turned base down. Looking at the Sun at the horizon, we look at it through a gas prism. The disk of the Sun receives a border of blue and green at the top, and red-yellow at the bottom. As long as the Sun is above the horizon, the light of the disk interrupts much less bright colored stripes with its brightness, and we do not notice them at all. But at the moments of sunrise and sunset, when almost its entire disk is hidden under the horizon, we can see the blue border of the upper edge. It is two-tone: above is a blue stripe, below - blue, from a mixture of blue and green rays. When the air near the horizon is completely clear and transparent, we see a blue border - the "blue ray". But more often the blue rays are scattered by the atmosphere and only one green border remains: the "green ray" phenomenon. Finally, in most cases, blue and green rays are also scattered by the cloudy atmosphere - then no border is noticed: the Sun sets in a crimson ball.

Pulkovo astronomer G. A. Tikhov, who devoted a special study to the "green ray", reports some signs of the visibility of this phenomenon. " If the Sun is red at sunset and easy to look at with a simple eye, it is safe to say that no green light"The reason is clear: the red color of the solar disk indicates a strong scattering of blue and green rays by the atmosphere, i.e., the entire upper rim of the disk. "On the contrary, - the astronomer continues, - if the Sun has changed little from its usual whitish-yellow color and sets very brightly(i.e., if the absorption of light by the atmosphere is small. - Ya. P.), then it is possible with highly likely wait for the green light. But here it is just important that the horizon be a sharp line, without any irregularities, nearby forest, buildings, etc. These conditions are best met at sea; that is why the green beam is so well known to sailors."

So, to see the "green beam", you need to observe the Sun at the time of sunset or sunrise with a very clear sky. AT southern countries the sky near the horizon is more transparent than ours, so the phenomenon of the "green beam" is observed there more often. But in our country it is not as rare as many people think, probably under the influence of Jules Verne's novel. The persistent search for the "green ray" is sooner or later rewarded with success. It happened to capture this beautiful phenomenon even with a telescope. Two Alsatian astronomers describe such an observation as follows:
"... In the last minute before sunset, when, therefore, a noticeable part of it is still visible, the disk, which has a wavy moving, but sharply defined border, is surrounded by a green rim. Until the Sun has completely set, this rim is not visible to the naked eye. It becomes visible only at the moment of complete disappearance of the Sun behind the horizon. strong increase(about 100 times), you can trace in detail all the phenomena: the green border becomes noticeable at the latest 10 minutes before sunset; she limits upper part disk, while a red border is observed from the bottom. The width of the rim, initially very small (only a few seconds of arc), increases as the Sun sets; it sometimes reaches up to half a minute of the arc. Above the green rim, green protrusions are often observed, which, with the gradual disappearance of the Sun, seem to slide along its edge to the highest point; sometimes they break away from the rim and glow separately for several seconds until they go out "Usually, the phenomenon lasts a second or two. But under exceptional circumstances, its duration noticeably lengthens. A case was noted when the" green beam "was observed for more than 5 minutes! The sun was setting behind a distant mountain, and the fast-paced observer saw the green border of the solar disk, as if sliding along the side of the mountain.

Very instructive are the cases of observing the "green beam" at sunrise, when the upper edge of the luminary begins to appear from under the horizon. This refutes the often expressed conjecture that the "green beam" is an optical illusion that the eye succumbs to when weary of the bright brilliance of the Sun that has just set.

A beam like an emerald, The key of golden happiness - I will still get it, My green weak beam ... N. Zabolotsky

I bet that each of us has repeatedly seen the red sky at sunset. Its characteristic color is due to the refraction and scattering of sunlight in the Earth's atmosphere. However, few people have ever seen such an amazing sight - green sunset. This natural event can be observed when the horizon is far away and the air is crystal clear. In most cases, the green beam can be seen only for a moment above the water surface of the sea or ocean, and only sometimes - in the mountains. His appearance in middle lane Ukraine is an extremely rare event and is possible only with successful combination a large number favorable factors. The author of this photo managed to observe and photograph the green beam.

Basically, the lucky ones who had the opportunity to see this are sailors. They believe that his appearance - good omen, a sign of a successful completion of the journey. People believed that the one who saw the green beam would find his happiness. Bright flashes of blue-green color, at the edge of the Sun, leave indelible impressions and memories for a lifetime.

Skeptics consider the green beam to be fiction or an optical illusion. Some believe that this is the reaction of the human eye, tired of contemplating the sun. It is for the latter that the famous popularizer of science Ya. I. Perelman in his book " Entertaining physics not only explains in detail the reason natural phenomenon"green ray", but also cites facts that refute various misconceptions about this. And in our time, when photographic technology makes it possible to capture numerous cases of the appearance of a green beam, doubts seem to have to leave the skeptics.

Causes of this extraordinary spectacle easy to explain based on the knowledge gained in high school . It is known that sunlight consists of a set of electromagnetic waves, each of which has its own frequency and length. A wave of a certain frequency is perceived by the human eye as a color: red, orange, yellow, green, blue, indigo and violet (every hunter wants to know where the pheasant is sitting). Red color has the largest wavelength in this spectrum, which is about 0.7-0.6 micrometers. For green and purple flowers the wavelength is approximately 0.5 and 0.4 micrometers, respectively. Despite such seemingly small differences in wavelength, rays of different colors propagate differently in matter, in particular, they have different speeds. The dependence of the speed of light waves in a substance on their length or frequency is a manifestation of a more general dependence of the speed of the response of a substance to the oscillation frequency electric field in a light wave. In physics, this phenomenon is called dispersion. In most substances and environments, including the earth's atmosphere, red light propagates at a higher speed than blue-green. This dependence, called normal dispersion, corresponds to lower refractive indices for red light than for blue-green. Recall that the refractive index is a value showing how much the speed of light in a substance v is less than in vacuum: n = c/v, where c ≈ 3 108 m/s is the speed of light in vacuum.

And if you also know law of refraction of light, everything is generally simple. According to this law, with an oblique incidence of light on the boundary of media with different refractive indices, the light beam deviates from the original direction of propagation, that is, it is refracted. When a light beam hits from a region with a smaller value of n, for example, from a vacuum, where n = 1, into a medium with great value n the angle of refraction is always less than the angle of incidence. Recall that both angles are counted from the normal (perpendicular) to the interface between the regions. Since the refractive indices for waves of different lengths are different, the angles of refraction will also be different, namely: red light will be refracted less than green. This, in particular, is the reason for the decomposition of white light into a spectrum when it is passed through a glass prism. A similar decomposition of sunlight into a spectrum takes place in the Earth's atmosphere. However, it is only observed in individual cases and in special places. So, at sunset or sunrise, its rays, visible to an observer on Earth, fall obliquely from outer space (vacuum). Since the density of the atmosphere increases as you approach the surface of the Earth, the refractive index of light also increases. Light, propagating from space to the earth's surface, is constantly refracted, and therefore decomposed into a spectrum, and, as in a glass prism, the rays of red light are refracted least of all. Although the difference in the refractive indices for red and blue-green light rays in the atmosphere is extremely small, but at large distances (hundreds of kilometers), the effect of their separation is quite observable. This is precisely the reason for the appearance of the green beam. Indeed, while the sun is already really below the horizon and its red rays pass above the observer, the shorter wavelength green rays, which are more deflected, can be seen. Of course, blue, blue and violet rays, which have an even shorter wavelength, are refracted much more strongly, but it is almost impossible to see them: they are very strongly scattered and absorbed in the earth's atmosphere.

The main obstacle to observing the green beam- scattering on suspended particles of fog, dust, smoke and other terrestrial air pollution, as well as on atmospheric inhomogeneities. In addition, as already mentioned, the length of the path of sunlight from the point of entry into the Earth's atmosphere to the point of observation must be sufficiently large. All these conditions are most easily fulfilled when observing sunset or sunrise on large water areas. It is almost impossible to see a green beam in the steppe or in a wooded area. Even understanding all the physical causes and the natural origin of the green ray, it is difficult to get rid of a strong emotional impact. Therefore, like sailors and poets, I would like to believe that the appearance of this miracle of nature will serve as a good omen for the country and the people living in it.

Doctor of Physical and Mathematical Sciences V. TIMOSHENKO.

A beam like
emerald,
golden happiness
key -
I'll still get it
My green
weak light...
N. Zabolotsky

Each of us has repeatedly seen how the sun disk disappears behind the horizon in the red sunset sky. The characteristic color of a sunset is due to the refraction and scattering of sunlight in the Earth's atmosphere (see "Science and Life" No. 9, 1993). However, few people know about another optical phenomenon that also occurs at sunset and is associated with the propagation of light in the earth's atmosphere - the appearance of a green beam. This unique natural event can be observed when the horizon is far away and the air is crystal clear. In most cases, the green beam can be seen only for a moment above the water surface of the sea or ocean, and only sometimes - in the mountains. Its appearance in central Russia is an extremely rare event and is possible only with a successful combination of a large number of favorable factors. The author of this article managed to observe and photograph a green beam on the Volga, in the region of Nizhny Novgorod.

Most often, sailors observed the green beam during long voyages and believed that its appearance was a good omen, a sign of a successful completion of the journey. People believed that those who were lucky to see the green ray would find their happiness. There is a legend, retold by Jules Verne in the novel "The Green Ray", according to which "he who at least once is lucky enough to see the green beam will become the owner of an invaluable treasure, whose name is "heart insight." And then the person will not be afraid of any delusions and illusions for he will be able to read without difficulty in his own heart and in the hearts of others." The bright blue-green colors of the flash at the edge of the Sun leave indelible impressions and memories for a lifetime. They inspired the poet Nikolai Zabolotsky, who observed a green ray on the Baltic Sea, to write a poem, a stanza from which is taken as an epigraph to this article.

Skeptics consider the green beam to be fiction or an optical illusion. Some believe that this is the reaction of the human eye, tired of contemplating the sun. It is for the latter that the famous popularizer of science Ya. I. Perelman in his book "Entertaining Physics" not only explains in detail the cause of the natural phenomenon "green ray", but also cites facts that refute various misconceptions about this. But only in our time, when photographic technology makes it possible to capture numerous cases of the appearance of a green beam, it seems that doubts should leave the skeptics.

The reasons for the occurrence of this extraordinary spectacle can be easily understood based on the knowledge gained in high school. It is known that sunlight consists of a set of electromagnetic waves, each of which has its own frequency and length. A wave of a certain frequency is perceived by the human eye as a color: red, orange, yellow, green, blue, indigo and violet (every hunter wants to know where the pheasant is sitting). Red color has the largest wavelength in this spectrum, which is about 0.7-0.6 micrometers. For green and violet colors, the wavelength is approximately 0.5 and 0.4 micrometers, respectively. Despite such seemingly small differences in wavelength, rays of different colors propagate differently in matter, in particular, they have different speeds. The dependence of the speed of light waves in a substance on their length or frequency is a manifestation of a more general dependence of the speed of the response of a substance to the frequency of oscillations of the electric field in a light wave. In physics, this phenomenon is called dispersion. In most substances and environments, including the earth's atmosphere, red light propagates at a higher speed than blue-green. This dependence, called normal dispersion, corresponds to lower refractive indices for red light than for blue-green. Recall that the refractive index is a value showing how much the speed of light in a substance v is less than in vacuum: n = c/v, where c ≈ 3 10 8 m/s is the speed of light in vacuum.

The second thing that is necessary for understanding the phenomenon is the knowledge of the law of refraction of light. According to this law, with an oblique incidence of light on the boundary of media with different refractive indices, the light beam deviates from the original direction of propagation, that is, it is refracted. When a light beam hits from a region with a smaller value of n, for example, from a vacuum, where n = 1, into a medium with a larger value of n, the angle of refraction is always less than the angle of incidence. Recall that both angles are measured from the normal (perpendicular) to the interface between the regions. Since the refractive indices for waves of different lengths are different, the angles of refraction will also be different, namely: red light will be refracted less than green. This, in particular, is the reason for the decomposition of white light into a spectrum when it is passed through a glass prism. A similar decomposition of sunlight into a spectrum takes place in the Earth's atmosphere. However, it is observed only in individual cases and in special places. So, at sunset or sunrise, its rays, visible to an observer on Earth, fall obliquely from outer space (vacuum). Since the density of the atmosphere increases as you approach the surface of the Earth, the refractive index of light also increases. Light, propagating from space to the earth's surface, is constantly refracted, and therefore decomposed into a spectrum, and, as in a glass prism, the rays of red light are refracted least of all. Although the difference in the refractive indices for red and blue-green light rays in the atmosphere is extremely small, but at large distances (hundreds of kilometers), the effect of their separation is quite observable. This is precisely the reason for the appearance of the green beam. Indeed, while the sun is already really below the horizon and its red rays pass above the observer, the shorter wavelength green rays, which are more deflected, can be seen. Of course, blue, blue and violet rays, which have an even shorter wavelength, are refracted much more strongly, but it is almost impossible to see them: they are very strongly scattered and absorbed in the earth's atmosphere.

The main obstacle to observing the green beam is scattering on suspended particles of fog, dust, smoke and other terrestrial air pollution, as well as on atmospheric inhomogeneities. In addition, as already mentioned, the length of the path of sunlight from the point of entry into the Earth's atmosphere to the point of observation must be sufficiently large. All these conditions are most easily met when observing a sunset or sunrise over large expanses of water. It is almost impossible to see a green beam in the steppe or in a wooded area. The fact that this phenomenon could be observed on the Volga, in central Russia, is most likely due to exceptionally favorable weather conditions, as well as good choice time and place of observation. It happened at the very beginning of May, when, due to the late spring, mass flowering of plants had not yet begun. The weather was clear and cool, the air was clean and transparent. I was on the Volga embankment, just behind the place where the Oka flows into it, behind the so-called arrow. From this point, the Volga is visible for a long distance upstream.

Even understanding all the physical causes and the natural origin of the green ray, it is difficult to get rid of a strong emotional impact. Therefore, like sailors and poets, I would like to believe that the appearance of this miracle of nature over the Volga, in the very heart of Russia, will serve as a good omen for the country and the people living in it.