Simple explanation

What is the sky?

The sky is infinity. For any people, the sky is a symbol of purity, because it is believed that God himself lives there. People referring to the sky, ask for rain, or the opposite of the sun. That is, the sky is not just air, the sky is a symbol of purity and impurity.

Sky - This is just the air, that ordinary air, which we have been breathing every second, one that cannot be seen and touch, because it is transparent and weightless. But we breathe something with transparent air, why does he take such a blue color over his head? Air contains several elements, nitrogen, oxygen, carbon dioxide, water pairs, various dust, which are constantly in motion.

In terms of physics

In practice, as physicists say, the sky is just air painted by sunlight. If it is easier to speak, the sun shines on the ground, but the sun's rays must go through a huge layer of air, which literally envelops the earth. And as the sunbeam has many colors, or rather seven rainbow colors. For those who do not know, it is worth recalling that seven colors of the rainbow is red, orange, yellow, green, blue, blue, purple.

Moreover, all these colors have every ray and he, passing through this layer of air, he splashes various colors of the rainbow in all directions, but the strongest of the blue color occurs, at the expense of which heaven also acquires a blue color. If you characterize briefly, then the blue sky is splashes that gives a ray painted in this color.

And on the moon

There is no atmosphere and therefore, the sky on the moon is not blue, but black. Cosmonauts that enter the orbit see the Black-Black Sky, which sparkles the planets and stars. Of course, the sky on the moon looks very beautiful, but still I would not want to see the black sky over your head.

Sky changes color

The sky is not always blue, it has a property to change color. Everything was probably noticed that sometimes it was whitish, sometimes Iscin-black ... Why so? For example, at night, when the sun does not sends his rays, we see the sky not blue, the atmosphere seems to us transparent. And through transparent air, a person can see the planets and stars. And in the afternoon, the blue color will again hide the mysterious space from an extraneous eye.

Various hypotheses Why blue sky? (Hypotheses Goethe, Newton, Scientists of the XVIII century, Rayleigh)

What hypotheses did not put forward at different times to explain the color of the sky. Watching the smoke on the background of a dark fireplace acquires a bluish color, Leonardo Da Vinci wrote: "... light flows on top of the darkness becomes blue, the more beautiful than the excellent and dark." Approximately the same point of view was adhered to Goettewho was not only a world famous poet, but also the largest scientist scientists of his time. However, such an explanation of the sky color turned out to be insolvent, since, as it became obvious later, the mixing of black and white can only give gray tones, and not colored. The blue color of smoke from the fireplace is determined by a completely different process.

After opening interference, in particular in thin films, Newtontried to apply the interference to the explanation of the color of the sky. To do this, he had to assume that water drops are of the form of thin-walled bubbles, like soaps. But since the droplets of the water contained in the atmosphere are actually spheres, then this hypothesis soon "burst" like a soap bubble.

Scientists of the XVIII century. Mariott, Buger, Euler Thought that the blue sky is explained by its own color of the components of the air. Such an explanation even received some confirmation later, already in the XIX century, when it was established that liquid oxygen has a blue color, and liquid ozone is blue. The closer to the correct explanation of the color of the sky approached OB. Sausure. He believed that if the air would be absolutely clean, the sky would be black, but the air contains impurities that reflect predominantly blue (in particular - water vapor and water droplets). To the second half of the XIX century. It has accumulated a rich experimental material on the scattering of light in liquids and gases, in particular one of the characteristics of the scattered light coming from the sky was discovered - its polarization. The first one opened it and explored Arago. It was in 1809. Later research of the polarization of the Heavenly Code was engaged in Babin, Brewster and other scientists. The question of the color of the sky so attracted the attention of scientists that the experiments on the scattering of light in liquids and gases that had much wider importance were carried out at the angle of view "Laboratory reproduction of the blue sky". This is also talking about the names of the work: "Modeling the blue sky "Trick or" about the blue sky color, the polarization of the light cloudy in general "Tindall. The successes of these experiments sent thoughts of scientists on the right track - to seek the cause of the blue sky in the scattering of sun rays in the atmosphere.

The first who created a slender, strict mathematical theory of molecular scattering of light in the atmosphere was an English Raleigh Scientist. He believed that the scattering of light was not at impurities, as his predecessors thought, and on the air molecules themselves. The first work of Rayleigh on the scattering of light was published in 1871. In the final form, its scattering theory, based on the electromagnetic nature of the light established by the time, was set out in the work "On the light from the sky, its polarization and color", published in 1899 for work in the field of light scattering Rayleigh (his full name John William Strett, Lord Railey III is often referred to as the Rayleigh dissipating, unlike his son, Lord Rayley IV. Rayleigh IV for a great contribution to the development of atmospheric physics is called Railen atmospheric. To explain the color of the sky, we give only one of the findings of the Rayleigh theory, to others we will also refer several times with the explanation of various optical phenomena. This conclusion reads: brightness, or intensity, scattered light changes inversely in proportion to the fourth degree of light wavelength falling on the scattering particle Thus, molecular scattering is extremely sensitive to the slightest change in the wavelength of the light. For example, the wavelength is violet. Ory rays (0.4 μm) are about two times less than the wavelength of red (0.8 microns). Therefore, the purple rays will be dissipated 16 times stronger than red, and with an equal intensity of the incident rays of them in the scattered light will be 16 times more. All other color rays of the visible spectrum (blue, blue, green, yellow, orange) will be part of the scattered light in quantities, inversely proportional to the fourth degree of wavelength of each of them. If now all color scattered rays mix in such a ratio, the color of the mixture of scattered rays will be blue.

Direct sunlight (i.e., the light coming directly from the solar disk), losing the scattering mainly blue and purple rays, acquires a weak yellowish shade, which is enhanced when the sun is lowering to the horizon. Now the rays have to take place in the atmosphere more and more way. On the long path of the loss of shortwave, i.e. violet, blue, blue, rays are becoming increasingly noticeable, and in the literal light of the sun or the moon reach the surface of the earth, they reach mostly long-wave rays - red, orange, yellow. Therefore, the color of the sun and the moon becomes yellow, then orange and red. Red Sun and Blue Sky Color This is two consequences of the same scattering process. Live, after he passes through the thickness of the atmosphere, remain predominantly long-wavelength rays (red sun), shortwave rays (blue sky) fall into the scattered light. So the theory of Rayleigh very clearly and convincingly explained the riddle of the blue sky and the Red Sun.

heaven Heat Molecular Scattering

Study and explanation

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Study and explanation. Sky colors. Project work performed Ruban Ksenia. Teacher physics I.A. Boyarin.

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Sky color Design work performed Ruban Ksenia. Teacher physics I.A. Boyar

Part of blue, and the horizon is whiten? Why the setting sun is usually red, and the sky over it is painted in different colors? To respond to these questions, you need to know how light interacts with molecules of atmospheric gases and with suspended particles. For some of these questions, unambiguous answers have not yet been received.

Considered the precursors of the weather. Such will take quite a lot and one time it was also considered that their study was the main task of atmospheric optics (section of the atmosphere physics, in which optical phenomena arising, with the passage of light in the atmosphere, and the color of the sky) are also studied.

Russian Geophysicist P.I. Brownov (20th century). Detailed studies have shown between optical and physical phenomena in the atmosphere of communication, exists. It became clear that it was possible to find a connection between optical phenomena and weather, studying the nature of optical phenomena and simultaneously penetrating the mechanism of physical phenomena causing changes in weather. Peter Ivanovich Brownov.

The sky color belongs to the 16th century Leonardo da Vinci explained the blue of the heavenly vault by the fact that white air on a dark background of world space seems blue.

Air particles have a bluish shade and in the total mass create an intense blue "At the beginning of the 18th century, Newton explained the color of the sky with a reflection of sunlight from the smallest droplets of water, always weighted in the air. L. Steeler Isaac Newton

The blue sky gave an English relay physicist (1871,1881).

The forming solar spectrum is dissipated by air molecules in proportion. Blue rays are dissipated, approximately 16 times stronger than red. Therefore, the color of the sky (scattered sunlight) is blue, and the color of the sun (direct sunlight), when it is low above the horizon and the rays go through a large path in the atmosphere - red. At the same time, the dissipated light should be strongly polarized, and at an angle of 90 degrees from the direction of the Sun, the polarization should be complete.

Why the sky is blue. Why the sun is yellow? These questions, such natural, arose before a person with deep antiquity. However, in order to obtain the right explanation of these phenomena, the efforts of outstanding scientists of the Middle Ages and later, up to the end of the XIX century were required.

What hypothesis existed? What hypotheses did not put forward at different times to explain the color of the sky. 1 hypothesis watching how smoke on the background of a dark fireplace acquires blue bats, Leonardo da Vinci wrote: ... Svetlota over darkness becomes blue, the more beautiful than the excellent and dark. "Approximately the same point of view held Goethe, which There was not only a world famous poet, but also the largest scientist nature tester of his time. However, such an explanation of the color of the sky turned out to be insolvent because, as it became obvious later, the mixing of black and white can only give gray tones, and not colored. Blue smoke color from the fireplace It is determined by a completely different process.

What hypothesis existed? 2 hypothesis After opening interference, in particular in thin films, Newton tried to apply interference to the explanation of the color of the sky. To do this, he had to assume that water drops are of the form of thin-walled bubbles, like soaps. But since the droplets of the water contained in the atmosphere are actually spheres, then this hypothesis soon burst "like a soap bubble.

What hypothesis existed? 3 hypothesis Scientists XVIII century. Mariott, Buger, Euler thought that the blue sky was explained by its own color of the components of the air. Such an explanation even received some confirmation later, already in the XIX century, when it was established that liquid oxygen has a blue color, and liquid ozone blue. O. B. Sosurur approached the correct explanation of the color of the sky. He believed that if the air had been absolutely clean, the sky would be black, but the air contains impurities that reflect predominantly blue (in particular water vapor and water droplets).

Results of the study: the first to create a slim, strict mathematical theory of molecular scattering of light in the atmosphere, was an English scientist Ralea. He believed that the scattering of light was not at impurities, as his predecessors thought, and on the air molecules themselves. To explain the color of the sky, we give only one of the findings of the Raylea theory:

Research results: The color of the mixture of scattered rays will be blue brightness, or intensity, scattered light changes inversely in proportion to the fourth degree of the wavelength of light falling on the scattering particle. Thus, molecular scattering is extremely sensitive to the slightest change in light wavelength. For example, the wavelength of purple rays (0.4 μm) is about two times less than the wavelength of red (0.8 microns). Therefore, the purple rays will be dissipated 16 times stronger than red, and with an equal intensity of the incident rays of them in the scattered light will be 16 times more. All other color rays of the visible spectrum (blue, blue, green, yellow, orange) will be part of the scattered light in quantities, inversely proportional to the fourth degree of wavelength of each of them. If now all color scattered rays mix in such a ratio, the color of the mixture of scattered rays will be blue

Lyiperad: S.V. Zvereva. In the world of sunshine., Hydrometeoisdat, 1988

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Playing on the street, I once drew attention to the sky, it was unusual: bottomless, endless and blue, blue! And only clouds slightly covered this blue color. I thought, why is the sky painted in a blue color? Immediately remembered the song of Fox Alice from the fairy tale about Pinocchio "What a blue sky ...!" And a geography lesson, where we, studying the topic "Weather" described the state of the sky, and also said that it is blue. So everything is why the sky is blue? Having come home, I asked this question to my mother. She told me that when people cry, they ask for help from the sky. The sky takes their tears, so it is like a lake, becomes blue. But Mom's story did not satisfy my question. I decided to find out from my classmates and teachers, do they know why the sky is blue? The questionnaire was attended by 24 student and 17 teachers. Processing the questionnaires, obtained the following results:

In school at the geography lesson, I asked the teacher. She answered me that the color of the sky can be easily explained from the point of view of physics. This phenomenon is called dispersion. From Wikipedia, I learned that the dispersion is the process of decomposition of light on the spectrum. Teacher on the geography of Larisa Borisovna invited me to blame this phenomenon by experimental. And we went to the Cabinet of Physics. Vasily Aleksandrovich, a physics teacher, I willingly agreed to help us. With the help of special equipment, I managed to trace how the dispersion process occurs in nature.

In order to find an answer to the question of why the sky is blue we decided to conduct a study. So the idea of \u200b\u200bwriting the project appeared. With my head, we defined the topic, purpose and objectives of the study, put forward a hypothesis, identified research methods and mechanisms for the implementation of our idea.

Hypothesis: The light on the ground sends the sun and most often when we look at him, it seems to us in a dazzling white. So the sky should be white? But in fact the sky is blue. In the course of the study, we will find explanations to these contradictions.

purpose: Find the answer to the question why the sky is blue and find out what its color depends on.

Tasks:1. Get acquainted with theoretical material on the topic

2. Experimentally study the dispersion phenomenon of light

3. Watch the sky at different times of the day and with different weather

Object of study: Sky

Thing: Sky light and color

Research methods: Analysis, experiment, observation

Stages of work:

1. Theoretical

2. Practical

3. Final: Conclusions on research

Practical value of work: Studies can be used in geography and physics lessons as an educational module.

2. The main part.

2.1. Theoretical aspects of the problem. Blue sky phenomenon in terms of physics

Why blue sky is very difficult to find an answer to such a simple question. First we give the definition of the concept. Sky - space above the ground or the surface of any other astronomical object. In general, the sky is usually called a panorama opening when looking from the surface of the Earth (or another astronomical object) in the direction of space.

Many scientists broke their heads in search of a response. Leonardo da Vinci, watching the fire in the fireplace, wrote: "The light flows on top of the darkness becomes blue." But today it is known that the merger of white and black gives gray.

Fig. 1. Hypothesis Leonardo da Vinci

Isaac Newton almost explained the color of the sky, however, for this he had to assume that the water drops contained in the atmosphere have thin walls like soap bubbles. But it turned out that these drops are spheres, which means they do not have wall thickness. So the soap bubble of Newton and burst!

Fig. 2. Newton hypothesis

The best solution to the problem about 100 years ago was offered by the English physicist Lord John Ralea. But start first. The sun radiates dazzling white light, which means the color of the sky should be the same, but it is still blue. What happens to white light in the atmosphere? He, passing through the atmosphere, as through the prism, disintegrates on seven colors. You are surely known these lines: every hunter wants to know where the Pheasant sits. These proposals hide a deep meaning. They represent us the basic colors in the spectrum of visible light.

Fig. 3. White light spectrum.

The best natural demonstration of this spectrum, of course, the rainbow.

Fig. 4 spectrum of visible light

Visible light is an electromagnetic radiation whose waves have a different length. There is not visible light, its eyes do not perceive. This is ultraviolet and infrared. We do not see it, because his length is either too large or too small. To see the light, it means to perceive his color, but what color we will see depends on the wavelength. The longest visible waves are red, and the shortest - purple.

From the wavelength, the ability of light to diffusion is also depends, that is, to distribute in the medium. Red light waves dissipate worse than all, but blue and purple colors have a high ability to dispel.

Fig. 5. The ability of light to dispersion

And finally, we came close to the answer to our question, and why the sky is blue? As mentioned above, white color is a mixture of all possible colors. When a collision with a gas molecule, each of the seven color components of white light dissipates. In this case, light with longer waves dissipates worse than light with short waves. Because of this, the air remains 8 times more than a blue spectrum than red. Although the shortest wave of purple color, the sky still seems blue due to mixing purple and green waves. In addition, our eyes perceive the blue color better than purple, with the same brightness of both. It is these facts that determine the color gamut of the sky: the atmosphere is literally filled with blue-blue rays.

However, the blue sky is not always. During the day we see the sky blue, blue, gray, in the evening - red (Attachment 1). Why the sunset is red? During sunset, the sun approaches the horizon, and the sunbeam is directed to the surface of the earth not vertically, as the day, and at an angle. Therefore, the path that he passes through the atmosphere is much longer that he passes during the day when the sun is worth high. Because of this, the blue-blue spectrum is absorbed in the atmosphere, not reaching the earth, and the longer light waves of the red spectrum reach the surface of the earth, painting the sky in red and yellow tones. The change in the color of the sky is clearly associated with the rotation of the Earth around its axis, which means the angle of falling light to the ground.

2.2. Practical aspects. Experimental solution to the problem

In the office of physics, I met the device spectrograph. Vasily Aleksandrovich, Teacher of Physics told me the principle of operation of this device, after which I independently spent the experience called dispersion. White light beam, passing through the prism, refracted and on the screen we see the rainbow (Appendix 2). This experience helped me understand how this amazing creature of nature appears in the sky. With the help of a spectrograph, scientists today can receive information about the composition and properties of various substances.

Photo 1. Demonstration of dispersion experience in

cabinet Physics

To get a rainbow I wanted me at home. My geography teacher, Larisa Borisovna told how to do it. An analogue of the spectrograph has become a glass container with water, a mirror, a flashlight and a white sheet of paper. We put a mirror in the container with water, we put a white sheet of paper behind the container. We direct on the mirror the light of the flashlight, so that the reflected light fell on the paper. A rainbow appeared on a sheet of paper! (Appendix 3). Experience is better to spend in a darkened room.

We have already spoken above that the white light in essence already contains all the colors of the rainbow. Make sure and collect all the colors back to white, you can make a rainbow top (Appendix 4).If it is strongly promoted, the colors will merge and the disk will get white.

Despite the scientific explanation of the formation of rainbow, this phenomenon remains one of the mysterious optical spectacles in the atmosphere. Watch and enjoy!

3. Conclusion

In search of an answer to so often asked parents Children's question "Why sky blue?" I learned a lot for myself interesting and instructive. Contradictions in our hypothesis today have a scientific explanation:

The whole secret in the sky in our atmosphere - in the air shell of the planet Earth.

White ray of the sun, passing through the atmosphere, disintegrates on the rays of seven colors.

Red and orange rays are the longest, and the blue are the shortest.

Blue rays less than others reach the Earth, and the sky turns out to be due to these rays permeated blue

The sky is not always painted in blue and it is connected with the axial movement of the Earth.

We managed to clearly imagine and understand how dispersion in nature occurs. At a class hour at school, I told my classmates why the sky has a blue color. It was also interesting to know where you can observe the dispersion phenomenon in our daily life. I found several practical applications of this unique phenomenon. (Appendix 5). In the future, I would like to continue to study the sky. How much does it be in yourself mysteries? What phenomena still occur in the atmosphere and, what are their nature? How do they affect the person and all living on earth? Perhaps this will be the topics of my future research.

Bibliography

1. Wikipedia - Free Encyclopedia

2. L.A. Malikova. Electronic physics manual "Geometric optics"

3. PRIRRYKIN A.V. Physics. Grade 9. Textbook. M.: Drop, 2014, p.202-209

4. HTT; / www. Voprosy-kak-IPochemu.ru.

5. Personal photo archive "Sky over Golyzhamanovo"

Attachment 1.

"Sky over Golyshmanovo"(Personal photo Archive)

Appendix 2.

Dispersion of light with a spectrograph

Appendix 3.

Light dispersion at home

"rainbow"

Appendix 4.

Rainbow top

Wolf in the state of resting the top in the process of rotation

Appendix 5.

Dispersion in man's life

Diamond lights on board aircraft

Headlights of a car

Reflective signs

But how many different colors exist, what does things surround us with color? And scientific knowledge of many such questions can already give an answer. For example, explain sky color.

To begin, it will be necessary to mention the great Isaac Newton, which observed the decomposition of white solar when it passes through the glass prism. What he saw is now called phenomenon dispersion, and the colorful painting itself - spectrum. The resulting colors exactly corresponded to the colors of the rainbow. That is, Newton watched the rainbow in the laboratory! It is due to his experiments at the end of the 18th century it was found that the white light is a mixture of different colors. Moreover, the same Newton proved that if the light decomposed into the spectrum again mix, then the white light will turn out. In the 19th century it was shown that light is spreading at a huge speed of 300,000 km / s electromagnetic waves. And at the beginning of the last century, these knowledge were supplemented by the idea of \u200b\u200ba quantum of light - photon. Thus, the light has a dual nature - both waves, and particles. This union and has become an explanation of many phenomena, in particular, the spectrum of thermal radiation of heated bodies. Such whom is ours.

After this entry, it's time to go to our topic. Blue sky color ... who did not admire them at least a couple of times in life! But is it just to say that all the blade the scattering of light in the atmosphere? And why then the color of the sky is not blue with the light of the full moon? And why is the blue color not the same on all sections of the sky? And what happens to the color of the sky when sunrise and sunset? After all, it can be yellow, and pink and even green. But still, this features of scattering. Therefore, consider it more.

The explanation of the color of the sky and its features belongs to the English physics of John William Raylej, who studied the scattering of light. It was he who pointed out that the color of the sky is determined by the dependence of scattering from the light frequency. The radiation of the Sun, falling into, interacts with gas molecules included in the air. And since the energy of the light quantum - the photon increases with a decrease in the length of the light wave, the most powerful effect on the gases molecules is more precisely on the electrons in these molecules, photons of the blue and purple part of the light spectrum are produced. Having come into forced oscillations, the electrons give back in the form of a photon of radiation taken from the light wave energy. Only these secondary photons are already emitted in all directions, and not only in the direction of the initial falling light. This will be the process of light scattering. In addition, you need to take into account the constant movement of air, and the fluctuation of its density. Otherwise, we would observe a black sky.

And now we return to the thermal radiation of the phone. The energy in its spectrum is unevenly distributed and described on the basis of laws established by the German physicist Wilhelm wine. The spectrum of our Sun will be the same uneven for the energies of photons. That is, photons of purple part of it will be much less than photons from the blue and the more blue. If you consider another physiology of vision, namely the maximum sensitivity of our eye to blue-green color, then we eventually get a blue or blue sky.

It should be noted that the longer the path of the solar beam in the atmosphere, the smaller it remains non-attending photons from the blue and blue field of the spectrum. Therefore, the color of the sky is uneven, and the morning or evening colors are yellow-red because of the large path of light through the atmosphere. In addition, dust, smoke, other particles contained in the air also strongly affect the scattering of light in the atmosphere. On this topic, you can recall the famous London pictures. Or memories of a catastrophe of 1883, which happened during the eruption of the volcanic Krakataau. The ashes from the eruption, which fell into the atmosphere, led to a bluish color of the Sun in many countries of the Pacific region, as well as the red dawns observed throughout the Earth. But these effects are already explained by another theory - scattering theory on particles commensurate with a light wavelength. This theory was offered to the world a German physicist Gustav Mi. The main idea of \u200b\u200bit is such particles due to their relatively large sizes, the red light is stronger, and not blue or purple.

Thus, the color of the sky is not just a source of inspiration for poets and artists, but a consequence of subtle physical laws that managed to reveal to human genius.