What a rainbow really is. A wonderful natural phenomenon - a rainbow-arc

Rainbow is one of the most magical and beautiful phenomena that we can observe in nature. When we were children, she would mesmerize us with her miraculous appearance literally out of nowhere and bright colors. It is so mysterious, but science has studied this phenomenon quite well. If you want to teach your children all about rainbows, you should read this article.

What is a rainbow?

A rainbow is a special phenomenon that occurs in nature when it is rainy on one side and sunny on the other. It consists of an arc that forms seven colors in the sky, namely violet, green, blue, orange, yellow, blue and red.

Remember the saying: “Every Hunter Wants to Know Where the Pheasant Sits”? Each word in this phrase begins with a letter representing one of the colors. Learn it with your children, they will find it very interesting. So, when sunlight, refracted, passes through tiny raindrops, a rainbow appears.

What is the mechanism of this phenomenon?

A simple explanation for the appearance of rainbows in the sky is that we usually see sunlight. White light that hits our planet from a huge star solar system- in fact, after which the system is named. Of course, this is the Sun. This light is made up of different colors, but as long as it moves in one direction, it appears white.

However, when it rains, millions of droplets cause the colors in white light to separate and refract through them. Each raindrop actually creates its own rainbow, but when there are many of them, the rainbow becomes large enough that we can see it with the naked eye.

Here are some interesting facts about rainbows:

We told you everything we knew about this phenomenon. Now you are armed with all sorts of interesting facts and are ready for any children's questions about rainbows. Even the trickiest ones.

RESEARCH WORK

Two people standing next to each other see their own rainbow! Because at every moment a rainbow is formed by the refraction of the sun's rays in more and more drops. Raindrops are falling. The place of the fallen drop is taken by another and manages to send its colored rays into the rainbow, followed by the next one and so on.

Prepared by: Yulia Polozova, Anastasia Stezhkina, Elena Khimina

Scientific supervisor: Olga Ivanovna Zaporozhtseva (physics teacher)

S. Losevo 2015

CONTENT

1. Introduction ……………………………………………………………………………………………….

2.What is a rainbow, history of research……………………………………………………………….

3. Rainbow in mythology and religion ………………………………………………………………………………………….

4.History of the study………………………………………………………………………………..

5.Physics of the rainbow…………………………………………………………………………………………

5.1.Where does a rainbow come from? Observation conditions……………………………………………………….

5.2.Why does a rainbow have the shape of an arc………………………………………………………..

5.3.Color of the rainbow and secondary rainbow………………………………………………………………

5.4.The cause of the rainbow is refraction and dispersion of light……………………………………………..

5.4.1.Newton’s experiments………………………………………………………………………………….

5.4.2. “Newton” in a drop………………………………………………………………………………………..

5.4.3. Scheme of rainbow formation ………………………………………………………………………………………

6.Unusual rainbows………………………………………………………………………………….

7.Rainbow and associated terms…………………………………………………………………………………

1. INTRODUCTION

Once, being in nature, we observed a rather beautiful phenomenon - a rainbow. The beauty of this phenomenon simply fascinated us. We came up with quite a few surveys, which we later formulated in our project.

Project goals:

Understand how a rainbow is formed.

Why does it always form at the same angle?

Why does a rainbow have an arc shape?

Rainbow: main and secondary. What is the difference?

Why is the name of Isaac Newton associated with the rainbow in the scientific world?

And so our research began.

2. WHAT IS A RAINBOW

A rainbow is not an object at all, but an optical phenomenon. This phenomenon occurs due to the refraction of light rays in drops of water, and all this occurs exclusively during rain. That is, a rainbow is not an object at all, but just a play of light. But what a beautiful game, I must say!

In fact, the arc familiar to the human eye is only part of a multi-colored circle. This is entirely a natural phenomenon can only be seen from an airplane, and even then only with a sufficient degree of observation

The first studies of the shape of the rainbow were carried out by the French philosopher and mathematician Rene Descartes back in the 17th century. To do this, the scientist used a glass ball filled with water, which made it possible to imagine how a sunbeam is reflected in a raindrop, refracting and thereby becoming visible.

To remember the sequence of colors in the rainbow (or spectrum) there are special simple phrases - the first letters in them correspond to the first letters of the names of colors:

TO akABOUT onceAND and to -Z lanternG tinWITH brokeF onar.

TO everyABOUT hunterAND wantsZ natG deWITH goesF azan

Remember them - and you can easily draw a rainbow at any time!

The first person to explain the nature of the rainbow wasAristotle . He determined that "a rainbow is an optical phenomenon, not a material object."

An elementary explanation of the phenomenon of the rainbow was given back in 1611 by A. de Dominie in his work “De Radiis Visus et Lucis”, then developed by Descartes (“Les météores”, 1637) and fully developed by Newton in his “Optics” (1750) .

The rainbow from one drop is weak, and in nature it is impossible to see it separately, since there are many drops in the curtain of rain. The rainbow that we see in the sky is formed by myriads of drops. Each drop creates a series of nested colored funnels (or cones). But from an individual drop only one colored ray hits the rainbow. The observer's eye is the common point at which the colored rays from many drops intersect. For example, all red rays coming out of different drops, but at the same angle and entering the observer's eye, form a red arc of the rainbow. All orange and other colored rays also form arcs. That's why the rainbow is round.

3. RAINBOW IN MYTHOLOGY AND RELIGION

People have long wondered about the nature of this most beautiful natural phenomenon. Humanity has associated the rainbow with many beliefs and legends. IN ancient greek mythology For example, a rainbow is the road between heaven and earth, along which the messenger between the world of the gods and the world of people, Iris, walked. In China, it was believed that the rainbow was a heavenly dragon, the union of Heaven and Earth. In Slavic myths and legends, the rainbow was considered a magical heavenly bridge from heaven to earth, a road along which angels descend from heaven to collect water from rivers. They pour this water into the clouds and from there it falls as life-giving rain.

Superstitious people believed that rainbows were a bad sign. They believed that the souls of the dead passed to the other world along a rainbow, and if a rainbow appeared, it meant someone’s imminent death.

Of course, since ancient times, people have tried to explain the rainbow. In Africa, for example, they believed that the rainbow was a huge snake that periodically crawled out of oblivion to carry out its dark deeds. However, intelligible explanations regarding this optical miracle could only be given towards the end of the seventeenth century. Then the famous Rene Descartes lived little by little. It was he who was first able to simulate the refraction of rays in a water drop. In his studies, Descartes used a glass ball filled with water. However, he could not fully explain the secret of the rainbow. But Newton, who replaced this very ball with a prism, managed to decompose a ray of light into a spectrum.

SUMMARY:

The rainbow is a bridge connecting (the world of people) and (the world of gods).

In ancient Indian - bow, god of thunder and lightning.

B is the road, messenger between the worlds of gods and people.

According to legends, the rainbow, like a snake, drinks water from lakes, rivers and seas, which then rains.

Hides a pot of gold in the place where the rainbow touched the ground.

According to legend, if you walk through a rainbow, you can change your gender.

The rainbow appeared later as a symbol of forgiveness for humanity, and is a symbol of the union (in Hebrew-Brit) of God and humanity (in the person of Noah) that there will never be a flood again. (Chapter Bereishit)

4. HISTORY OF RAINBOW RESEARCH

The Persian astronomer (1236-1311), and possibly his student (1260-1320), was apparently the first to give a fairly accurate explanation of the phenomenon.

The general physical picture of the rainbow was described in the book “De radiis visus et lucis in vitris perspectivis et iride”. Based on experimental observations, he came to the conclusion that a rainbow is produced as a result of reflection from the inner surface of a raindrop and double refraction - at the entrance to the drop and at the exit from it.

He gave a more complete explanation of the rainbow in the year in his work “Meteora” in the chapter “On the Rainbow”.

Although the multicolor spectrum of the rainbow is continuous, there are 7 colors in it. It is believed that the number 7 was chosen first, for which the number had a special meaning (for, or reasons). Moreover, initially he distinguished only five colors - red, yellow, green, blue and violet, which he wrote about in his “Optics”. But subsequently, trying to create a correspondence between the number of colors in the spectrum and the number of fundamental tones of the musical scale, Newton added to the five listed There are two more colors in the spectrum.

5. PHYSICS OF RAINBOW

5.1. Where does a rainbow come from? Observation conditions

Rainbows can only be seen before or after rain. And only if, simultaneously with the rain, the sun breaks through the clouds, when the sun illuminates the veil of falling rain and the observer is between the sun and the rain. What happens? The sun's rays pass through raindrops. And each droplet works like a prism. That is, it decomposes the white light of the Sun into its components - rays of red, orange, yellow, green, deep, blue and purple. Moreover, droplets deflect light of different colors in different ways, as a result of which white light decomposes into a multi-colored stripe, which is calledspectrum .

You can only see a rainbow if you are strictly between the sun (it should be behind you) and the rain (it should be in front of you). Otherwise you won't see the rainbow!

Sometimes, very rarely, a rainbow is observed under the same conditions when a rain cloud is illuminated by the moon. The same phenomenon of a rainbow is sometimes noticed when the sun illuminates water dust floating in the air near a fountain or waterfall. When the sun is covered with light clouds, the first rainbow sometimes seems completely uncolored and appears in the form of a whitish arc, lighter than the background of the sky; such a rainbow is called white.

Observations of the phenomenon of a rainbow have shown that its arcs represent regular parts of circles, the center of which always lies on a line passing through the observer’s head and the sun; because in this way the center of the rainbow is high standing sun lies below the horizon, the observer sees only a small part of the arc; At sunset and sunrise, when the sun is on the horizon, the rainbow appears as a semi-arc of a circle. From the top of very high mountains, from hot air balloon You can also see a rainbow in the form of most of the arc of a circle, since under these conditions the center of the rainbow is located above the visible horizon.

CONCLUSION: A rainbow appears only when suitable conditions are created for it. The sunshine should be shining at your back, and the raindrops should fall somewhere ahead. (Since bright sunlight is needed to form a rainbow, this means that the rain has already moved on or has completely passed by, and you are facing it.)

5.2. Why does a rainbow have an arc shape?

Why is the rainbow semicircular? People have been asking this question for a long time. In some African myths, a rainbow is a snake that envelops the Earth in a ring. But now we know that a rainbow is an optical phenomenon - the result of the refraction of light rays in water droplets during rain. But why do we see a rainbow in the form of an arc, and not, for example, in the form of a vertical stripe of color?

Here the law of optical refraction comes into force, in which a ray, passing through a raindrop located in a certain position in space, undergoes 42-fold refraction and becomes visible to the human eye precisely in the shape of a circle. This is exactly the part of this circle that you are used to observing.

The shape of a rainbow is determined by the shape of the water droplets in which sunlight is refracted. And water droplets are more or less spherical (round). Passing through the drop and being refracted in it, a beam of white sunlight is transformed into a series of colored funnels, inserted one into the other, facing the observer. The outer funnel is red, orange, yellow are inserted into it, then green, etc., ending with the inner violet. Thus, each individual drop forms a whole rainbow.

Of course, a rainbow from one drop is weak, and in nature it is impossible to see it separately, since there are many drops in the curtain of rain. The rainbow that we see in the sky is formed by myriads of drops. Each drop creates a series of nested colored funnels (or cones). But from an individual drop only one colored ray hits the rainbow. The observer's eye is the common point at which the colored rays from many drops intersect. For example, all red rays coming out of different drops, but at the same angle and entering the observer's eye, form a red arc of the rainbow. All orange and other colored rays also form arcs. That's why the rainbow is round.

The rainbow is a huge curved spectrum. To an observer on earth, a rainbow usually looks like an arc - part of a circle, and the higher the observer is, the fuller the rainbow. From a mountain or an airplane you can see the full circle!

It is interesting to note that two people standing next to each other and observing a rainbow each see it differently! All this is due to the fact that at each individual moment of viewing, a rainbow is constantly formed in new drops of water. That is, one drop falls, and another appears in its place. Also, the type and color of the rainbow depends on the size of the water droplets. The larger the raindrops, the brighter the rainbow will be. The most saturated color in the rainbow is red. If the droplets are small, the rainbow will be wider with a pronounced orange color at the edge. It must be said that we perceive the longest wave of light as red, and the shortest as violet. This applies not only to cases of observing a rainbow, but to everything in general. That is, you can now intelligently comment on the condition, size and color of the rainbow, as well as all other objects visible to the human eye.

Two people standing next to each other see their own rainbow! Because at every moment a rainbow is formed by the refraction of the sun's rays in more and more drops. Raindrops are falling. The place of the fallen drop is taken by another and manages to send its colored rays into the rainbow, followed by the next one and so on.

The appearance of the rainbow also depends on the shape of the drops. When falling in the air, large drops flatten and lose their sphericity. The stronger the flattening of the drops, the smaller the radius of the rainbow they form.

There is a group of optical phenomena called halo. They are caused by the refraction of light rays by tiny ice crystals in cirrus clouds and fogs. Most often, halos form around the Sun or Moon. Here is an example of such a phenomenon - a spherical rainbow around the Sun:

In fact, a rainbow is not a semicircle, but a circle. We just don’t see it in full, because the center of the rainbow’s circle lies on the same straight line with our eyes. For example, from an airplane you can see a full, round rainbow, although this happens extremely rarely, because on airplanes they usually look at their beautiful neighbors, or eat hamburgers while playing AngryBirds. So why is a rainbow shaped like a semicircle? This is because the raindrops that form a rainbow are clumps of water with a rounded surface. The light coming out of this very drop reflects its surface. That's the whole secret.

CONCLUSION: The appearance of the rainbow also depends on the shape of the drops. When falling in the air, large drops flatten and lose their sphericity. The stronger the flattening of the drops, the smaller the radius of the rainbow they form. The arc of a rainbow is just a segment of the circle of light, in the center of the viewing sector of which is the observer, that is, you. And the higher you stand, the fuller the rainbow will be

The appearance of the rainbow - the width of the arcs, the presence, location and brightness of individual color tones, the position of additional arcs - very much depend on the size of the raindrops. The larger the raindrops, the narrower and brighter the rainbow turns out. Large drops are characterized by the presence of a rich red color in the main rainbow. Numerous additional arcs also have bright colors and are directly adjacent to the main rainbows, without gaps. The smaller the droplets, the wider and fainter the rainbow becomes, with an orange or yellow edge. The additional arcs are further apart from each other and from the main rainbows. Thus, by the appearance of the rainbow one can approximately estimate the size of the raindrops that formed this rainbow.

5.3. Rainbow coloring and secondary rainbow

The color of the rainbow ring is determined by the refraction of sunlight in spherical raindrops, their reflection from the surface of the drops, as well as diffraction (from the Latin diffractus - broken) and interference (from the Latin inter - mutually and ferio - hitting) reflected rays of different wavelengths.

Sometimes you can see another, less bright rainbow around the first one. This is a secondary rainbow, in which the light is reflected twice in the drop. In a secondary rainbow, the order of colors is “inverted” - purple is on the outside and red is on the inside:

The inner, most often visible arc is colored red on the outer edge and violet on the inner edge; Between them, in the usual order of the solar spectrum, lie the colors (red), orange, yellow, green, blue and violet. The second, less frequently observed arc lies above the first, is usually more weakly colored, and the order of the colors in it is reversed. The part of the sky inside the first arc usually seems very light, the part of the sky above the second arc seems less light, and the annular space between the arcs seems dark. Sometimes, in addition to these two main elements of the rainbow, additional arcs are observed, representing weak colored blurry stripes bordering the upper part of the inner edge of the first rainbow and, less often, the upper part of the outer edge of the second rainbow

Sometimes you can see another, less bright rainbow around the first one. This is a secondary rainbow, in which the light is reflected twice in the drop. In the secondary rainbow, the order of colors is “inverted” - the outside is , and the inside is red. The angular radius of the secondary rainbow is 50-53°. The sky between two rainbows usually has a noticeably darker hue.

In the mountains and other places where it is very fresh air, a third rainbow can be observed (angular radius of about 60°).

The blurriness and blurriness of the colors of the rainbow is explained by the fact that the source of illumination is not a point, but an entire surface - the sun, and that individual sharper rainbows formed by individual points of the sun are superimposed on each other. If the sun shines through a veil of thin clouds, then the luminous source is the cloud surrounding the sun for 2 -3 ° and the individual color stripes overlap each other so much that the eye no longer distinguishes colors, but sees only a colorless light arc -white rainbow.

Since raindrops increase in size as they approach the ground, additional rainbows can be clearly visible only when light is refracted and reflected in high layers of the rain cover, that is, at a low altitude of the sun and only at the upper parts of the first and second rainbow. A complete theory of the white rainbow was given by Pörtner in 1897. The question has often been raised as to whether different observers see the same rainbow and whether a rainbow seen in the quiet mirror of a large reservoir of water is a reflection of a directly observed rainbow.

CONCLUSION: A rainbow occurs when the sun experiences water droplets slowly falling into. These droplets are different, as a result of which the light is decomposed into. It seems to us that a multi-colored glow emanates from space along concentric () lines. In this case, the source of bright light is always behind the observer. Later it was measured that it deviates by 137 30 minutes, and by 139°20’)

5.4.The cause of the rainbow is refraction and dispersion of light

Quite simply: Simply put, the appearance of a rainbow can be deduced into the following formula: light passing through raindrops is refracted. And it is refracted because water has a higher density than air. White color, as you know, consists of seven primary colors. It is quite clear that all colors have different wavelengths. And this is where the whole secret lies. When a ray of sunlight passes through a drop of water, it refracts each wave differently.

And now more details.

5.4.1. NEWTON'S EXPERIMENTS

Newton, while improving optical instruments, noticed that the image was colored rainbow around the edges. He was interested in this phenomenon. He began to explore it in more detail. Ordinary white light was passed through the prism, and on the screen a spectrum similar to the colors of the rainbow could be observed. At first Newton thought that it was the prism that colored White color. As a result of numerous experiments, it was possible to find out that the prism does not color, but separates the white color into a spectrum.

CONCLUSION: rays of different colors exit the prism at different angles.

5.4.2. “NEWTON” IN DROPS

When passing through raindrops, light is refracted (bent to the side) because water has a higher density than air. It is known that white color consists of seven primary colors - red, orange, yellow, green, blue, indigo and violet. These colors have different wavelengths, and the drop refracts each wave to a different degree when a ray of sunlight passes through it. Thus, waves of different lengths and, therefore, colors come out of the drop in slightly different directions. What was at first a single beam of rays is now scattered into its own natural colors, each traveling its own path.

Colored rays, hitting the inner wall of the drop and bending even more, can even exit through the same side that they entered. And as a result, you see how the rainbow scattered its colors across the sky in an arc.

Each drop reflects all colors. But from your fixed position on the earth, you only perceive certain colors from certain drops. The drops reflect the colors red and orange most clearly, so they reach your eyes from the very top drops. Blue and violet are reflected less well, so you see them from drops located slightly lower. Yellow and green reflect the drops that are in the middle. Put all the colors together and you get a rainbow.

5.4.3. RAINBOW FORMATION SCHEME

1) spherical,

2) internal,

3) primary rainbow,

4) ,

5) secondary rainbow,

6) incoming light beam,

7) the course of rays during the formation of the primary rainbow,

8) the course of rays during the formation of a secondary rainbow,

9) observer, 10-12) area of ​​rainbow formation.

Most often observedprimary rainbow , in which light undergoes one internal reflection. The path of the rays is shown in the figure at the top right. In the primary rainbow it is located outside the arc, its angular angle is 40-42°.

EXPLANATION FROM THE POINT OF PHYSICS

Observations of the rainbow have shown that the angle formed by two lines mentally drawn from the observer’s eyes to the center of the rainbow arc and to its circumference, or the angular radius of the rainbow, is an approximately constant value and equal to about 41° for the first rainbow, and 52° for the second. An elementary explanation of the phenomenon of the rainbow was given back in 1611 by A. de Dominie in his work “De Radiis Visus et Lucis”, then developed by Descartes (“Les météores”, 1637) and fully developed by Newton in his “Optics” (1750) . According to this explanation, the phenomenon of a rainbow occurs due to the refraction and total internal reflection (see Dioptrics) of the sun's rays in raindrops. If a ray SA falls on a spherical drop of liquid, then it (Fig. 1), having undergone refraction in the direction AB, can be reflected from the rear surface of the drop in the direction BC and exit, refracted again, in the direction CD.

The beam, otherwise falling on the drop, can, however, at point C (Fig. 2) be reflected a second time along CD and exit, refracted, in the direction DE.

If not one ray falls on a drop, but a whole bunch of parallel rays, then, as is proven in optics, all the rays that have undergone one internal reflection in a drop of water will come out of the drop in the form of a diverging cone of rays (Fig. 3), the axis of which is located along the direction of the incident rays. In reality, the beam of rays emerging from the drop does not represent a regular cone, and even all its constituent rays do not intersect at one point, only for simplicity in the following drawings these beams are taken to be regular cones with their apex in the center of the drop

The angle of the cone opening depends on the refractive index (see Dioptrics) of the liquid, and since the refractive index for rays of different colors (different wavelengths) that make up a white solar ray is not the same, then the angle of the cone opening will be different for rays of different colors, namely for there will be fewer purple ones than for red ones. As a result, the cone will be bordered by a colored rainbow edge, red on the outside, purple on the inside, and, if the drop is water, then half of the corner hole of the coneSOR for red it will be about 42°, for purple (SOV ) 40.5°. A study of the distribution of light inside the cone shows that almost all the light is concentrated in this colored border of the cone and is extremely weak in its central parts; Thus, we can only consider the bright colored shell of the cone, since all its internal rays are too weak to be perceived by vision.

A similar study of rays reflected twice in a drop of water will show us that they will come out with the same conical irisV"R" (Fig. 3), but red from the inner edge, purple from the outer, and for a water drop half of the angular hole of the second cone will be equal to 50° for red (SOR" ) and 54° for the purple edge (SOV ) .

Let us now imagine that an observer whose eye is at the pointABOUT (Fig. 4), looks at a row of vertical raindropsA, B , C, D, E... , illuminated by parallel sun rays moving in the directionSA, SB, SC etc.; let all these drops be located in a plane passing through the eye of the observer and the sun; each such drop will, according to the previous one, emit two conical light shells, the common axis of which will be the sun ray incident on the drop.

Let the dropIN located so that one of the rays forming the inner shell of the first (inner) cone will, when continued, pass through the eye of the observer; then the observer will see inIN purple dot. Somewhat higher than a dropIN a drop C will be located such that a ray coming from the outer surface of the shell of the first cone will enter the eye and give it the impression of a red dot inWITH ; drops in betweenIN AndWITH, will give the impression of blue, green, yellow and orange dots in the eye. In total, the eye will see in this plane a vertical rainbow line with a purple end at the bottom and a red end at the top; if we pass throughABOUT and the sun lineSO, then the angle formed by it with the lineOB , will be equal to the half-hole of the first cone for violet rays, i.e. 40.5°, and the angleCBS will be equal to the half-hole of the first cone for red rays, i.e. 42°. If you turn the cornerKOV aroundOK, ThatOB will describe a conical surface and each drop lying on the circle of intersection of this surface with the rain cover will give the impression of a light purple point, and all the points together will give a purple arc of a circle with a center atTO ; in the same way, red and intermediate arcs are formed, and in total the eye will receive the impression of a light rainbow arc, violet inside, red outside -first rainbow.

Applying the same reasoning to the second outer light conical shell emitted by drops and formed by solar rays reflected twice in a drop, we obtain a widersecond concentricrainbow with angleCFU, equal for the inner red edge - 50°, and for the outer purple edge - 54°. Due to the double reflection of light in the drops that produce this second rainbow, it will be significantly less bright than the first. DropsD, lying betweenWITH AndE, do not emit light at all into the eye, and therefore the space between two rainbows will appear dark; from the drops lying belowIN and higherE, white rays emanating from the central parts of the cones and therefore very weak will enter the eye; this explains why the space under the first and above the second rainbow appears dimly lit to us.

CONCLUSION:The elementary theory of the rainbow obviously indicates that different observers see rainbows formed by different raindrops, that is, different rainbows, and that the apparent reflection of a rainbow is the rainbow that would be seen by an observer placed under a reflecting surface at such a distance from it downwards, how he is above her. Observed in rare cases, especially at sea, intersecting eccentric rainbows are explained by the reflection of light from the water surface behind the observer and, thus, the appearance of two light sources (the sun and its reflection), each giving its own rainbow.- does not perceive). That's why a lunar rainbow looks whitish; but the brighter the light, the more “colorful” the rainbow will be, because In humans, bright light turns on the perception of color receptors -.

The center of the circle that a rainbow describes always lies on a straight line passing through (the Moon) and the observer’s eye, that is, it is impossible to see the sun and a rainbow at the same time without using mirrors. For an observer on the ground, it usually looks like part of a circle; the higher the point of view, the fuller the rainbow - from a mountain or an airplane you can see the whole .

A simple rainbow-arc is usually observed, but under certain circumstances you can see a double rainbow, and from an airplane - an inverted or even ring rainbow.

Ring Rainbow July 10, 2005

rainbow in the forest rainbow from an airplane

rainbow in the clouds rainbow over the sea

We are used to seeing a rainbow as an arc. In fact, this arc is only part of a multi-colored circle. This natural phenomenon can only be observed at high altitudes, for example, from an airplane.

There is a group of optical phenomena called halo. They are caused by the refraction of light rays by tiny ice crystals in cirrus clouds and fogs. Most often, halos form around the Sun or Moon. Here is an example of such a phenomenon - a spherical rainbow around the Sun: Iris resembles sectors of a rainbow

The rainbow also appears in many folk signs related to weather forecasting. For example, a rainbow that is tall and steep foreshadows good weather, and low and flat - bad.

8. LITERATURE USED

We have all repeatedly seen such an amazing and fascinating natural phenomenon - a rainbow. How does it arise, due to which a huge seven-color arc appears in the sky? Let's take a closer look at the essence of the rainbow as an atmospheric and natural phenomenon.

What is a rainbow as a natural phenomenon?

Rainbow is one of the most beautiful natural phenomena that is usually observed after rain. Rainbows are visible after rain because the sun illuminates many water droplets in the Earth's atmosphere. In shape, a rainbow is a semicircle or arc made up of seven colors of the spectrum - a multi-colored stripe. The higher the viewing point of a rainbow, the fuller and richer it is: for example, from the height of an airplane you can even see the full circle that the rainbow describes. There is one natural pattern: When you observe a rainbow arc, the sun is always behind you.

How and why does a rainbow appear?

A rainbow is primarily a physical phenomenon, which is based on the interaction of light and water. Sunlight is refracted and reflected by water droplets that float in the atmosphere. Drops reflect or deflect light in different ways. An observer who stands with his back to the sun (the source of light) sees a multi-colored glow in front of him. This is nothing more than white light, decomposing into a spectrum of seven colors: red, orange, yellow, green, blue, indigo, violet. But it should be noted that the rainbow, like many physical phenomena, has a peculiarity: seven colors are nothing more than an optical illusion, but in fact the spectrum is continuous, and its colors smoothly transform into each other through many intermediate shades.

Colors of rainbow

The colors of the rainbow are familiar to almost everyone thanks to the children's rhyme “Every hunter wants to know where the pheasant sits.” It is customary to talk about seven spectral colors: red, orange, yellow, green, blue, indigo and violet. However, the number of colors perceived by the eye also depends on the culture of a particular people and era. Let's look at how different peoples saw rainbow colors.

• For the Russian people, a rainbow is an arc of seven colors.
• For the British and Americans, a rainbow is six colors, since blue and blue are the same color in English.
• U Australian Aboriginals the rainbow corresponded with the six symbolic snakes.
• Some African tribes There are only two rainbow colors, or rather shades - light and dark.
• The great ancient Greek philosopher Aristotle identified only three primary colors: red, purple and green, and their combinations, in his opinion, gave the remaining colors.

You may also be interested in the following articles.

Article “Unusual in the ordinary. Rainbow"

Savostyanova Svetlana Anatolyevna, teacher of physics and mathematics, GAPOU MO "Egoryevsk Industrial and Economic College"
Description. I bring to your attention an educational article about rainbows. The article is written in the form of a story-conversation between a Dreamer, a Theorist, a Poet and an Artist. This material will be useful to schoolchildren, science teachers, and teachers of after-school groups. The article material can be used to prepare a message or report, conduct extracurricular activity, for the design of a thematic wall newspaper. The article is aimed at middle-level students (grades 5-8); partial use of the material is also possible for younger students.
Target: expanding schoolchildren's understanding of the rainbow.
Tasks:
- continue to develop knowledge about the optical phenomenon - the rainbow;
- develop cognitive interest;
- cultivate a sense of beauty, instill interest in the study of natural phenomena.

Dreamer.
Multi-colored arc
Hanging above the ground,
As if someone dropped it
A rocker from the sky.
(N. Silina)
What is this, guys? Rainbow! It would be great to drive or walk along it! They say you can’t... And why?
Theorist. Ozhegov’s dictionary gives the following definition: “A rainbow is a multi-colored arc in the firmament, formed as a result of the refraction of sunlight in raindrops. Colors of the rainbow (colors of the solar spectrum).” Unfortunately, you won't be able to walk on it.
Rainbow is a natural optical phenomenon. It provides a unique opportunity to observe the decomposition of white light into a spectrum in natural conditions. I'll tell you how a rainbow is formed.

It always occurs after rain. Somewhere between the Sun and the observer it is still raining. Sunlight, passing through drops of water, is repeatedly reflected and refracted in them, like in small prisms, and rays of different colors come out of the drops at different angles. If the raindrops are large (1-2 mm in diameter), then the rainbow is very bright, the stripes are clearly visible in it. If the drops are smaller, the rainbow appears faded and blurry. When the Sun rises above 42 degrees above the horizon, the rainbow is not visible from the Earth's surface. The sequence of color stripes is always the same: inside the arc there is a purple stripe, which first turns into blue, cyan, then green, yellow, orange and, finally, red, forming an arc with outside.
Poet. This amazing natural phenomenon has long been of interest not only to scientists, but also to poets. This is how Fyodor Tyutchev described the rainbow in his poem:
How unexpected and bright
In the damp blue sky,
Aerial arch erected
In your momentary celebration!
One end stuck into the forests,
Gone behind the clouds for others -
She covered half the sky
And she became exhausted at the height.

Oh, in this rainbow vision
What a treat for the eyes!
It is given to us for a moment,
Catch him - catch him quickly!
Look - it has already turned pale,
Another minute, two - and then what?
Gone, somehow gone completely,
What do you breathe and live by?
(August 5, 1865, Roslavl)
Dreamer. It is beautifully said, and indeed this phenomenon is observed for a short period of time. Is there anything else about rainbows?
Poet. This is how S. Petrushkov describes her appearance:
The rain has stopped, the storm has passed,
Rain dew glistens on the leaves.
Transparent puddles on clean paths -
Do not leave the house for a walk in sandals.
And in the sky, where the blue cloud hangs,
The beautiful rainbow is burning brightly!

Theorist. Guys, the decomposition of white light into a spectrum is called dispersion. Isaac Newton explained dispersion; he identified 7 colors in the spectrum, but this division is arbitrary. The colors blend smoothly into each other and have many shades. There are special phrases that allow us to correctly remember the order of the spectrum:
Every Hunter Wants to Know Where the Pheasant Sits!
How Brave Jean the Beller Knocked Down a Lantern with His Head!
Poet. Elena Blaginina in her poem “Rainbow” describes a seven-color rainbow this way, listing all its colors:
Rain, rain, don't rain, don't rain, wait!
Come out, come out, little golden bottom of the sun!
I'll run to admire the rainbow arc,
I’ll lie in wait for a seven-colored flower in the meadow.
I can’t look enough at the red arc,
Behind the orange, behind the yellow I see a new arc.
This new arc is greener than the meadows,
And behind her is a blue earring, like my mother’s.
I can’t get enough of the blue arc,
And behind this purple one,
I'll take it and run...
The sun set behind the haystacks. Where are you, rainbow-arc?
Theorist. Sometimes you can observe two, less often three, multi-colored arcs at once. The first rainbow is created by rays reflected once inside the drops, the second by rays reflected twice. Imagine, in 1948 in Leningrad, four rainbows appeared among the clouds over the Neva! And being on an airplane high above the ground, you can see a rainbow in the shape of a circle.

Dreamer. Why does a rainbow have an arc shape? Why is it not like the letter “P” in the sky, for example?
Theorist. The shape of a rainbow is determined by the shape of the water droplets in which sunlight is refracted. And water droplets ideally have a spherical shape. Of course, one drop will not give such a beautiful effect and the rainbow that we see is formed by a large number of droplets. At every moment, a rainbow is formed by the refraction of sunlight in new and new drops. Raindrops are falling. The place of the fallen drop is taken by another drop and manages to send its colored rays into the rainbow, followed by the next one, and so on. Besides, everyone sees their own rainbow!
Dreamer. Since I can’t walk, I’ll draw my own rainbow, especially not difficult, the main thing is to have colored pencils or paints and know the sequence of colors. Did anyone else besides me draw a rainbow?
Artist. Of course, Dreamer, even kids can draw rainbows. But you can also see a rainbow on the canvases of famous artists, because the rainbow motif is one of the favorites in the art of romanticism. It is present in the landscapes of many famous artists.

On some canvases it is a rainbow melting in the sky. There are dim colors, the rainbow is so subtle, ephemeral. On others it is like a monumental arch, like a support in a temple of nature. And somewhere it gives the landscape a fabulous quality and brightness.

Don't forget about her contemporary artists(the names of the artists, the paintings are located from right to left: Oksana Zbrutskaya, Kovalchuk, Joseph Abrisan, Elena Lukina).

Dreamer. Indian sages said: “Don’t look for miracles, there are none. Seek knowledge - it is there. And everything that people call miracles is one degree or another of knowledge.”. Today we know what a rainbow is and how it is formed. But I still want to call this amazingly beautiful natural phenomenon a miracle. And I am a little bit, but I continue to believe that where the rainbow goes one end into the ground, you can dig up a pot of gold.
The arch of the rainbow is the creator's favor,
It combines air, moisture, light -
Everything without which there is no life for the world.
He is a wondrous vision in a black cloud
Shows us...
(Ivan Bunin, Rainbow, 1922)

Literature
1. Pavlenko Yu.G. The beginnings of physics: Textbook - M.: Publishing house "Exam", 2007.
2. Encyclopedia for children. T.8. Astronomy - M.: Avanta +, 1998.

1. Introduction.

Rainbow is one of the most beautiful natural phenomena. One day, while walking after the rain, I saw a rainbow in the sky. I was delighted with what I saw. And questions immediately began to arise: how is such beauty obtained, and is it possible to do all this at home in order to see this amazing miracle again?

A rainbow occurs due to the refraction (change in angle) of sunlight in water droplets in the air.

It looks like an arc made up of the colors of the spectrum - red, orange, yellow, green, blue, indigo and violet

Goal of the work:Try to reproduce and experimentally obtain a rainbow at home, find practical applications of the rainbow in life.

Task: find out the reason for the appearance of a rainbow,

study the definition of the word “rainbow” in different dictionaries.

learn the colors and order of the rainbow

get a rainbow at home.

Learn the practical applications of spectrum.

Object of study is a natural phenomenon of the rainbow.

Subject of study– the concept of “rainbow” as a natural phenomenon.

Hypotheses:

The appearance of a rainbow only on a sunny day after rain.

You can get a rainbow if you replace the sun's rays with an artificial light source.

2. The meaning of the word rainbow in dictionaries.

1) encyclopedic Dictionary

Rainbow- a multi-colored arc in the sky. Observed when the Sun illuminates a curtain of rain located on the opposite side of the sky from it. Explained by the refraction, reflection and diffraction of light in raindrops.

2) Ozhegov's Explanatory Dictionary

Rainbow- a multi-colored arc on the vault of heaven, formed due to the refraction of sunlight in raindrops. Colors of the rainbow (colors of the solar spectrum).

3) Character dictionary

Rainbow - Meanstransformation, heavenly glory, different states of consciousness, the meeting of Heaven with Earth, a bridge or border between the world and paradise, the throne of the God of Heaven. The celestial serpent is associated with the rainbow, since it can also be a bridge between two worlds. Besides, in traditional symbolism For the French, Africans, Indians and American Indians, the rainbow is a snake quenching its thirst in the sea.

4) Encyclopedia of Brockhaus and Efron

Rainbow is a well-known optical phenomenon in the atmosphere; observed whenthe sun illuminates the veil of falling rain and the observer is between the sun and the rain. This phenomenon appears in the form of one, or less often, two concentric light arcs, drawn in the sky from the direction of falling rain and colored concentrically in a series of “rainbow” colorsov.

5) Bible Encyclopedia

Rainbow - (arc in a cloud) - majestica natural phenomenon occurring from the refraction of light rays in raindrops. It usually happens during rain, when the sun is shining, and on the opposite side of it there is a cloud from which it's raining. A rainbow is a brilliant arc-shaped stripe, painted with all the colors of the solar spectrum, with violet occupying the lower edge of the arc and red occupying the upperedge.

6) Dictionary Ushakova

Rainbow - R "ADUGA, rainbows, female. Multi-colored archeda ribbon in the sky during rain, formed due to the refraction of sunlight in water droplets. Seven colors of the rainbow. "The uneven glass of the windows shimmers with the colors of the rainbow." A. Turgenev. | Spectrum, seven-color stripeformed by the refraction of light rays in a prism.

3 . The history of rainbow research by scientists.

The Persian astronomer Qutb al-Din al-Shirazi (1236-1311), and perhaps his student Kamal al-Din al-Farizi (1260-1320), was apparently the first to give a fairly accurate explanation of the phenomenon.

The general physical picture of the rainbow was described in 1611 by Mark Antony de Dominis in the book "De radiis visus et lucis in vitris perspectivis et iride". Based on experimental observations, he came to the conclusion that a rainbow is produced as a result of reflection from the inner surface of a raindrop and double refraction - at the entrance to the drop and at the exit from it.

René Descartes gave a more complete explanation of the rainbow in 1635 in his work Meteora in the chapter "On the Rainbow."
Although the multicolor spectrum of the rainbow is continuous, according to tradition, it is divided into 7 colors. It is believed that Isaac Newton was the first to choose the number 7, for whom the number 7 had a special symbolic meaning. Moreover, initially he distinguished only five colors - red, yellow, green, blue and violet, which he wrote about in his “Optics”. But later, trying to create a correspondence between the number of colors of the spectrum and the number of fundamental tones of the musical scale, Newton added two more to the five listed colors of the spectrum.

In 1637, the famous French philosopher and scientist Descartes gave a mathematical theory of the rainbow based on the refraction of light. Subsequently, this theory was supplemented by Newton based on his experiments on the decomposition of light into colors using a prism. Descartes' theory, supplemented by Newton, could not explain the simultaneous existence of several rainbows, their different widths, the obligatory absence of certain colors in color stripes, the influence of the size of cloud drops on appearance phenomena. The exact theory of the rainbow, based on ideas about the diffraction of light, was given in 1836 by the English astronomer George Airy. Considering the veil of rain as a spatial structure that ensures the occurrence of diffraction, Airy explained all the features of the rainbow. His theory has fully retained its significance for our time.

4. Mnemonic phrases

The colors in the rainbow are arranged in a sequence corresponding to the spectrum of visible light. Exist mnemonic phrases to remember this sequence. In these phrases, the initial letter of each word corresponds to the initial letter of the name of a certain color. The colors in the phrase are listed according to the order of the colors in the rainbow, from red (longest wavelength visible light) to violet (shortest wavelength visible light).

1. TO every O hunter and wants h nah, G de With goes f azan

2. TO ak O once AND ak- h lantern G tin With broke f onar.

3. TO mouth O anyway, and Irafu, h Ike G got along well With tare f Ufaiki.

4. TO every O shaper and wants h nah, G de With sway f Photoshop.

5. Making a rainbow at home.

You can get a rainbow at home using such experiments.

1. A rainbow created by dipping a mirror into water.

Materials used: Container with water, mirror light source (lamp, sunlight), sheet white cardboard.

I place a mirror in a container of water at an angle of about 25 degrees to the surface of the water. Place a sheet of white cardboard nearby. We direct the light source to the mirror, as a result of the refraction of the ray in water and its reflection from the mirror on a sheet of cardboard, a rainbow appears.

2. Rainbow with a CD.

Materials used: CD, light source (lamp, sunlight).

We direct the light source at an angle of about 25 degrees to the surface of the CD. A rainbow will appear on the surface of the CD as a result of refraction.

3. Rainbow in soap bubbles .

. Practical application of the spectrum.

Spectral analysis.

The phenomenon of dispersion is used in science and technology in the form of a method for determining the composition of a substance, called spectral analysis. This method is based on the study of light emitted or absorbed by a substance.

Spectral analysis is a method of studying chemical composition substance, based on the study of its spectra.

Spectral apparatus is used to obtain and study spectra. The simplest spectral devices are a prism and a diffraction grating. More accurate ones are a spectroscope and a spectrograph.

Using spectral analysis, it is possible to detect this element in the composition of a complex substance, even if its mass is extremely small.

The main areas of application of spectral analysis are: physical and chemical research; mechanical engineering, metallurgy; nuclear industry; astronomy, astrophysics; forensics. Modern technologies The creation of new building materials (metal-plastic, plastic) is directly related to such fundamental sciences as chemistry and physics. Data science uses modern methods substance research. Therefore, spectral analysis can be used to determine the chemical composition of building materials from their spectra.

7. Conclusion.

A rainbow is one of the most amazing and beautiful natural phenomena. Based on the above and based on the experiments I have done, we can say that a rainbow can be reproduced at home and enjoy its beauty at any time. I also learned how the rainbow is used, or rather the decomposition of light into spectra, and how important it has become in human life.

I believe that the goal of my work has been achieved, the tasks set at the beginning of the project have been completed, and the hypotheses have been confirmed experimentally.