What is a rainbow? Why a rainbow appears A message on the topic of natural phenomena rainbow.

The answer is known: it is a multi-colored band in the form of an arc, which sometimes appears against the background of the sky. A rainbow is an optical, atmospheric, and weather phenomenon at the same time. It occurs when the air is saturated with tiny drops of water and light passes through them.


This happens after or during rain, fog or in clear weather near a raging river, fountain, watering machine.

Why is the rainbow colored?

A rainbow is made up of rays of light. Where does their color come from? We see white light. In fact, sunlight is made up of particles that vibrate at different frequencies. Her brain (thanks to the eyes) and distinguishes as colors. For example, we perceive rays with a high frequency of oscillation as red, with a low frequency as violet. In the general stream, rays of different frequencies are mixed, and the light appears white.

When it passes through drops of water hanging in the air, it changes direction - it is refracted. Moreover, its different rays are refracted at different angles: red at a small, and, say, purple - at a large angle. And at the exit from the drops, the "white" light breaks up into a spectrum - rays with different colors. We see them as rainbows.

A similar picture is obtained when a film of gasoline shimmers in different colors on a puddle or a soap bubble.

Why is the rainbow not always visible after the rain?

In order for a visible rainbow to be born, it is necessary that the stream of light be strong enough. On cloudy days, you won't see rainbows.


In this case, the light should be in front of the eyes, and not behind the head. Usually some people see a rainbow, while others - at the same time as the first - do not see it. Why? If the sun is with your back, then you will see the light before it has passed through the drops and played with the spectrum.

When the sun is too high, its rays, after refraction, do not enter the eyes. The higher the sun, the smaller the rainbow arc. Therefore, the rainbow is not visible at noon, but more often it is observed in the morning or in the evening.

But when you go up (for example, up the stairs), more and more light rays enter the eyes, and the rainbow grows. And the passengers of a flying airliner see through the windows not a rainbow arc, but a full circle!

How many colors are in a rainbow?

No need to smile - the question is not as stupid as it seems.

Of course, we are used to the fact that there are seven of these colors, but this is a tribute to tradition. It comes from Isaac Newton. In experiments, he showed where the spectrum comes from. The great scientist counted five colors in the rainbow - red, yellow, green, blue and violet. However, he did not like the number very much.

Seven was considered a magic number (seven days of the week, seven wonders of the world, seventh heaven, seven deadly sins, etc.). “Looking closely” at the rainbow, Newton added two shades to the spectrum - orange and indigo (blue-violet), and there were seven colors.


But the ancient Russians were sure that there were only four colors in it - scarlet, blue, green and crimson. The Japanese see the rainbow as six colors - they consider green to be a variety of blue. In short, among different peoples, the number of rainbow colors ranges from nine to two (light and dark).

It makes no sense to ask how many of them "really" - the colors of the spectrum imperceptibly pass into each other and you can conditionally divide it into as many bands as you like.

How to remember the order of the colors in the rainbow?

Well, it's quite easy. We remember them by the first letters of the words in a simple phrase: "Every hunter wants to know where the pheasant sits"(red, orange, yellow, green, blue, indigo, violet). There are also modern version: “Every designer wants to know where to download Photoshop.

The English phrase about "pheasant" looks shorter: Run off you girls - boys in view("Run, girls - the boys have appeared").

There is a better option: Richard of York gave battle in vain("Richard of York fought in vain"). Pay attention to the set of colors: red, orange, yellow, green, blue, indigo, violet - the British have kept "indigo"! What can you do, in their language, blue and blue colors are denoted the same way.

How to get a rainbow at home?

You will not be able to see a full-fledged rainbow from floor to ceiling. But still…

1. Take a CD, put it in sunlight and change the angle. So it is easy to get bright iridescent spots, stripes or a circle around its edge on the disk.


2. On a sunny day, place a bowl of water on a windowsill or table by the window. Place a mirror at the bottom. Taking it in your hand, move it and the mirror so that the stream of rays reflected by the mirror hits the paper. The light from it, passing through the layer of water, will decompose into a spectrum. A piece of the rainbow will appear on the paper.

All of us have repeatedly seen such an amazing and bewitching phenomenon of nature - a rainbow. How does it arise, due to which a huge seven-color arc appears in the sky? Let us consider in more detail 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, which is customary to observe after rain. A rainbow is visible after rain because the sun illuminates many water droplets in the Earth's atmospheric layer. The shape of the rainbow is a semicircle or arc, composed of seven colors of the spectrum - a multi-colored stripe. The higher the point of observation of the 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 regularity: 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 based on the interaction of light and water. Sunlight is refracted and reflected by water droplets that float in the atmosphere. Droplets reflect or deflect light differently. An observer who stands with his back to the sun (light source) sees a multi-colored glow in front of him. This is nothing but white light, decomposed 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 but an optical illusion, in fact, the spectrum is continuous, and its colors smoothly transition 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 is sitting." 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, the rainbow is six colors, since blue and blue in English are the same color.
• At Australian aborigines the rainbow was associated with six symbolic snakes.
• Some African tribes allocate only two iridescent colors, or rather, shades - light and dark.
• The great ancient Greek philosopher Aristotle singled out only three primary colors: red, purple and green, and their combinations, in his opinion, gave the rest of the colors.

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Introduction 3

Chapter 1. Literary analysis on research topic 5

1.1. The historical aspect of the study of topic 5

1.2. Basic concepts of the problem under study 6

1.3. Characteristics of rainbow species 9

Chapter 2. Experimental part 11

2.1. Methodology of experimental work 11

2.2. Results of experimental work 14

Conclusion 17

References 18

Appendix 1. 19

Appendix 2. 21

Annex 3. 22

Appendix 4. 26

Annex 5. 28

Introduction

Relevance.

Probably, there is no person who would not admire the rainbow. This magnificent colorful phenomenon in the sky has long attracted everyone's attention. She was considered a good harbinger, attributed to her magical properties. Everyone knows that a rainbow can have magical properties only in fairy tales, but in reality a rainbow is an optical phenomenon associated with the refraction of light rays on numerous raindrops. However, not everyone knows exactly how a rainbow is formed. When and how can you see it? Is it possible to experimentally study a rainbow? How to get an artificial rainbow? These and many other questions are answered in this work.

Object of study: natural phenomenon - rainbow.

Subject of study: ways to get a rainbow.

I put forward the following hypothesis: using different laboratory setups, you can get an artificial rainbow and explore it physical properties in laboratory conditions.

Purpose of my research: reveal the physical properties of the rainbow and experimentally test methods for its production in the laboratory.

I achieved my goal by solving tasks:

collect information about the methods of obtaining, properties and types of rainbows;

design laboratory facilities for obtaining a rainbow and test them at home;

analyze the theoretical and practical results of their work.

Research stages:

collect information about the types and properties of the rainbow (ask your parents, read in a book, find it on the Internet);

select experimental work on obtaining an artificial rainbow;

construct laboratory facilities for obtaining an artificial rainbow;

to conduct an experiment;

compare the theoretical and practical results of obtaining an artificial rainbow;

arrange research work;

prepare a report and presentation for the defense of the work.

Methods and techniques: observation, experiment, analysis.

Chapter 1. Literary analysis on the research topic

1. 1. The historical aspect of the study of the topic

In Russian chronicles, the rainbow is called the "paradise arc" or abbreviated as "raiduga". IN Ancient Greece the rainbow was personified by the goddess Irida (“Irida” means “rainbow”). According to the ideas of the ancient Greeks, the rainbow connects heaven and earth, and Irida was the mediator between the gods and people. Rainbow is a physical phenomenon. 8

The rainbow is always associated with rain. It can appear before the rain, and during the rain, and after it, depending on how the cloud moves, giving heavy rainfall.

The first attempt to explain the rainbow as a natural phenomenon was made in 1611 by Archbishop Antonio Dominis. His explanation of the rainbow was contrary to the biblical one, so he was excommunicated and sentenced to death penalty. Antonio Dominis died in prison without waiting for execution, but his body and manuscripts were burned. 8

The scientific explanation of the rainbow was first given by Rene Descartes in 1637. Descartes explained the rainbow on the basis of the laws of refraction and reflection of sunlight in drops of falling rain. At that time, dispersion had not yet been discovered - the decomposition of white light into a spectrum upon refraction. Therefore, Descartes' rainbow was white.

30 years later, Isaac Newton, who discovered the dispersion of white light upon refraction, supplemented Descartes' theory by explaining how colored rays are refracted in raindrops. 3

Despite the fact that the Descartes-Newton theory of the rainbow was created more than 300 years ago, it correctly explains the main features of the rainbow: the position of the main arcs, their angular dimensions, the arrangement of colors in rainbows of various orders.

1. 1. Basic concepts of the problem under study

An ordinary rainbow is a colored arc with an angular radius of 42°, visible against the background of a curtain of heavy rain or rainfall streaks, often not reaching the Earth's surface. The rainbow is visible in the side of the sky opposite the Sun, and always with the Sun not covered by clouds. The center of the rainbow is a point diametrically opposite to the Sun, the antisolar point. The outer arc of the rainbow is red, followed by orange, yellow, green arcs, etc., ending with the inner purple. 2

The fact is that a more or less spherical drop, illuminated by a parallel beam of rays of sunlight, can form a rainbow only in the form of a circle.

How many rays of a rainbow are there in a beam of light falling on a drop? There are many of them, in fact, they form a whole cylinder. The locus of the points of their fall on the drop is a whole circle.

As a result of passing through the drop and refraction in it, the cylinder of white rays is transformed into a series of colored funnels inserted one into the other. The outer funnel is red, orange is inserted into it, yellow, then comes green, etc., ending with the inner violet. 4

The size and shape of the droplets and their effect on the appearance of the rainbow

The type of rainbow - the width of the arcs, the location and brightness of color tones, the position of additional arcs are very dependent on the size of the raindrops. By the appearance of a rainbow, one can approximately estimate the size of the raindrops that formed this rainbow. The larger the raindrops, the narrower and brighter the rainbow. Especially characteristic of large drops is the presence of a rich red color in the main rainbow. The smaller the droplets, the wider and fainter the rainbow, with an orange or yellow edge. Additional arcs are further apart both from each other and from the main rainbows. 8

The type of rainbow also depends on the shape of the drops. When falling in the air, large drops are flattened and lose their sphericity. The vertical cross section of such drops approaches an ellipse.

Is it possible to see the whole circle of the rainbow? From the surface of the Earth, a rainbow can be observed at best in the form of a half circle when the Sun is on the horizon. When the sun rises, the rainbow goes below the horizon. From an airplane or a helicopter, you can observe a rainbow in the form of a whole circle. 8

Calculations according to the formulas of the diffraction theory, performed for drops of different sizes, showed that the whole form of the rainbow - the width of the arcs, the presence, location and brightness of individual color tones, the position of additional arcs very strongly depend on the size of the raindrops. Here are the main characteristics appearance rainbows for drops of different radii. 5

Drop radius 0.5—1 mm. The outer edge of the main rainbow is bright, dark red, followed by light red, and then all the colors of the rainbow alternate. Violet and green seem especially bright. There are many additional arcs (up to five), they alternate purple-pink tones with green. Additional arcs are directly adjacent to the main rainbows.

Droplet radius 0.25 mm. The red edge of the rainbow has become weaker. The rest of the colors are still visible. Several purple-pink additional arcs are replaced by green ones.

Drop radius 0.10—0.15 mm. There is no more red in the main rainbow. The outer edge of the rainbow is orange. The rest of the rainbow is well developed. Additional arcs become increasingly yellow. Gaps appeared between them and between the main rainbow and the first additional one.

Drop radius 0.04—0.05 mm. The rainbow became noticeably wider and paler. Its outer edge is pale yellow. The brightest is purple. The first additional arc is separated from the main rainbow by a fairly wide gap, its color is whitish, slightly greenish and whitish-violet.

Droplet radius 0.03 mm. The main rainbow is even wider with a very faintly colored slightly yellowish edge, contains separate white stripes.

The droplet radius is 0.025 mm or less. The rainbow is completely white. It is about twice as wide as an ordinary rainbow and has the appearance of a shiny white stripe. Inside it there may be additional colored arcs, first pale blue or green, then whitish red. 1

Thus, by the appearance of the rainbow, one can approximately estimate the size of the raindrops that formed this rainbow. In general, the larger the raindrops, the narrower and brighter the rainbow, especially for large drops is the presence of saturated red in the main rainbow. Numerous additional arcs also have bright colors and directly, without gaps, adjoin the main rainbows. The smaller the droplets, the wider and faded the rainbow with an orange or yellow edge. Additional arcs are further apart both from each other and from the main rainbows.

The type of rainbow also depends on the shape of the drops. When falling in the air, large drops are flattened and lose their sphericity. The vertical cross section of such drops approaches an ellipse. Calculations have shown that the minimum deviation of red rays when passing through flattened drops with a radius of 0.5 mm is 140°. Therefore, the angular size of the red arc will not be 42°, but only 40°. For larger droplets, such as a radius of 1.0 mm, the minimum deviation of the red rays will be 149°, and the red arc of the rainbow will have a size of 31° instead of 42°. Thus, the stronger the flattening of the drops, the smaller the radius of the rainbow they form. 7

1. 1. Characteristics of rainbow species

Are there rainbows without rain, or without rain streaks? They happen in the lab. Artificial rainbows were created as a result of the refraction of light in a single suspended drop of distilled water, water with syrup, or clear oil. Droplet sizes varied from 1.5 to 4.5 mm. Heavy drops were elongated under the action of gravity, and their cross section was an ellipse. When the droplet was illuminated by a beam of a helium-neon laser, not only the first and second rainbows appeared, but also the unusually bright third and fourth, centered around the light source (in this case, the laser). Sometimes it was possible to receive even the fifth and sixth rainbows. These rainbows, like the first and second, were again in the direction opposite to the source. True, these rainbows were monochromatic, red, since they were formed not by a white light source, but by a monochromatic red beam. 8

misty rainbow

White rainbows are found in nature. They appear when sunlight illuminates a faint fog, consisting of droplets with a radius of 0.025 mm or less. They are called foggy rainbows. In addition to the main rainbow in the form of a brilliant white arc with a barely noticeable yellowish edge, sometimes colored additional arcs are observed: a very faint blue or green arc, and then a whitish red.

A similar kind of white rainbow can be seen when a spotlight behind you illuminates an intense haze or faint fog in front of you. Even a street lamp can create, albeit a very faint, white rainbow visible against the dark background of the night sky. 6

moon rainbows

Like solar rainbows, lunar rainbows can also occur. They are weaker and appear during the full moon. Lunar rainbows are rarer than solar rainbows. For their occurrence, a combination of two conditions is necessary: ​​the full moon, not covered by clouds, and the fallout of heavy rain or streaks of its fall (not reaching the Earth).

Rainbows formed by moon rays are not iridescent and look like light, completely white arcs. The lack of red color in lunar rainbows, even with large raindrops, is explained low level illumination at night, in which the sensitivity of the eye to red rays is completely lost. The remaining color rays of the rainbow also lose their color tone to a large extent due to the lack of color in human night vision. 8

Chapter 2. Experimental part 2.1. Methodology of experimental work

To obtain a rainbow in the laboratory, there are many methods and techniques, we used the following in our work:

Experience 1. Rainbow in a basin.

Equipment and materials: glass container; water; mirror.

Progress:

On a sunny day, fill a large glass container with water. Then dip the mirror into the water. Move this mirror and find a position where a rainbow forms on the walls of the room. You can fix the position of the mirror. Let the water calm down so that the rainbow is more distinct, and then draw or photograph the rainbow as you see it.

Equipment and materials: glass container; water; mirror; White list paper; flashlight.

Progress:

On a sunny day, fill a large glass container with water. Then dip the mirror into the water. Move this mirror and find a position where a rainbow forms on the walls of the room. You can fix the position of the mirror. Let the water calm down so that the rainbow is more distinct. Additionally, put a sheet of white paper in front of a basin of water and a mirror, direct the light of a flashlight to the part of the mirror immersed in water, a rainbow will appear on a sheet of paper. Then draw or photograph the rainbow the way you saw it.

Experience 3. Rainbow in a box.

Equipment and materials: cardboard box; stationery knife; CD type CD-R; plastic tube; glue; flashlight; candle; Fluorescent Lamp.

Progress:

Take a large cardboard box. In its side wall, cut a vertical slot a few centimeters high and 3 to 5 millimeters wide. It will give the stream of light the shape of a thin strip extending in a vertical plane. Place a blank CD-R on the opposite wall of the box.

Now cut a hole in the side wall of the box for a tube to observe the spectrum. Although the tube has round section, the hole must be oval so that it can be rotated in a horizontal plane.

Insert the tube into the hole. Aim the slit at the light source. Look into the tube, and by turning it, find the spectrum and examine it.

Try observing with a spectroscope the spectra of various light sources: the sun, an incandescent lamp, a fluorescent lamp, a candle, LEDs of different colors.

Spectra obtained with a spectroscope can be photographed with a webcam or digital camera.

Equipment and materials: a sheet of plywood, a knife, a flashlight, a sheet of white paper, a CD, pencils, a camera.

Progress:

Take a sheet of plywood, plastic, or other easy-to-cut opaque material. Its dimensions should be approximately 300 by 300 millimeters, the thickness is not critical. Cut a straight slit in its middle about 100 mm long and about 4 mm wide.

Position the sheet vertically. Make a stand for it so that it does not need to be held in your hands, because you will have to hold two more objects in them, darken the room.

Turn on a continuous spectrum point light source. It can be, for example, a pocket flashlight based on an incandescent bulb. Position it about 500 millimeters from the gap.

On the opposite side of the slot, place a piece of plain paper at a 90 degree angle. Fasten it.

Take a regular CD (a dark one like RW won't work). Position it between the slit and the sheet of paper so that the spectrum is projected onto it.

While holding the flashlight and disk, ask an assistant to take a picture of the resulting rainbow.

Hold the flashlight and disk so that the spectrum does not shift. Please note that it is noticeably more sensitive to disc shift than to flashlight shift.

Then ask the assistant to take colored pencils or felt-tip pens. Have an assistant trace the spectrum with pencils or felt-tip pens in the colors that match those projected.

Remove the resulting sheet, then turn off the flashlight and disassemble the installation. Turn on the lights in the room. Compare the resulting photo and drawing with each other.

Answer the question why are the colors in any spectrum always in the same order?

Experience 5. Rainbow fountain.

Equipment and materials: tin can, scissors, light bulb, water.

Progress:

In a high tin can, at a height of 5 cm from the bottom, it is necessary to drill a round hole with a diameter of 5 - 6 mm. light bulb with a cartridge, carefully wrap it with cellophane paper and place it opposite the hole. You need to pour water into the jar. Opening a hole , we get a jet that will be illuminated from the inside. In a dark room, it glows brightly and looks very impressive.

2.2. Results of experimental work

Mom and dad and I did the experiments described in paragraph 2.1 at home. The results obtained during the experimental part of the work can be described as follows:

Experience 1. Rainbow in a basin.

Fill a glass cup with water. Then they lowered a mirror into the water and lit it with a flashlight. They moved the mirror, and found a position in which a rainbow formed on the walls of the room. When the water calmed down, the rainbow became more distinct.

Observations:

We got a kind of rainbow reflected on the mirror (Appendix 1). The beam of light reflected by the mirror at the exit from the water is refracted. The colors that make up White color, have different angles of refraction, so they fall at different points and become visible.

Experience 2. Rainbow on a white sheet.

Everything remained from experiment 1, only they additionally put a sheet of white paper in front of a cup of water, directed the light of a flashlight to a mirror, a rainbow will appear on a sheet of paper.

Observations:

We managed to catch a ray with a mirror that gave us such a rainbow ... (Appendix 2).

Experience 3. Rainbow in a box.

We took a large cardboard box. A vertical slot was cut in its side wall, and a blank CD was placed on the opposite wall of the box. A hole was cut in the side wall of the box for a tube to observe the spectrum.

Insert the tube into the hole. Aim a light source at the crack. We looked into the tube, and, turning it, found the spectrum.

We photographed the spectra obtained with a home spectroscope and compared them.

Observations:

By illuminating the disk with different light sources (a flashlight, an incandescent lamp), we obtained spectra of the same composition, which can be seen in the photographs (Appendix 3).

Experience 4. Studying the arrangement of colors in the rainbow.

From a sheet of plywood, we made a stand. A straight slit was cut in the middle of one side. Lay a sheet of white paper vertically. Darkened the room. A compact disc was placed between a slot and a piece of paper so that rays of light fell on it. A pocket flashlight illuminated the gap.

Observations:

A rainbow appears on a sheet of paper (Appendix 4), the colors in any spectrum are always arranged in the same order.

Experience 5. Rainbow fountain.

Dad drilled a round hole in a tall tin can. We poured water into the jar. An electric light bulb with a cartridge was carefully placed opposite the hole. A hole was opened in the dark room.

Observations:

We got a jet that is illuminated from the inside, it glows brightly. A finger was put on the path of the jet, and the water was sprayed in the form of a fountain, in which the ejected jets are illuminated from the inside (Appendix 5).

Conclusion

After completing this work, I was convinced how much amazing, instructive, useful for practice can be in the well-known phenomenon of light refraction.

During my research, I came up with the following conclusions:

To obtain a rainbow in the laboratory, there are many methods and techniques.

The experimental part describes several installations with which an artificial rainbow was obtained at home.

The results obtained in the study of the rainbow can be interesting and useful both for an outside observer and for schoolchildren.

In conclusion, it should be noted that the rainbow is very interesting phenomenon, the study of which requires great effort and is very informative, and practical value work is that the materials obtained can be used by teachers primary school when conducting lessons and classes to familiarize themselves with the outside world.

Bibliography

"The Great Encyclopedia of Cyril and Methodius".

Belkin I.K. What is a rainbow? - "Quantum" 1984, No. 12, S. 20.

Bulat V.L. Optical phenomena in nature. M.: Education, 1974, 143 p.

Geguzin Ya.E. "Who is making the rainbow?" - "Quantum" 1988, No. 6, S. 46.

Zvereva S.V. In the world of sunshine. - L .: Gidrometeoizdat, 1988.

Mayer V.V., Mayer R.V. "Artificial Rainbow" - "Quantum" 1988, No. 6, p.48.

Tarasov L.V. Physics in nature. - M.: Enlightenment, 1988.

http://www.allbest.ru

Annex 1.

Photos of the results of experience 1

Figure 1. Preparing equipment for work.

Picture 2. We install a mirror in a plate with water.

Figure 3 General form rainbows on the wall.

Figure 4. Enlarged rainbow reflection.

Appendix 2

Photos of the results of experience 2

Figure 5. Reflection of a rainbow on a sheet of paper.

Figure 6. View of a rainbow on a sheet of white paper.

Appendix 3

Photos of the results of experience 3

Figure 7. Preparing the spectroscope from the cardboard box.

Figure 8. Preparing the spectroscope from the cardboard box.

Figure 9. Illumination of the disk with a flashlight.

Figure 10. Watching the appearance of a rainbow in a box.

Figure 11. The sector of the rainbow, which we obtained when illuminated by a flashlight with LED lamps.

Figure 12. Rainbow sector, which we obtained when illuminated by a flashlight with LED lamps.

Figure 13. The sector of the rainbow, which we received when illuminated by an incandescent lamp.

Figure 14. The sector of the rainbow, which we received when illuminated by an incandescent lamp.

Appendix 4

Photos of the results of experience 4

Figure 15. Plywood layout.

Figure 16. A CD that will refract light.

Figure 17. Rainbow on a sheet of paper (A and B).

Appendix 5

Photos of the results of experience 5

Figure 18. Installation for obtaining a rainbow fountain.

Figure 19. Pour water into the installation to get a rainbow fountain.

Figure 20. Open the hole and get a rainbow jet.

Figure 21. Getting the rainbow fountain.

Ankudinova Valeria

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Ministry of General and Vocational Education

Sverdlovsk region

Municipal state educational institution

"Verkhnedubrovskaya secondary school"

Wonderful phenomenon of nature - rainbow-arc

abstract

Performer: Valeria Ankudinova, student of the 3rd grade,

Head: Malykh E.I., primary school teacher of the first quarter. categories

Upper Dubrovo, 2013

Introduction

Rainbow is one of the most beautiful natural phenomena. Once I heard a fairy tale, and it said that in the place where the rainbow ends, there are treasures. Many have tried to find them, but to no avail.

Among the brightest natural phenomena, the rainbow is one of the most beautiful.Which of the natural phenomena can be compared in beauty with a rainbow? Perhaps the aurora borealis, only not many people have seen it.A thunderstorm will pass, and a rainbow flashes in the sky. Sometimes you can see two rainbows at once. The second, as a rule, is much paler than the first, and the colors in it go in reverse order.She is so beautiful that she is sung in many songs, described in literature, legends are made about her. Many people, like me, look forward to the rain to see the rainbow.

Adults do not perceive the rainbow as children do. For children, a rainbow is magic, and for adults, it is memories of childhood and joy.

Then I decided to find out the whole history of the origin of the rainbow.

What is this colorful miracle of nature? How is a rainbow formed? Is it possible to observe this beauty at home? What other rainbows exist?

These questions intrigued me. And this topic became interesting to me because not many people know how a rainbow is formed. To answer all the questions that have arisen, I decided to conduct research work.

By investigating this riddle of nature, I will be able to give an exact answer to the questions I have posed.

Target my job: to find out the reason for the appearance of a rainbow.

Delivered by me tasks :

1. Find out who painted the rainbow.
2. Learn the history of the study of the rainbow.

Object of studyis a natural phenomenon rainbow.

Subject of study- the concept of "rainbow" as a natural phenomenon.

What is a rainbow?

There are several versions of where the word rainbow came from. The most common that the word "rainbow" comes from "raiduga", which is translated from Ukrainian language means "motley arc".

In order to find out the cause of the rainbow, I started by studying the literature. In explanatory dictionaries, the concepts of a rainbow are given:

• A rainbow is a multi-colored arc in the firmament of heaven, formed due to the refraction of sunlight in raindrops.
• Rainbow is atmospheric phenomenon observed during or after rain.

The rainbow is one of the most beautiful natural phenomena, and people have long thought about its nature. Even Aristotle, the ancient Greek philosopher, tried to explain the cause of the rainbow.

I learned that rainbows can be seen near waterfalls, fountains sprayed by a sprinkler. At fountains and waterfalls it happened to see two or more arcs. You can create a curtain of drops from a hand sprayer yourself and, standing with your back to the sun, see a rainbow created by your own hands. When watering the plants in the garden on a bright sunny day, you can also see a small rainbow in the spray of water.

How does a rainbow appear?

After a hot, stuffy day, clouds thickened and it began to rain. When it stopped, the setting sun shone over the horizon. And at that time, under the dark cloud leaving, like a giant arc, curved to the ground, a rainbow appeared: seven pure colors, imperceptibly passing one into another - red, orange, yellow, green, blue, indigo, violet.

Why was there such a miracle in the air? And the reason for this is sunlight, which seems to be white, but in fact consists of seven colors. When rays of sunlight pass through the air, we see them as white light. But a raindrop met on their way. A drop in shape is close to a prism - a geometric figure.

When a ray of sunlight passes through a glass prism or through a drop, its constituent rays are deflected at unequal angles. Red rays are deflected the least, and violet rays the most. The white beam breaks up into component beams, and a beautiful multi-colored bunny appears on the wall behind the prism, and a rainbow appears in the sky.

The outer edge of the curved band of the rainbow is usually red. It is followed to the inner edge by other colors of the rainbow spectrum, up to blue and violet.

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 reversed: purple is on the outside, and red is on the inside.

A rainbow appears only during a downpour, when it is raining and the sun is shining at the same time. It is necessary to be strictly between the sun (it should be behind) and the rain (it should be in front of you). Otherwise, you won't see the rainbow!

The sun sends out its rays, which, falling on the raindrops, create a spectrum. The sun, your eyes and the center of the rainbow should be in line.

If the sun is high in the sky, it is impossible to draw such a straight line. This is why rainbows can only be seen in the early morning or late afternoon. The morning rainbow means the sun is in the east and the rain is in the west. With an afternoon rainbow, the sun is in the west and the rain is in the east.

To remember the sequence of colors in the rainbow, people have come up with special simple phrases. In them, the first letters correspond to the first letters of the color names:

1. How once Zhak- z vonar broke a lantern with his head.
2. To the mouth about the whole, the zhirafu, the hare are blue with sewn sweatshirts.
3. Every hunter wants to know where the pheasant goes.

What are rainbows?

During my research, I learned that there are different kinds of rainbows on earth.

A rainbow comes with one or two arcs.Few people know, but there is also a night rainbow. At night, when the rain stops, a rainbow can also occur as a result of the action of the rays reflected by the moon. Undoubtedly, it is not as bright as during the day, but it can be seen remarkably. IN winter time a rainbow occurs very rarely, but in its brilliance and picturesqueness it differs from all the others.

Red…

The red rainbow appears in the sky only at sunset and is the last chord of the common rainbow. Sometimes it is extremely bright and remains visible even 5-10 minutes after sunset. At sunset, the rays travel a longer path through the air, and since the refractive index of water for longer wavelength (red) light is less than for short wavelength (violet), red light is less deflected by refraction. When the Sun dips below the horizon, the rainbow first loses the shortest - purple - waves. They dissipate immediately. Then the blue, light blue, green, yellow ones disappear ... The most persistent one remains - the red arc ..

White…

Why does the rainbow appear white to us? The point is the size of the droplets from which the sun's rays are reflected. A white rainbow appears in foggy weather. The dimensions of the fog particles are so small that the individual colored stripes, into which the sunbeam breaks up when refracted, diverge to the sides not as a wide multi-colored fan, but as a barely opened one. The colors seem to be superimposed on each other, and the eye no longer distinguishes colors, but sees only a colorless light arc - a white rainbow.

Lunar…

At night, when high in the dark, necessarily dark, sky hangs a full, necessarily full, moon and at the same time opposite the moon it's raining may be lucky enough to see the night rainbow! There are a lot of conditions for its appearance, so we rarely see the lunar rainbow. Rarely, but possible! And she, too, will appear white to us. It's actually quite colorful though.

The fact is that our vision is arranged in such a way that in low light the most sensitive receptors of the eye - “rods” - almost do not work, so the lunar rainbow looks whitish.

Fiery…

A fiery rainbow is one of the rarest atmospheric phenomena. It is formed due to the passage of light through light cirrus clouds and occurs only when the sun is very high in the sky ...

It turns out that the mysterious heavenly "fire" is born from ice! After all, cirrus clouds are located very high above the earth, where it is very cold at any time of the year, and therefore they consist of flat ice crystals!

Unfortunately, this is, to put it mildly, a coincidence - hexagonal crystals, cirrus clouds and high standing sun- doesn't happen often. That is why the fiery rainbow is a relatively rare and unique phenomenon.

"Smiley" in the skyan inverted rainbow (otherwise called a near-zenith) is a type of fiery rainbow and is even rarer. In addition to the conditions for the appearance of a fiery rainbow, for it to appear as a rainbow smiley in the sky, it is necessary that the center of its arc be at a zenith point located approximately 46 ° above the Sun. the near-zenith rainbow is very bright, with the colors of the spectrum reversed: purple at the top, red at the bottom.

Newton's study

I wonder if anyone in the history of mankind tried to know the nature of the rainbow?

I found the answer to this question on the Internet.

The first attempt to explain the rainbow was made in 1611 by Archbishop Antonio de Dominis. His explanation of the rainbow was contrary to the biblical one, so he was excommunicated and sentenced to death.

The scientific explanation of the rainbow was first given by René Descartes in 1637. Descartes explained the rainbow based onlaws refraction and reflection of sunlight in raindrops. But he did not yet know about the decomposition of white light into a spectrum upon refraction. Therefore, Descartes' rainbow was white.
30 years later, Isaac Newton explained how colored rays are refracted in raindrops. According to the figurative expression of the American scientist A. Fraser, who made a number of interesting studies of the rainbow in our time, “Descartes hung the rainbow in the right place in the sky, and Newton colored it with all the colors of the spectrum.”Although the multi-color spectrum of the rainbow is continuous, according to tradition, 7 colors are distinguished in it. 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 purple.

Despite being over 300 years old, the Descartes–Newtonian theory of the rainbow correctly explains the basic features of the rainbow, including the arrangement of the colors.

So, we found out that the rainbow is round. Plus, it's multi-layered. Passing through a drop, a white sunbeam turns 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 comes green, etc., the inner one is purple.

Legends of the peoples of the world

People have long thought about the nature of this beautiful phenomenon. Humanity has associated the rainbow with many beliefs and legends.

IN ancient Greek mythology, for example, a rainbow is a road between heaven and earth, along which a messenger walked between the world of the gods and the world of people, Irida.

In China, it was believed that the rainbow is a heavenly dragon, the union of Heaven and Earth.

In Slavic myths and legends, a rainbow was considered a magical heavenly bridge thrown from heaven to earth, a road along which angels descend from heaven to draw water from rivers. They pour this water into the clouds, and from there it falls like life-giving rain.

Superstitious people believed that the rainbow is a bad sign. They believed that the souls of the dead pass into the other world along the rainbow, and if a rainbow appeared, this meant someone's imminent death.

The rainbow also appears in many folk omens associated with weather forecasting. For example, a rainbow high and steep portends good weather, and low and flat - bad.

Conclusion

Having done this work, I became convinced that the rainbow is a well-known optical phenomenon in the atmosphere; observed when the sun illuminates the veil of falling rain and the observer is between the sun and the rain. The rainbow is observed not only on the veil of rain. On a smaller scale, it can be seen on drops of water near waterfalls, fountains and in the surf. At the same time, not only the Sun and the Moon, but also a searchlight can serve as a light source.

Interesting arrangement of colors in the rainbow. It is always constant. The red color of the main rainbow is located on its upper edge, purple - on the lower one. Between these extreme colors, other colors follow each other in the same sequence as in the solar spectrum. In principle, the rainbow never contains all the colors of the spectrum. Most often, blue, dark blue and saturated pure red colors are absent or weakly expressed in it. With the increase in the size of raindrops, the color bands of the rainbow narrow, and the colors themselves become more saturated.

At the same time, I learned how, thanks to Newton, age-old ideas about the origin of flowers were destroyed.

Literature

1. Ozhegov S.I. and Shvedova N.Yu. Dictionary Russian language. 4th edition., enlarged. - M .: LLC "A TEMP", 2008.

2. Travina I.V. 365 stories about planet Earth/Science-pop edition for children. - M.: CJSC "ROSMEN-PRESS", 2007.

3. Encyclopedia for the curious "Where, what and when?" CJSC Company "Makhaon" - M .: 2007.

Anna Lifanova
What is a rainbow? Abstract cognitive activity for older preschool children

Target. The development of the analytical and synthetic abilities of the child.

Tasks:

introduce children with the property of light to turn into rainbow spectrum;

Expand ideas about mixing colors that make up white.

Material and equipment: Presentation with reproductions of paintings by artists depicting rainbows, a liter bowl of water, a bottle of light nail polish.

Lesson progress:

caregiver: Listen guys. poem:

Rainbow

Rainbow hung in the spring sky,

Cheerfully from the sky looked at the earth.

Joyfully we smiled back:

- rainbow - rainbow, color - overexposure.

Rainbow hung in the sky for a short time,

From the sky to the earth for a short time looked:

Melted ...

What does she remember for everyone

Left?

red poppies,

yellow sand

Green lit up

There is a leaf on the branch.

beetle purple

Warms the sides

blue splashes

River to the banks.

orange sun

The forests are warmed

And at the starling

Blue eyes. V. Stepanov

caregiver: Guys, look at the reproductions of famous artists. What do you see in all these pictures?

Children: rainbow

caregiver: Does anyone know what such a rainbow and how does it appear?

Children answer that it appears after the rain, when the sun is shining.

caregiver: Rainbow- one of the most beautiful phenomena of nature.

Have you guys ever seen rainbow?

What does she look like?

The teacher listens to the answers children: On the rocker, on the arc, on the bridge, etc.

caregiver: Since ancient times, man has thought about the nature of origin rainbows and associated the appearance of a multi-colored arc in the sky with many beliefs and legends. Some thought that the rainbow is the heavenly bridge, from which gods or angels descended to earth, others said that this was the road between heaven and earth or from the gate to another other world.

In fact, rainbow- This is an atmospheric phenomenon that occurs when the Sun illuminates many water droplets during rain or fog, or after rain. When the sun's rays are refracted in water droplets during rain, a multi-colored arc appears in the sky.

And let's remember how many colors it has rainbow and what?

Children: 7 colors, list colors, remembering a famous rhyme: "Every hunter wants to know where his pheasant is sitting".

caregiver: Now we will try to create our own rainbow

Experience « rainbow film»

Put a bowl of water on the table so that direct rays of light do not fall on it. Hold a brush from a bottle of varnish over a bowl until a drop of varnish falls into the water. Watch the surface of the water. Move your head to look at the water from different angles. What did we see?

On a thin layer of varnish spilled over the water, one can see iridescent play. The varnish forms a thin film on the surface of the water. When light falls on the surface of this film, each of its rays is partially reflected from it. The other part of the beam reaches the bottom surface of the film and is also reflected from it. The reflections of the rays add up to each other, and we can see the overflows rainbow tones.

Physical education minute:

In the sky rainbow hanging in the air"draw" rainbow

The kids are amused. reach up and wave your hands

From it, as from a hill, put your hands down

Egorka, the rooster, are coming,

Cat, pig and me. bend the fingers on the hand

caregiver: Now we will play with paints. Let's mix colors to draw rainbow.

K - red

O - orange

W - yellow

G - green

G - blue

C - blue

F - purple

We only have 4 colors: red, yellow, blue, white.

How can we draw rainbow?

Children offer their own options for mixing colors.

caregiver: Let's check your answers. We have red, orange = red + yellow, yellow - yes, green = blue + yellow, blue = blue + white, blue yes, purple = blue + red.

I invite everyone to draw their own rainbow, just do not confuse the arrangement of flowers.

And in the end classes, we will play with soap bubbles again. After releasing bubbles, carefully look at them. Each bubble has Iris, which also includes all colors.