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Introduction 3
Chapter 1. Literary analysis on research topic 5
1.1. The historical aspect of studying topic 5
1.2. Basic concepts of the problem under study 6
1.3. Characteristics of types of rainbow 9
Chapter 2. Experimental 11
2.1. Experimental technique 11
2.2. Experimental Results 14
Conclusion 17
References 18
Appendix 1.19
Appendix 2.21
Appendix 3.22
Appendix 4.26
Appendix 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 magical properties to her. Everyone knows that a rainbow can have magical properties only in fairy tales, but in reality a rainbow is optical phenomenonassociated with the refraction of light rays on numerous drops of rain. However, not everyone knows exactly how a rainbow is formed. When and how can you see it? Can you experimentally investigate a rainbow? How to get an artificial rainbow? Answers to these and many other questions are given in this work.
Object of study: a natural phenomenon - a rainbow.
Subject of study: ways to get a rainbow.
I put forward the next hypothesis: using different laboratory settings, you can get an artificial rainbow and explore it physical properties in the laboratory.
Purpose of my research: reveal the physical properties of the rainbow and experimentally test methods for its production in laboratory conditions.
I achieved my goal by deciding tasks:
collect information about the methods of obtaining, properties and types of the rainbow;
to design laboratory installations for obtaining a rainbow and to 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 parents, read in a book, find it on the Internet);
pick up experimental work to get an artificial rainbow;
design laboratory facilities for producing an artificial rainbow;
to make an experiment;
compare the theoretical and practical results for obtaining an artificial rainbow;
formalize 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
- The historical aspect of studying the topic
In Russian chronicles, the rainbow is called the "paradise arc" or abbreviated "raiduga". IN Ancient Greece the rainbow was personified by the goddess Irida (Irida means rainbow). According to the ancient Greeks, the rainbow connects heaven and earth, and Iris was the mediator between gods and people. The rainbow is a physical phenomenon. 8
A rainbow is always associated with rain. It can appear before the rain, and during the rain, and after it, depending on how the cloud that gives rainfall moves.
The first attempt to explain the rainbow as a natural phenomenon of nature was made in 1611 by Archbishop Antonio Dominis. His explanation of the rainbow was contrary to the biblical, so he was excommunicated and sentenced to death. 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 René 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 was not yet discovered - the decomposition of white light into a spectrum during refraction. Therefore, Descartes' rainbow was white.
After 30 years, Isaac Newton, who discovered the dispersion of white light by refraction, supplemented Descartes's theory by explaining how colored rays are refracted in raindrops. 3
Despite the fact that Descartes - Newton's rainbow theory 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.
- Basic concepts of the problem under study
A common rainbow is a colored arc with an angular radius of 42 °, visible against a background of heavy rain curtains or rain stripes that often do not reach the Earth's surface. The rainbow is visible in the side of the firmament opposite to the Sun, and always when the Sun is not covered by clouds. The center of the rainbow is the 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 violet. 2
The fact is that a more or less spherical drop, illuminated by a parallel beam 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 the whole circle.
As a result of passing through the drop and refraction in it, a cylinder of white rays is transformed into a series of colored funnels inserted into one another. The outer funnel is red, orange and yellow are inserted into it, then goes green, and so on, ending with the inner purple. 4
The size and shape of drops and their effect on the appearance of the rainbow
Rainbow appearance - the width of the arcs, the location and brightness of the color tones, the position of additional arcs are very dependent on the size of the raindrops. By the appearance of the rainbow, you can roughly estimate the size of the raindrops that formed this rainbow. The larger the raindrops, the narrower and brighter the rainbow is. Particularly characteristic of large drops is the presence of a rich red color in the main rainbow. The smaller the drops, the wider and faded the rainbow becomes, with an orange or yellow edge. The additional arcs are further apart from each other and from the main rainbows. 8
The type of rainbow depends on the shape of the drops. When falling in the air, large droplets flatten, lose their sphericity. The vertical section of such droplets approaches an ellipse.
Can you see the whole circle of the rainbow? From the surface of the Earth, you can see a rainbow at best in the form of half a circle when the Sun is on the horizon. When the sun rises, the rainbow goes under 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 type of 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 rain drops. Here are the main characteristics appearance rainbows for drops of different radii. 5
Droplet 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. Purple and green seem especially bright. There are many additional arcs (up to five), in which purple-pink tones alternate with green ones. Additional arcs are directly adjacent to the main rainbows.
The radius of the drops is 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.
Droplet 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 more and more yellow. Gaps appeared between them and between the main rainbow and the first additional one.
Droplet radius 0.04—0.05 mm.The rainbow became noticeably wider and paler. Its outer edge is pale yellow. The brightest color is purple. The first additional arc is separated from the main rainbow by a rather wide gap; its color is whitish, slightly greenish and whitish-purple.
The radius of the drops is 0.03 mm.The main rainbow is even wider with a very faintly colored slightly yellowish edge and contains separate white stripes.
The droplet radius is 0.025 mm or less.The rainbow turned completely white. It is about twice as wide as a regular rainbow and looks like a shiny white stripe. Inside it there may be additional colored arcs, first pale blue or green, then whitish red. 1
Thus, by looking at the rainbow, you can roughly estimate the size of the raindrops that formed this rainbow. In general, the larger the raindrops, the narrower and brighter the rainbow is, especially for large drops is the presence of a rich red color 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 becomes with an orange or yellow edge. The additional arcs are further apart from each other and from the main rainbows.
The type of rainbow depends on the shape of the drops. When falling in the air, large droplets flatten, lose their sphericity. The vertical section of such droplets 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, for example 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
- Characteristics of rainbow species
Are there rainbows without rain or without rain streaks? There are - in the laboratory. Artificial rainbows were created by refraction of light in a single suspended droplet of distilled water, water with syrup, or clear oil. The droplet sizes varied from 1.5 to 4.5 mm. Heavy droplets stretched out under the action of gravity, and their cross section was an ellipse. When the droplet was illuminated by a helium-neon laser beam, 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 get even the fifth and sixth rainbows. These rainbows, like the first and second, were again on the side 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 ray. 8
Misty rainbow
White rainbows are found in nature. They appear when illuminated by the sun's rays of a weak 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 shiny white arc with a barely noticeable yellowish edge, sometimes colored additional arcs are observed: a very weak blue or green arc, and then whitish-red.
A similar white rainbow can be seen when a spotlight behind you illuminates intense haze or faint fog in front of you. Even a street lamp can create, albeit very faint, white rainbows visible against the dark background of the night sky. 6
Moon rainbows
Lunar rainbows can appear similarly to solar ones. They are weaker and appear during the full moon. Lunar rainbows are more rare than solar ones. For their occurrence, a combination of two conditions is necessary: full moon, not covered by clouds, and heavy rainfall or stripes of its fall (not reaching the Earth).
Moonbeams are not iridescent and appear as light, completely white arcs. The lack of red color in lunar rainbows even with large raindrops is explained by the low level of illumination at night, at which the eye's sensitivity to red rays is completely lost. The rest of the colored rays of the rainbow also lose their color tone to a large extent due to the uncolored night vision of a person. 8
Chapter 2. Experimental 2.1. Experimental technique
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.
Working process:
On a sunny day, fill a large glass container with water. Then put the mirror in the water. Move this mirror and find such a position in which a rainbow forms on the walls of the room. You can fix the position of the mirror, let the water calm down to make the rainbow more distinct, and then draw or photograph the rainbow as you saw it.
Equipment and materials: glass container; water; mirror; white sheet of paper; Lantern.
Working process:
On a sunny day, fill a large glass container with water. Then put the mirror in the water. Move this mirror and find such a position in which a rainbow forms on the walls of the room. You can fix the position of the mirror and let the water calm down to make the rainbow more distinct. Additionally, put a sheet of white paper in front of a basin with water and a mirror, direct the light of the flashlight to the part of the mirror submerged in water, a rainbow will appear on the sheet of paper. Then draw or photograph the rainbow as you saw it.
Experience 3. Rainbow in a box.
Equipment and materials: cardboard box; stationery knife; CD-R compact disc; plastic tube; glue; Lantern; candle; Fluorescent Lamp.
Working process:
Take a large cardboard box. In its side wall, cut a vertical slit several 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 side of the box.
Now cut a hole in the side wall of the box for the tube to observe the spectrum. Although the tube is circular, the hole must be oval so that it can be rotated horizontally.
Insert the tube into the hole. Aim the slit towards the light source. Look into the tube, and by turning it, find the spectrum and examine it.
Try observing the spectra of various light sources with a spectroscope: the sun, incandescent lamps, fluorescent lamps, candles, 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 lantern, a sheet of white paper, a CD, pencils, a camera.
Working process:
Take a sheet of plywood, plastic, or other easy-to-handle, 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 millimeters wide.
Place the sheet vertically. Make a stand for it so that you do not need to hold it 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. This can be, for example, a pocket torch based on an incandescent light bulb. Place it about 500 millimeters from the gap.
On the opposite side of the slot, place a sheet of plain paper at a 90-degree angle. Secure it.
Take a regular CD (a dark one like RW will not work). Place it between the slit and the sheet of paper so that the spectrum is projected onto it.
Holding the flashlight and disc, ask your assistant to photograph the resulting rainbow.
Hold the flashlight and dial so that the spectrum does not shift. Note that it is noticeably more sensitive to disk shift than flashlight shift.
Then ask a helper to pick up colored pencils or a felt-tip pen. Have an assistant trace the spectrum with pencils or felt-tip pens that match the projected colors.
Remove the resulting sheet, then turn off the flashlight and disassemble the installation. Turn on the lights in the room. Compare the resulting photograph and drawing with each other.
Answer the question, why are colors in any spectrum always in the same order?
Experience 5. Rainbow fountain.
Equipment and materials: tin can, scissors, light bulb, water.
Working process:
In a tall tin can at a height of 5 cm from the bottom, drill a round hole with a diameter of 5 - 6 mm. The light bulb with the socket must be carefully wrapped in cellophane paper and placed opposite the hole. You need to pour water into the jar. Opening the hole , we get a stream that will be illuminated from the inside. In a dark room, it glows brightly and looks very impressive.
2.2. Experimental results
My mom and dad and I performed 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 such 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 rainbow view reflected on a 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 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 placed a sheet of white paper in front of a cup of water, directed the light of a flashlight to a mirror, a rainbow would 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.
We inserted the tube into the hole. Direct the light source to the slit. We looked into the tube and, turning it, found the spectrum.
We photographed the spectra taken with a home spectroscope and compared them.
Observations:
By illuminating the disc with different light sources (flashlight, incandescent lamp), we obtained spectra of the same composition, which can be seen in the photographs (Appendix 3).
Experience 4. Study of the arrangement of colors in the rainbow.
We made a stand from a sheet of plywood. A straight slit was cut in the middle of one side. Place a sheet of white paper vertically. The room was darkened. The CD was placed between the slot and the sheet of paper so that the rays of light fell on it. A pocket flashlight illuminated the gap.
Observations:
A rainbow appears on a sheet of paper (Appendix 4), 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. The light bulb with the socket was neatly placed opposite the hole. A hole was opened in a dark room.
Observations:
We received a stream that is illuminated from the inside, it shines brightly. A finger was placed on the path of the stream, and the water was sprayed in the form of a fountain, in which the ejected streams are illuminated from the inside (Appendix 5).
Conclusion
Having completed this work, I was convinced how much surprising, instructive, and useful for practice can be in the well-known phenomenon of light refraction.
In the course of my research, I formulated the following conclusions:
There are many methods and techniques for producing rainbows in the laboratory.
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 a very interesting phenomenon, the study of which requires a lot of effort and is very informative, and practical value work is that the materials received can be used by teachers primary grades when conducting lessons and classes to familiarize yourself with the outside world.
Bibliography
"Great Encyclopedia of Cyril and Methodius".
Belkin I.K. What is a rainbow? - "Quant" 1984, no. 12, p. 20.
Bulat V.L. Optical phenomena in nature. M .: Education, 1974, 143 p.
Geguzin Ya.E. "Who Makes the Rainbow?" - "Quant" 1988, No. 6, P. 46.
S.V. Zvereva In a world of sunshine. - L .: Gidrometeoizdat, 1988.
Mayer V.V., Mayer R.V. "Artificial rainbow" - "Quant" 1988, no. 6, p. 48.
L.V. Tarasov Physics in nature. - M .: Education, 1988.
http://www.allbest.ru
Photos of the results of experiment 1
Figure 1. Equipment preparation for work.
Figure 2. Installing the mirror in a bowl of water.
Figure 3. General view of the rainbow on the wall.
Figure 4. Magnified reflection of the rainbow.
Appendix 2.
Photos of the results of experiment 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 experiment 3
Figure 7. Preparing the spectroscope from the cardboard box.
Figure 8. Preparing the spectroscope from the cardboard box.
Figure 9. Lighting the disc with a flashlight.
Figure 10. Watching the appearance of the rainbow in the box.
Figure 11. The sector of the rainbow, which we received when illuminated by a flashlight with LED lamps.
Figure 12. The sector of the rainbow, which we received when illuminated by a flashlight with LED lamps.
Figure 13. Sector of the rainbow, which we received when illuminated by an incandescent lamp.
Figure 14. The sector of the rainbow, which we received under the illumination of an incandescent lamp.
Appendix 4.
Photos of the results of experiment 4
Figure 15. Plywood layout.
Figure 16. A compact disk with which the light will be refracted.
Figure 17. Rainbow on a piece of paper (A and B).
Appendix 5.
Photos of the results of experiment 5
Figure 18. Installation for a rainbow fountain.
Figure 19. Pouring water into the installation for a rainbow fountain.
Figure 20. Open the hole and get a rainbow jet.
Figure 21. Getting a rainbow fountain.
The general physical picture of the rainbow has already been clearly described. By Mark Antony de Dominis (1611). On the basis of experimental observations, he came to the conclusion that a rainbow is obtained as a result of reflection from the inner surface of a raindrop and double refraction - upon entering and exiting the drop.
Rene Descartes gave a more complete explanation of the rainbow in his work "Meteora" in the chapter "On the rainbow" (1635)
Isaac Newton in the treatise "Optics or Treatise on Reflections, Refractions, Bending and Colors of Light" he supplemented the theory of the rainbow in relation to the colors of the rainbow and explained the mechanism of formation of a secondary rainbow.
The full theory of the rainbow, taking into account the diffraction of light, which depends on the ratio of the wavelength of light to the size of the drop, was built only in the 19th century J. B. Erie (1836) and J.M. Pernter (1897).
Newton called the system of colors of the disintegrated sunbeam spectrum - from lat. spectrum - view, vision, ghost.
In the rainbow, Newton singled out 7 colors.
The multicolor spectrum of the rainbow is continuous!)
Why the colors of the rainbow are in strict sequence?
Each colored ray has its own bend angle. The violet, which occupies the lowest position in the spectrum, has the smallest angle.
Each of us sees our own "personal" rainbow.
When you look at a rainbow, you see light refracted from some raindrops, and the person standing next to you looks at the same rainbow and sees the light reflected from other raindrops.
Center of the circle described by the rainbow, lies on a straight line passing through the observer and the Sun, and the Sun is always behind the back of the observer.
What is the radius of the rainbow?
A rainbow is an optical effect produced by the refraction of sunlight in droplets of atmospheric moisture.
These drops can be at different distances from us. It is estimated that the height of the rainbow is about 0.9 distance from the observer's eyes. Since we see the rainbow as a semicircle, this value can be considered the radius of an imaginary circle into which the rainbow could be closed.
Does a rainbow have a beginning and an end?
In ideal conditions, in an airplane flight or from a high mountain, you can see the rainbow as a closed curve that surrounds a point diametrically opposite the Sun.
When the sun rises higher 42 degrees above the horizon, the rainbow is not visible from the surface of the Earth.
Brightness of the rainbow depends on the amount of raindrops. If they are large (1-2 mm in diameter), the rainbow is very bright.
Double Rainbow
due to the fact that the sun's rays are twice reflected in the drops above the drops that form a normal rainbow. In this case, the upper rainbow is always less bright than the main one, and the colors in it are arranged in reverse order.
Less common is a triple and even a rainbow of four arcs!
In this case, additional rainbows are located only above the central part of the main rainbows and disappear when the latter move to a vertical position.
The distance between two rainbows is called alexander's dark streak... It is named after the ancient Greek philosopher Alexander of Aphrodisia, who first described this phenomenon in 200. AD
Night rainbow - Moonlight rainbow
The lunar rainbow is a rare phenomenon in the refraction of moonlight. We see this rainbow as white, although all colors are present in it.
Fiery rainbow - one of the varieties of "halo" - an optical effect in the form of a luminous ring around the sun, which mainly appears in the area of \u200b\u200bcirrus clouds: small ice floes reflect the incident light and "ignite" the clouds, painting them in different colors.
The rainbow is one of the few natural phenomena that humans have learned to reproduce.
Artificial rainbows can be seen next to waterfalls and fountains. They appear against the background of tiny droplets sprayed by the installation.
Calculations using the formulas of the diffraction theory, performed for drops of different
size, showed that the whole type of rainbow - the width of the arcs, the presence, location and
brightness of individual color tones, the position of additional arcs is very strong
depend on the size of the raindrops. Here are the main characteristics of the external
rainbow type for drops of different radii.
Droplet 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.
Purple and green seem especially bright. There are many additional arcs (up to
five), they alternate purple-pink tones with green. Additional arcs
directly adjacent to major rainbows.
Droplet radius 0.25 mm... The red tap of the rainbow has become weaker. Other colors
are still visible. Several purple-pink additional arcs are replaced
green.
Droplet 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 more and more yellow. Between them and between the main
rainbow and the first additional gaps appeared.
Droplet radius 0.04-0.05 mm... The rainbow is noticeably wider and paler, Outside
its edge is pale yellow. The brightest is purple. The first
the additional arc is separated from the main rainbow by a rather 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 weak
painted with a slightly yellowish edge, contains separate white stripes.
Droplet radius 0.025 mm or less... The rainbow turned completely white. She is about
twice as wide as a regular rainbow and looks like a shiny white stripe. Inside her
there may be additional colored arcs, initially pale blue or green,
then whitish red.
Thus, by the appearance of the rainbow, you can roughly estimate the size of rain drops,
that formed this rainbow. In general, the larger the raindrops, the rainbow
turns out to be narrower and brighter, especially characteristic of large drops is
the presence of a rich red in the main rainbow. Numerous
additional arcs also have bright colors and directly, without
gaps adjoin the main rainbows. The smaller the drops, the rainbow
becomes wider and faded with an orange or yellow edge.
The type of rainbow depends on the shape of the drops. Large droplets falling in the air
flatten, lose their sphericity. The vertical section of such drops
approaches the ellipse. Calculations have shown that the minimum deviation of red
rays 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 more
large droplets, e.g. with a radius of 1.0 mm, minimal deviation of 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 droplet flattening, the smaller the radius
the rainbow they form.
The "secret" of additional arcs has been solved!
A. Fraser, considering at the same time the influence of the size and shape of drops on the species
rainbow, managed to reveal the "secret" of the appearance of additional arcs. As soon as
it was said that a decrease in the size of the prevailing droplets and a flattening of large
act in opposite directions. What will overpower? When and what
will the influence prevail?
A clear illustration of the interaction of both factors and their joint influence
the kind of rainbow are rice. 3 a and bcompiled by A. Fraser,
based on calculations: These figures show the intensity distribution
light in the main rainbow and additional arcs depending on the size of the drops.
A complex undulating surface in the foreground (Fig. 3 a)
composed of many individual curves. Each curve gives a distribution
and the intensity of light in a rainbow from one drop. Every fifth curve is drawn
thicker, the numbers on the right indicate the radius of the drop corresponding to the curve in
millimeters. All curves start from the left with very low intensity (outside
rainbows), then rapidly rise to a maximum between 138 ° and 139 ° (the first
rainbow). The next ridge to the right is the first additional arc, followed by the second
additional arc, etc. The distance between the arcs, as can be seen from the figure,
decreases rapidly with increasing droplet radius. This is the action of the first factor.
The rainbow becomes narrower as the droplets increase.
The upper S curve is the sum of the contributions of all droplet sizes.
It characterizes the distribution of light intensity in the final rainbow,
which we see.
137 138 139 140 141 142
Angular distance from the Sun
137 138 139 140 141 142
Angular distance from the Sun
Figure: 3. The distribution of light intensity in the main rainbow and additional
arcs depending on the droplet size.
a - excluding droplet flattening; b - taking into account the flattening of drops. S -
summary curve.
Figure 3 b the same curves are shown, but now the effect of flattening is taken into account
drops, the stronger the larger the drops. Individual curves for large
flattened drops are displaced towards large minimum angles of deviation from
The Sun (or, equivalently, in the direction of decreasing the radii of the rainbows), and as a result
the entire undulating surface turned out to be curved to the right (individual
the highs went to the right). This led to the fact that on the resulting total
curve appeared, in addition to the main rainbow, additional arcs, on the corner
distances from the Sun: the first -140.5 °, the second -141.3 °, the third - 142.4 °,
fourth-142.5 °.
Additional arcs are visible only near the top of the main rainbow, as they
formed only by vertical or close to them rays passing through
elliptical sections of drops.
It is shown by calculations, but this can also be traced in Fig. 3 b, what
additional arcs are created mainly by droplets ranging in size from 0.2 to 0.3 mm.
Larger and smaller drops produce maxima that overlap each other.
friend and too far from the main rainbow (they go to the right). Rainbow
drops with a diameter of 0.2-0.3 mm are in an advantageous position, since
their highs have not shifted anywhere. Thus, we can conclude that
additional arcs are visible if they are present in a heavy rain,
the amount of droplets with a radius of 0.25 mm and few larger droplets that lubricate
picture. Therefore, additional arcs are more often visible and the most colorful are not very
intense summer rain showers. They also appear against the background of a veil of
the smallest drops formed when splashing water in irrigation
installations.
Can you see the whole circle of the rainbow? From the surface of the Earth we can observe
a rainbow at best in the form of half a circle when the Sun is at
horizon. When the Sun rises, the rainbow goes under the horizon. The first rainbow is possible
to see at the heights of the Sun more than 42 °, and the second - more than 50 °. From the plane, and also
better from a helicopter (more view) you can see a rainbow in the form of a whole circle!
The description of such a circular rainbow (it and a rainbow, i.e. an arc, is already inconvenient
call it!) was published in the magazine "Nature."
flying in the region of Novosibirsk at an altitude of 1000 m.
Rainbow light polarization... Rainbow light is characterized by an unusually high
degree of polarization. In the first rainbow, it reaches 90%, in the second, about 80%. IN
this is easy to see if you look at the rainbow through a polarizing prism
Nicolas. At small angles of rotation of the prism, the rainbow disappears completely.
A rainbow without rain?
Are there rainbows without rain or without rain streaks? It turns out that there are -
in the laboratory. Artificial rainbows were created by refraction
light in one suspended droplet of distilled water, water with syrup, or
clear oil. The droplet sizes varied from 1.5 to 4.5 mm. Heavy drops
stretched under the action of gravity, and their cross section in the vertical
the plane was an ellipse. When the droplet is illuminated by a beam of helium
neon laser (with a wavelength of 0.6328 μm) appeared not only the first and
the second rainbow, but also the unusually bright third and fourth, centered around
a light source (in this case, a laser). Sometimes I managed to get even
fifth and sixth rainbows. These rainbows, like the first and second, sheaves were off to the side,
opposite to the source.
So, one drop has created so many rainbows! True, these rainbows were not
rainbow colored. They were all monochromatic, red, since they were not formed by white
a light source, but a monochromatic red beam.
Misty rainbow
In nature, there are white rainbows, which were mentioned above. They appear
when illuminated by the sun's rays of a weak fog, consisting of droplets
radius of 0.025 mm or less. They are called foggy rainbows. Besides the main
rainbows in the form of a shiny white arc with a barely noticeable yellowish edge
sometimes colored additional arcs are observed: very weak blue or
green arc and then whitish red.
A similar white rainbow can be seen when the spotlight
located behind you, illuminates 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.
Moon rainbows
Lunar rainbows can appear similarly to solar ones. They are weaker and
appear on a full moon. Lunar rainbows are more rare than
sunny. For their occurrence, a combination of two conditions is necessary: \u200b\u200bcomplete
Moon not covered by clouds and heavy rainfall or streaks
(not reaching the Earth). Heavy rains due to daytime convective
air movements, much less often fall out at night.
Lunar rainbows can be observed anywhere in the world where they come true
listed two conditions.
Daytime, sunny rainbows, even formed by the smallest drops of rain
or fog, rather whitish, light, and yet their outer edge at least
weakly, but colored orange or yellow... The rainbows formed by the moon
rays, do not justify their name at all, since they are not rainbow and
appear as light, completely white arcs.
The lack of red in lunar rainbows even with large rainfall drops
rain is due to the low level of lighting at night, in which completely
the sensitivity of the eye to red rays is lost. Other colored
rainbow rays also lose their hue to a large extent due to
achromatic (uncolored) night vision of a person.
Ministry of General and vocational education Russian Federation
A rainbow will make anyone smile! Especially large, stretching over the entire sky. Or a small one, nestled in a table fountain - it's so own, tame. What determines the size of the rainbow, and what is it all about? Read the tooltips on the diagram to figure it out.
1. A rainbow is an optical illusion. It occurs when water droplets (rain, fog, or spray from a waterfall) are illuminated by the sun. There are also lunar rainbows (one of these in the photo), they can be observed at night.
2. Falling into a drop, light is twice refracted at the boundary between air and water and is reflected from the “back” wall of the drop, returning at an angle of about 42 degrees to the light. The refractive index of light with different wavelengths is slightly different, so rays of different colors come out of the droplet at different angles. So white light turns into a rainbow.
3. The illusion of a rainbow is created by those drops that appear at the intersection of the sun's rays and the line of sight of the observer. All rainbows in the world have the same angular size - 42 degrees.
4. The linear radius of the rainbow depends on the distance between the observer and the water droplets. For example, a rainbow that appears 5 meters away from a person will have a radius of about 4.5 meters (5 meters times the tangent of 42 °).
5. The center of the rainbow is at the antisolar point - on the line connecting the observer and the sun. The plane of the rainbow is perpendicular to this line. The anti-sun point is imaginary and may be underground. By the way, on a clear day, a luminary is capable of creating not only illusory, but also quite tangible effects, for example.
People have asked this question for a long time. In some African myths, a rainbow is a snake that covers 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 colored strip?
The shape of the rainbow is determined by the shape of the water droplets in which sunlight is refracted. And the water droplets are more or less spherical (round. Passing through the drop and refracting in it, the beam of white sun rays is transformed into a series of colored funnels inserted one into the other, facing the observer. The outer funnel is red, orange, yellow is inserted into it, then goes green, and so on, ending with the inner violet, so 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 only one colored ray falls into the rainbow from a single drop. The eye of the observer is a common point at which colored rays from many drops intersect. For example, all red rays coming out of different drops, but at the same angle and falling into the eye of the observer, form a red arc of the rainbow. Also, all orange and other colored rays form arcs. Therefore, the rainbow is round.
We are used to seeing a rainbow as an arc. In fact, this arc is only a part of the multi-colored circle. This natural phenomenon as a whole can be observed only at high altitudes, for example, from an airplane.
When the last raindrops fall on the ground, and a rainbow appears in the sky, you, looking at it, wonder: why is this happening? Where does a beautiful arc of multi-colored stripes come from in the sky? The science of physics will help to answer this question, which has more than once given you answers to many difficult questions.
The rainbow is an extraordinary natural phenomenon. And although we see her quite often, every time we rejoice at her appearance and beauty. The rainbow appears as soon as the cloud begins to leave, and the sun takes its place in the sky. It turns out that for some time the rain is visible to people as if "from the outside". The rays of the sun illuminate the rain cloud and, passing through the raindrops, change their color. The fact is that the sun's rays are not at all white and the same, as it seems to us. They all have different lengths, and each length has its own "color". That is why the rainbow seems so colorful to us.
But the color of the rainbow is bright, and it is barely noticeable. And it depends on the size of the raindrops. If the drops are large, the colors of the rainbow will be bright. If small - the celestial arc will be poorly visible. In the past, people could not explain the appearance of the rainbow. And it was difficult to find a person who would remain indifferent to her. Therefore, there are so many legends and beliefs associated with the rainbow. The ancient Slavs, looking at the rainbow, predicted the weather. If the rainbow was low and wide, the people expected bad weather. And high and narrow - promised good weather. 
In England, it is considered a good omen to see a rainbow and make a wish right away. And in Ireland even today they believe that in the place where the rainbow bumps into the ground, there is a treasure of gold. You, of course, are a fairly reasonable person, and do not believe in treasures of gold. And you understand that you can't get to where the rainbow touches the ground.
Are you wondering why we see only part of the rainbow? Let's talk about it. You've probably already noticed that you can't watch the sun and the rainbow at the same time. After all, a rainbow is a reflection of the sun's rays. Only part of the celestial arc is visible from the ground. But the higher a person climbs, for example, a mountain, the more the rainbow will look like a circle. And from the window of an airplane you will someday be able to see a round rainbow!
Why is the rainbow semicircular? People have asked this question for a long time. In some African myths, a rainbow is a snake that encircles the Earth in a ring. But now we know that the rainbow is 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 colored strip?
Two people standing next to each other see their own rainbow! Because at every moment the rainbow is formed by the refraction of the sun's rays in new and new drops. Raindrops are falling. The place of the falling drop is taken by another and manages to send its colored rays into the rainbow, the next one is behind it, and so on.
The type of 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 is. Large drops are characterized by a deep red color 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 becomes with an orange or yellow edge. The additional arcs are further apart from each other and from the main rainbows. Thus, by looking at the rainbow, you can roughly estimate the size of the raindrops that formed this rainbow.
The type of rainbow depends on the shape of the drops. When falling in the air, large droplets flatten, lose their sphericity. The stronger the flattening of the drops, the smaller the radius of the rainbow they form.
Heavenly rainbow is a beautiful and at the same time complex physical phenomenon that can be observed after rain or during fog, if the sun is shining. Many ancient beliefs and myths are associated with the rainbow different nations, and in Russia in the old days the weather was predicted from it. A narrow and high rainbow foreshadowed good weather, and a wide and low rainbow foreshadowed bad weather.
A rainbow is a meteorological phenomenon that occurs in the sky. It is a huge arc made of different colors. High moisture content in the air, which usually occurs after rain or fog, contributes to the formation of a rainbow. The multi-colored arc appears due to the refraction of sunlight in water droplets, which are contained in the atmosphere as vapor. Drops refract light in different ways, depending on the wavelength of the light. For example, red has the longest waves, so this color crowns the color spectrum of the rainbow, it belongs to the widest arc. Then the red color along the spectrum smoothly turns into orange, then into yellow, etc. The weakest in resistance to deflection in refraction in water is violet, its waves are the shortest, so the observer sees that this color belongs to the shortest arc of the rainbow - the inner ... The method of decomposing white sunlight into a color spectrum is called dispersion. In dispersion, the refractive index of light depends on the wavelength of the light wave. In optics, the phenomenon of a rainbow is called "caustics." A caustic is a light curved line of various shapes, in this case a semicircle or arc. The multi-colored rays that make up the rainbow run parallel to each other, without converging, so you can observe the color transition inherent in it throughout the rainbow. From childhood, everyone knows rhymes and sayings that help to remember the colors of the rainbow. For example, every student knows the saying “every hunter wants to know where the pheasant is sitting”. However, in reality, the color spectrum of the rainbow does not consist of seven colors, there are many more. Primary colors pass into each other through a large number of shades and intermediate colors. It should be added that a person can observe the phenomenon of a rainbow only in the course of sunlight. It is impossible to see the rainbow and the sun at the same time, the sun always remains behind. Moreover, the higher the observer is (on a hill or in an airplane), the more the visible shape of the rainbow approaches the circle.
Why is the rainbow round and the dome of the sky. WHY DOES THE RAINBOW HAVE AN ARC SHAPE?
Why is the rainbow semicircular? People have asked this question for a long time. In some African myths, a rainbow is a snake that encircles the Earth in a ring. But now we know that the 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 colored strip?
The shape of the rainbow is determined by the shape of the water droplets in which sunlight is refracted. And the water droplets are more or less spherical (round). Passing through the drop and being refracted in it, a beam of white sun rays is transformed into a series of colored funnels inserted one into the other, facing the observer. The outer funnel is red, orange and yellow are inserted into it, then the green one goes, and so on, ending with the inner purple. Thus, every single 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 a single drop, only one colored ray falls into the rainbow. The eye of the observer is a common point at which colored rays from many drops intersect. For example, all red rays that came out from different drops, but at the same angle and hit the eye of the observer, form a red arc of the rainbow. All orange and other colored rays also form an arc. Therefore, the rainbow is round.
Two people standing next to each other see their own rainbow! Because at every moment the rainbow is formed by the refraction of the sun's rays in new and new drops. Raindrops are falling. The place of the falling drop is taken by another and manages to send its colored rays into the rainbow, the next one is behind it, and so on.
The type of 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 is. Large drops are characterized by a deep red color 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 becomes with an orange or yellow edge. The additional arcs are further apart from each other and from the main rainbows. Thus, by looking at the rainbow, you can roughly estimate the size of the raindrops that formed this rainbow.
The type of rainbow depends on the shape of the drops. When falling in the air, large droplets flatten, lose their sphericity. The stronger the flattening of the drops, the smaller the radius of the rainbow they form.
We are used to seeing a rainbow as an arc. In fact, this arc is only a part of a multi-colored circle. This natural phenomenon as a whole can be observed only 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:
A rainbow is an atmospheric phenomenon. It appears in the sky before or after rain, and can be seen near a waterfall or above the spray at a fountain. It looks different - it can be an arc, sometimes in the form of a circle or splashes. For a rainbow to appear after rain, sunlight is needed.
Imagine that a rainbow is one ray of sunshine. Usually the sun's rays are invisible, as they are scattered by the air. Daylight sunlight is often referred to as white. In fact, the sensation of white light is caused by mixing colors such as red, orange, yellow, green, cyan, blue, and purple. This combination of colors is called the solar spectrum, and their combination gives white.
Green foliage, blue sky, the bright colors of nature are all the refraction of the sun's rays, which, passing through a thin layer of the atmosphere, reflect the constituent parts of the white color.
Isaac Newton introduced the concept of the spectral composition of white. He carried out an experiment in which a beam from a light source was passed through a narrow slit, behind which a lens was placed. From it, a beam of light was redirected to a prism, where it was refracted and disintegrated into components.
Remember that a prism is a polyhedron with a base, the sides of which form a volumetric figure. A drop of water is a real prism. Falling through it, a ray of the sun refracts and turns into a rainbow.
Sunlight is split in different ways because each wave in the spectrum has a different length. Distinctive feature is the fact that two observers standing side by side will each see their own rainbow.
The effect will occur due to the fact that the drops cannot be the same, and the arrangement of colors, their brightness, the width of the rainbow arcs directly depend on the size and shape of the drops.
If you want to see the rainbow in all its glory, you need the sun to shine on your back. The rainbow will be brighter and more saturated if the light is refracted through large drops, if they are small, the arcs will be wider, but their color is less bright. It so happens that when falling raindrops become flattened, in this case the radius of the rainbow will be small. If the drops stretch out when falling, then the rainbow will be high, but its colors are pale.
The rainbow is one of the most amazing natural phenomena. People have been thinking about the essence of this phenomenon for a long time. The rainbow is the companion of the rain. The time of its appearance depends on the movement of the cloud giving rainfall. A rainbow can appear both before the rain, and during the precipitation process, or at the end of the process.
What is a rainbow?
Typically, a rainbow is a colored arc with an angular radius of 42 °. The arc is visible against the background of a curtain of rain or streaks of rain falling, which do not always reach the surface of the earth. A rainbow is observed in the opposite side of the sky to the sun, and the sun is not obscured by clouds. Most often, such conditions are created in summer, during the so-called "mushroom" rains. The center of the rainbow is the antisolar point - this point is diametrically opposite to the Sun. The rainbow is distinguished by seven colors, in addition, the rainbow can be seen near a fountain or waterfall, against the background of a curtain of drops of an irrigation system.
Where does the amazing colorful light emanating from the rainbow come from? The source of the rainbow is the decomposed sunlight. This light moves across the firmament in such a way that it is seen as emanating from that part of the firmament that is opposite to the sun. The main features of the rainbow are correctly explained by the Descartes-Newton theory, created more than 300 years ago.
An object capable of breaking down a ray of light into its components is called a "prism". If we talk about a rainbow, then the role of a "prism" is played by raindrops. A rainbow is a large curved spectrum or a strip of colored lines formed as a result of the decomposition of a ray of light passing through raindrops. The colors go in the following order, if you count from the outer to the inner radius (it is quite easy to memorize this spectrum by learning a simple acrostic phrase: "Every hunter wants to know where the pheasant is sitting", here the first letter of each word corresponds to the first letter of the color):
One is Red;
Hunter - Orange;
Desires - Yellow;
Know - Green;
Where - Blue;
Sitting - Blue;
Pheasant - Purple.
The rainbow can be seen at a time when the sun is shining in parallel with the shower. To see it, you need to be strictly between the sun and rain. In this case, the Sun should be in the back, and the rain in front.
Quick answer: there are 7 colors in total in the rainbow.
What is a rainbow? This is an optical phenomenon that can be observed when the sun (and in some cases the moon) illuminates a large number of water droplets (we are talking about fog or water). A rainbow is an arc-shaped circle with seven spectrum colors: blue, purple, green, cyan, orange, yellow, and red. It is worth noting that the Sun at the time of observing the rainbow is always behind the back of the observer, therefore, it is impossible to see both of them at the same time, unless with the help of special equipment.
Where does this optical phenomenon come from? It arises from the refraction of light in water droplets that float in the atmosphere. The droplets tend to deflect light of different colors in different ways. White color decomposes into a spectrum, resulting in the dispersion of light - the refraction of matter, depending on the frequency or phase speed of light. Roughly speaking, sunny color passes through the smallest droplets of water, refracts and is visible to the human eye as several colors at once.
There are two types of rainbows - primary and secondary. In the first case, the light inside the drop is reflected only once, the shades in this case are quite bright. In the second case, the light is reflected twice and the colors that our eyes take are no longer so bright. There is also a rainbow of the third, and even fourth order, but no one has personally observed this miracle of nature for several centuries.
It should be noted that the colors in the rainbow are arranged in the sequence that corresponds to the spectrum visible light... To memorize them, some countries have even invented such rhymes and phrases. Russia is no exception. In our country, several phrases are used at once, here they are:
- How once Jacques the bell-ringer broke a lantern with his head.
- Every hunter wants to know where the pheasant is sitting.
- A mole, a sheep, a giraffe, a blue hare, sewed sweatshirts.
- Every designer wants to know where to download photoshop.
- Who senses the cruel ringing of the gong of resistance to fatality?
- The quark is surrounded by a hot curtain of gluons that create fluids.
As you might guess, the initial letter of each word denotes the initial letter of the color:
- Like - red.
- One day - orange.
- Jacques is yellow.
- The bell ringer is green.
- The head is blue.
- Broke - blue.
- The lantern is purple.
The rainbow is an amazing and incredibly beautiful meteorological and optical natural phenomenon. It can be seen mainly after rain, when the sun comes out. This is the reason that we can see this wonderful phenomenon in the sky, as well as distinguish the colors of the rainbow, in order.
Causes of occurrence
A rainbow occurs when light emanating from the sun or from another source is refracted in droplets of water that slowly fall to the ground. With their help, white light "breaks", forming the colors of the rainbow. They are arranged in order due to different degrees of light deflection (for example, red light is deflected by fewer degrees than violet). Moreover, a rainbow can also appear due to moonlight, but it is very difficult for our eye to distinguish it in low light. When forming a circle, which is formed by the "heavenly bridge", the center is always on a straight line passing through the Sun or Moon. For those who observe this phenomenon from the ground, this "bridge" appears as an arc. But the higher the vantage point, the fuller the rainbow is seen. If you observe it from a mountain or from the air, it can appear before your eyes in the form of a whole circle.
Rainbow color order
Many people know a phrase that allows you to remember the order in which the colors of the rainbow are located. For those who do not know or do not remember, let us recall how this line sounds: "Every Hunter Wants to Know Where the Pheasant Sits" (by the way, now there are many analogs to this famous monostikh, more modern and sometimes very funny). The colors of the rainbow are in order: red, orange, yellow, green, light blue, blue and purple.
These colors do not change their location, capturing in memory the eternal appearance of such an incredibly beautiful phenomenon. The rainbow we see often is primary. During its formation, white light undergoes only one internal reflection. In this case, the red light is outside, as we are used to seeing. However, a secondary rainbow can also form. This is a rather rare occurrence in which white light is reflected twice in droplets. In this case, the colors of the rainbow are already in order in the opposite direction (from purple to red). At the same time, the part of the sky that is between these two arcs becomes darker. In places with very clean air, you can even observe a "triple" rainbow.
Unusual rainbows
In addition to the familiar rainbow in the form of an arc, you can observe its other forms. For example, you can observe lunar rainbows (but it is difficult for the human eye to catch them, for this the glow from the moon must be very bright), foggy, ring-shaped (these phenomena have already been mentioned above) and even inverted. In addition, the rainbow can be observed in winter. At this time of the year, it sometimes occurs due to severe frosts. But some of these phenomena have nothing to do with "heavenly bridges". It is very often mistaken for a rainbow (this is the name of a luminous ring that forms around a certain object).