Physics is the science of nature. Physical bodies and physical phenomena - Hypermarket of knowledge. Optical phenomena: examples in nature and interesting facts Types of physical phenomena with examples

Physical bodies are the “actors” of physical phenomena. Let's get to know some of them.

Mechanical phenomena

Mechanical phenomena are the movement of bodies (Fig. 1.3) and their action on each other, for example repulsion or attraction. The action of bodies on each other is called interaction.

We will get to know mechanical phenomena in more detail this academic year.

Rice. 1.3. Examples of mechanical phenomena: movement and interaction of bodies during sports competitions (a, b. c); movement of the Earth around the Sun and its rotation around its own axis (r)

Sound phenomena

Sound phenomena, as the name suggests, are phenomena involving sound. These include, for example, the propagation of sound in air or water, as well as the reflection of sound from various obstacles - say, mountains or buildings. When sound is reflected, a familiar echo appears.

Thermal phenomena

Thermal phenomena are the heating and cooling of bodies, as well as, for example, evaporation (the transformation of a liquid into steam) and melting (the transformation of a solid into a liquid).

Thermal phenomena are extremely widespread: for example, they determine the water cycle in nature (Fig. 1.4).

Rice. 1.4. Water cycle in nature

The water of the oceans and seas, heated by the sun's rays, evaporates. As the steam rises, it cools, turning into water droplets or ice crystals. They form clouds from which water returns to Earth in the form of rain or snow.

The real “laboratory” of thermal phenomena is the kitchen: whether soup is being cooked on the stove, whether water is boiling in a kettle, whether food is frozen in the refrigerator - all these are examples of thermal phenomena.

The operation of a car engine is also determined by thermal phenomena: when gasoline burns, a very hot gas is formed, which pushes the piston (motor part). And the movement of the piston is transmitted through special mechanisms to the wheels of the car.

Electrical and magnetic phenomena

The most striking (in the literal sense of the word) example of an electrical phenomenon is lightning (Fig. 1.5, a). Electric lighting and electric transport (Fig. 1.5, b) became possible thanks to the use of electrical phenomena. Examples of magnetic phenomena are the attraction of iron and steel objects by permanent magnets, as well as the interaction of permanent magnets.

Rice. 1.5. Electrical and magnetic phenomena and their uses

The compass needle (Fig. 1.5, c) rotates so that its “north” end points north precisely because the needle is a small permanent magnet, and the Earth is a huge magnet. The Northern Lights (Fig. 1.5, d) are caused by the fact that electrically charged particles flying from space interact with the Earth as with a magnet. Electrical and magnetic phenomena determine the operation of televisions and computers (Fig. 1.5, e, f).

Optical phenomena

Wherever we look, we will see optical phenomena everywhere (Fig. 1.6). These are phenomena associated with light.

An example of an optical phenomenon is the reflection of light by various objects. Rays of light reflected by objects enter our eyes, thanks to which we see these objects.

Rice. 1.6. Examples of optical phenomena: The sun emits light (a); The moon reflects sunlight (b); Mirrors (c) reflect light especially well; one of the most beautiful optical phenomena - rainbow (d)

We are surrounded by an infinitely diverse world of substances and phenomena.

Changes are constantly taking place in it.

Any changes that occur to bodies are called phenomena. The birth of stars, the change of day and night, the melting of ice, the swelling of buds on trees, the flash of lightning during a thunderstorm, and so on - all these are natural phenomena.

Let us remember that bodies are made of substances. Note that during some phenomena the substances of bodies do not change, but during others they do. For example, if you tear a piece of paper in half, then, despite the changes that have occurred, the paper will remain paper. If you burn the paper, it will turn into ash and smoke.

Phenomena in which the size, shape of bodies, the state of substances may change, but substances remain the same, do not transform into others, are called physical phenomena(evaporation of water, glow of a light bulb, sound of the strings of a musical instrument, etc.).

Physical phenomena are extremely diverse. Among them there are mechanical, thermal, electrical, light and etc.

Let's remember how clouds float across the sky, an airplane flies, a car drives, an apple falls, a cart rolls, etc. In all of the above phenomena, objects (bodies) move. Phenomena associated with a change in the position of a body in relation to other bodies are called mechanical(translated from Greek “mechane” means machine, weapon).

Many phenomena are caused by alternating heat and cold. In this case, changes occur in the properties of the bodies themselves. They change shape, size, the state of these bodies changes. For example, when heated, ice turns into water, water into steam; When the temperature drops, steam turns into water, and water into ice. Phenomena associated with heating and cooling of bodies are called thermal(Fig. 35).

Rice. 35. Physical phenomenon: transition of a substance from one state to another. If you freeze drops of water, ice will form again

Let's consider electric phenomena. The word "electricity" comes from the Greek word "electron" - amber. Remember that when you quickly take off your wool sweater, you hear a slight cracking noise. If you do the same in complete darkness, you will also see sparks. This is the simplest electrical phenomenon.

To get acquainted with another electrical phenomenon, do the following experiment.

Tear small pieces of paper and place them on the table surface. Comb clean and dry hair with a plastic comb and hold it to the pieces of paper. What happened?

Rice. 36. Small pieces of paper are attracted to the comb

Bodies that are capable of attracting light objects after rubbing are called electrified(Fig. 36). Lightning during a thunderstorm, auroras, electrification of paper and synthetic fabrics are all electrical phenomena. The operation of the telephone, radio, television, and various household appliances are examples of human use of electrical phenomena.

Phenomena that are associated with light are called light phenomena. Light is emitted by the Sun, stars, lamps and some living creatures, such as fireflies. Such bodies are called glowing.

We see under the condition of exposure to light on the retina of the eye. In absolute darkness we cannot see. Objects that do not themselves emit light (for example, trees, grass, the pages of this book, etc.) are visible only when they receive light from some luminous body and reflect it from their surface.

The moon, which we often talk about as a night luminary, is in fact only a kind of reflector of sunlight.

By studying the physical phenomena of nature, man learned to use them in everyday life.

1. What are called natural phenomena?

2. Read the text. List what natural phenomena are named in it: “Spring has come. The sun is getting hotter and hotter. The snow is melting, streams are flowing. The buds on the trees have swelled and the rooks have arrived.”

3. What phenomena are called physical?

4. From the physical phenomena listed below, write down the mechanical phenomena in the first column; in the second - thermal; in the third - electric; in the fourth – light phenomena.

Physical phenomena: flash of lightning; snow melting; coast; melting metals; operation of an electric bell; rainbow in the sky; sunny bunny; moving stones, sand with water; boiling water.

Since ancient times, mirages and flickering figures in the air have alarmed and terrified people. Nowadays, scientists have uncovered many secrets of nature, including optical phenomena. They are not surprised by natural mysteries, the essence of which has long been studied. In high school today, optical phenomena are taught in physics in the 8th grade, so any student can understand their nature.

Basic Concepts

Scientists of antiquity believed that the human eye sees by feeling objects with the thinnest tentacles. Optics at that time was the study of vision.

In the Middle Ages, optics studied light and its essence.

Today, optics is a branch of physics that studies the propagation of light through various media and its interaction with other substances. All issues related to vision are studied by physiological optics.

Optical phenomena are manifestations of diverse actions performed by rays of light. They are studied by atmospheric optics.

Unusual processes in the atmosphere

Planet Earth is surrounded by a gaseous shell called the atmosphere. Its thickness is hundreds of kilometers. Closer to the Earth, the atmosphere is denser, and thins upward. The physical properties of the atmospheric shell are constantly changing, the layers are mixed. Change temperature indicators. Density and degree of transparency shift.

Light rays come from the Sun and other celestial bodies towards the Earth. They pass through the Earth's atmosphere, which for them serves as a specific optical system that changes its characteristics. are reflected, scattered, pass through the atmosphere, and illuminate the earth. Under certain conditions, the path of the rays bends, so various phenomena arise. Physicists consider the most original optical phenomena to be:

• sunset of the sun;
• the appearance of a rainbow;
• northern lights;
• mirage;
• halo.

Let's take a closer look at them.

Halo around the Sun

The word “halo” itself means “circle” in Greek. What optical phenomenon underlies it?

A halo is a process of light refraction and reflection that occurs in cloud crystals high in the atmosphere. The phenomenon looks like luminous rays near the Sun, limited to a dark interval. Halos usually form before cyclones and can be their precursors.

Water droplets freeze in the air and take on a regular prismatic shape with six sides. Everyone is familiar with icicles appearing in the lower atmospheric layers. At the top, such ice needles freely fall in the vertical direction. Crystalline ice floes swirl and descend to the ground, while they are parallel to the ground. A person directs vision through crystals, which act as lenses and refract light.

Other prisms are flat or look like stars with six rays. Rays of light hitting the crystals may not undergo refraction or undergo a number of other processes. It rarely happens that all processes are clearly visible; usually one or another part of the phenomenon appears more clearly, while others are poorly represented.

The minor halo is a circle around the sun with a radius of approximately 22 degrees. The color of the circle is reddish from the inside, then flows into yellow, white and mixes with the blue sky. The inner area of ​​the circle is dark. It is formed as a result of light refraction in ice needles flying in the air. The rays in the prisms are deflected at an angle of 22 degrees, so those that passed through the crystals appear to the observer deflected by 22 degrees. Therefore it appears dark.

Red color is refracted less and appears least deviated from the sun. Next comes yellow. Other rays mix and appear white to the eye.

There is a halo with an angle of 46 degrees, it is located around a halo of 22 degrees. Its inner region is also reddish because light undergoes refraction in the ice needles, which are turned 90 degrees toward the sun.

A 90-degree halo is also known; it glows faintly, has almost no color or is colored red on the outside. Scientists have not yet fully studied this species.

Halo around the Moon and other types

This optical phenomenon is often visible if there are light clouds and many miniature crystalline ice floes in the sky. Each such crystal is a kind of prism. Basically their shape is elongated hexagons. Light enters the front crystalline region and exits the opposite region and is refracted 22 degrees.

In winter, you can see a halo in the cold air near street lamps. It appears due to the light of a lantern.

A halo can also form around the Sun in frosty, snowy air. Snowflakes are in the air, light passes through the clouds. At sunset this light turns red. In past centuries, superstitious people were horrified by such phenomena.

A halo may appear as a rainbow-colored circle around the Sun. It appears if there are many crystals with six sides in the atmosphere, but they do not reflect, but refract the rays of the sun. Most of the rays are scattered, not reaching our gaze. The remaining rays reach human eyes, and we notice a rainbow circle around the Sun. Its radius is approximately 22 degrees or 46 degrees.

False Sun

Scientists noted that the halo circle is always brighter on the sides. This is explained by the fact that a vertical and horizontal halo meet here. False suns may appear where they intersect. This happens especially often when the Sun is close to the horizon, at which time we no longer see part of the vertical circle.

A false sun is also an optical phenomenon, a type of halo. It appears due to ice crystals with six sides, shaped like nails. Such crystals float in the atmosphere in a vertical direction, light is refracted at their side faces.

A third “sun” may also form if only the superficial part of the halo circle is visible above the true sun. It can be a segment of an arc or a luminous spot of an incomprehensible shape. Sometimes false suns are so bright that they cannot be distinguished from the real Sun.

Rainbow

This is the form of an incomplete circle with different colors.

Religions of antiquity were considered from heaven to earth. Aristotle believed that a rainbow appears due to the reflection of drops of sunlight. What other optical phenomenon can delight a person as much as a rainbow does?

In the 17th century, Descartes studied the nature of the rainbow. Later, Newton conducted experiments with light and expanded Descartes' theory, but could not understand the formation of several rainbows and the absence of individual color shades in them.

The complete theory of the rainbow was presented in the 19th century by the English astronomer D. Airy. It was he who managed to reveal all the processes of the rainbow. The theory he developed is still accepted today.

A rainbow appears when the light of the sun hits a curtain of rainwater in the area of ​​the sky opposite the Sun. The center of the rainbow is located at a point on the opposite side of the Sun, that is, it is not visible to the human eye. The arc of the rainbow is the part of the circle around this central point.

The colors in the rainbow are placed in a specific order. He is constant. Red - along the top edge, purple - along the bottom. Between them, the colors are in a strict arrangement. The rainbow does not contain all existing colors. The predominance of green color indicates a transition to favorable weather.

Polar Lights

This is a glow in the upper magnetic layers of the atmosphere due to the interaction of atoms and elements of the solar wind. Typically, auroras have green or blue hues interspersed with pink and red. They may be in the form of a ribbon or a spot. Their bursts are often accompanied by noisy sounds.

Mirage

Simple mirage deceptions are familiar to any person. For example, when driving on heated asphalt, a mirage appears as This does not surprise anyone. What optical phenomenon explains the appearance of mirages? Let's look at this issue in more detail.

A mirage is an optical physical phenomenon in the atmosphere, as a result of which the eye sees objects hidden from view under normal conditions. This is explained by the refraction of a light beam as it flows through air layers. Objects located at a considerable distance may rise or fall relative to their true location, or may become distorted and take on bizarre shapes.

Brocken Ghost

This is a phenomenon in which, at sunset or sunrise, the shadow of a person located on a hill acquires incomprehensible proportions, as it falls on clouds nearby. This is due to the reflection and refraction of light rays by water droplets in foggy conditions. The phenomenon was named after one of the heights of the German Harz Mountains.

St. Elmo's Fire

These are luminous brushes of blue or purple color on the masts of sea vessels. Lights can appear on mountainous heights, on buildings of impressive height. This phenomenon occurs due to electrical discharges at the ends of the conductors due to the fact that the electrical tension increases.

These are the optical phenomena discussed in 8th grade lessons. Let's talk about optical devices.

Designs in optics

Optical devices are devices that convert light radiation. Typically these devices operate in visible light.

All optical devices can be divided into two types:

1. Devices in which an image is produced on a screen. These are cameras, movie cameras, projection devices.
2. Devices that interact with the human eye but do not produce images on the screen. These are magnifying glasses, microscopes, telescopes. These devices are considered visual.

A camera is an optical-mechanical device used to obtain images of an object on photographic film. The design of the camera includes a camera and lenses that form the lens. The lens creates an inverted, reduced image of the object, captured on film. This occurs due to the action of light.

The image is initially invisible, but thanks to the developing solution it becomes visible. This image is called a negative, in which light areas appear dark and vice versa. The negative is turned into a positive on photosensitive paper. Using a photo enlarger, the image is enlarged.

A magnifying glass is a lens or lens system designed to magnify objects while viewing them. The magnifying glass is placed next to the eye, and the distance from which the object can be seen clearly is selected. The use of a magnifying glass is based on increasing the angle of view from which an object is viewed.

To obtain greater angular magnification, a microscope is used. In this device, objects are magnified thanks to an optical system consisting of a lens and an eyepiece. First, the angle of view is increased by the lens, then by the eyepiece.

So, we examined the main optical phenomena and devices, their varieties and features.

“Optical phenomena in nature”

1. Introduction

a) The concept of optics

b) Classification of optics

c) Optics in the development of modern physics

2. Phenomena associated with the reflection of light

4. Auroras

Introduction

Optics concept

The first ideas of ancient scientists about light were very naive. They thought that visual impressions arise when objects are felt with special thin tentacles that come out of the eyes. Optics was the science of vision, this is how this word can most accurately be translated.

Gradually in the Middle Ages, optics turned from the science of vision into the science of light, facilitated by the invention of lenses and the camera obscura. At the present time, optics is a branch of physics that studies the emission of light and its propagation in various media, as well as its interaction with matter. Issues related to vision, the structure and functioning of the eye, became a separate scientific field - physiological optics.

Optics classification

Light rays are geometric lines along which light energy propagates; when considering many optical phenomena, you can use the idea of ​​them. In this case, we talk about geometric (ray) optics. Geometric optics has become widespread in lighting engineering, as well as when considering the actions of numerous instruments and devices - from magnifying glasses and glasses to the most complex optical telescopes and microscopes.

Intensive research into the previously discovered phenomena of interference, diffraction and polarization of light began at the beginning of the 19th century. These processes were not explained within the framework of geometric optics, so it was necessary to consider light in the form of transverse waves. As a result, wave optics appeared. Initially, it was believed that light is elastic waves in a certain medium (world ether) filling the world space.

But the English physicist James Maxwell in 1864 created the electromagnetic theory of light, according to which light waves are electromagnetic waves with a corresponding range of lengths.

And already at the beginning of the 20th century, new studies showed that in order to explain some phenomena, for example the photoelectric effect, there is a need to represent a light beam in the form of a stream of peculiar particles - light quanta. Isaac Newton had a similar view on the nature of light 200 years ago in his “theory of the effusion of light.” Now quantum optics is doing this.

The role of optics in the development of modern physics.

Optics also played a significant role in the development of modern physics. The emergence of two of the most important and revolutionary theories of the twentieth century (quantum mechanics and the theory of relativity) is connected in principle with optical research. Optical methods for analyzing matter at the molecular level have given rise to a special scientific field - molecular optics, which also includes optical spectroscopy, used in modern materials science, plasma research, and astrophysics. There are also electron and neutron optics.

At the present stage of development, an electron microscope and a neutron mirror have been created, and optical models of atomic nuclei have been developed.

Optics, influencing the development of various areas of modern physics, is itself today in a period of rapid development. The main impetus for this development was the invention of lasers - intense sources of coherent light. As a result, wave optics rose to a higher level, the level of coherent optics.

Thanks to the advent of lasers, many scientific and technical developing areas have emerged. Among which are nonlinear optics, holography, radio optics, picosecond optics, adaptive optics, etc.

Radio optics originated at the intersection of radio engineering and optics and deals with the study of optical methods for transmitting and processing information. These methods are combined with traditional electronic methods; The result was a scientific and technical direction called optoelectronics.

The subject of fiber optics is the transmission of light signals through dielectric fibers. Using the achievements of nonlinear optics, it is possible to change the wavefront of a light beam, which is modified as light propagates in a particular medium, for example, in the atmosphere or in water. Consequently, adaptive optics has emerged and is being intensively developed. Closely related to this is photoenergetics, which is emerging before our eyes and deals, in particular, with the issues of efficient transmission of light energy along a beam of light. Modern laser technology makes it possible to produce light pulses with a duration of only picoseconds. Such pulses turn out to be a unique “tool” for studying a number of fast processes in matter, and in particular in biological structures. A special direction has emerged and is being developed – picosecond optics; Photobiology is closely related to it. It can be said without exaggeration that the widespread practical use of the achievements of modern optics is a prerequisite for scientific and technological progress. Optics opened the way to the microcosm for the human mind, and it also allowed it to penetrate the secrets of the stellar worlds. Optics covers all aspects of our practice.

Phenomena associated with the reflection of light.

The object and its reflection

The fact that the landscape reflected in still water does not differ from the real one, but is only turned upside down, is far from true.

If a person looks late in the evening at how lamps are reflected in the water or how the shore descending to the water is reflected, then the reflection will seem shortened to him and will completely “disappear” if the observer is high above the surface of the water. Also, you can never see the reflection of the top of a stone, part of which is immersed in water.

The landscape appears to the observer as if it were viewed from a point located as much below the surface of the water as the observer's eye is above the surface. The difference between the landscape and its image decreases as the eye approaches the surface of the water, and also as the object moves away.

People often think that the reflection of bushes and trees in a pond has brighter colors and richer tones. This feature can also be noticed by observing the reflection of objects in a mirror. Here psychological perception plays a greater role than the physical side of the phenomenon. The frame of the mirror and the banks of the pond limit a small area of ​​the landscape, protecting a person’s lateral vision from excess scattered light coming from the entire sky and blinding the observer, that is, he looks at a small area of ​​the landscape as if through a dark narrow pipe. Reducing the brightness of reflected light compared to direct light makes it easier for people to observe the sky, clouds and other brightly lit objects that, when directly observed, are too bright for the eye.

Dependence of reflection coefficient on the angle of incidence of light.

At the boundary of two transparent media, light is partially reflected, partially passes into another medium and is refracted, and partially absorbed by the medium. The ratio of reflected energy to incident energy is called the reflection coefficient. The ratio of the energy of light transmitted through a substance to the energy of incident light is called transmittance.

Reflection and transmittance coefficients depend on the optical properties, the adjacent media and the angle of incidence of light. So, if light falls on a glass plate perpendicularly (angle of incidence α = 0), then only 5% of the light energy is reflected, and 95% passes through the interface. As the angle of incidence increases, the fraction of reflected energy increases. At the angle of incidence α=90˚ it is equal to unity.

The dependence of the intensity of light reflected and transmitted through a glass plate can be traced by placing the plate at different angles to the light rays and assessing the intensity by eye.

It is also interesting to evaluate by eye the intensity of light reflected from the surface of a reservoir, depending on the angle of incidence, to observe the reflection of the sun's rays from the windows of a house at different angles of incidence during the day, at sunset, and at sunrise.

Safety glass

Conventional window glass partially transmits heat rays. This is good for use in northern areas, as well as for greenhouses. In the south, the rooms become so overheated that it is difficult to work in them. Protection from the Sun comes down to either shading the building with trees, or choosing a favorable orientation of the building during reconstruction. Both are sometimes difficult and not always feasible.

To prevent glass from transmitting heat rays, it is coated with thin transparent films of metal oxides. Thus, a tin-antimony film does not transmit more than half of thermal rays, and coatings containing iron oxide completely reflect ultraviolet rays and 35-55% of thermal rays.

Solutions of film-forming salts are applied from a spray bottle to the hot surface of the glass during its heat treatment or molding. At high temperatures, salts transform into oxides, tightly bound to the surface of the glass.

Glasses for sunglasses are made in a similar way.

Total internal reflection of light

A beautiful sight is the fountain, whose ejected jets are illuminated from within. This can be depicted under normal conditions by performing the following experiment (Fig. 1). In a tall tin can, drill a round hole at a height of 5 cm from the bottom ( A) 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 A, we get a jet that will be illuminated from within. In a dark room it glows brightly and looks very impressive. The stream can be given any color by placing colored glass in the path of the light rays b. If you put your finger in the path of the stream, the water splashes and these droplets glow brightly.

The explanation for this phenomenon is quite simple. A ray of light passes along a stream of water and hits a curved surface at an angle greater than the limiting one, experiences total internal reflection, and then again hits the opposite side of the stream at an angle again greater than the limiting one. So the beam passes along the jet, bending along with it.

But if the light were completely reflected inside the jet, then it would not be visible from the outside. Part of the light is scattered by water, air bubbles and various impurities present in it, as well as due to the uneven surface of the jet, so it is visible from the outside.

Cylindrical light guide

If you direct a light beam at one end of a solid glass curved cylinder, you will notice that light will come out of its other end (Fig. 2); Almost no light comes out through the side surface of the cylinder. The passage of light through a glass cylinder is explained by the fact that, falling on the inner surface of the cylinder at an angle greater than the limiting one, the light undergoes complete reflection many times and reaches the end.

The thinner the cylinder, the more often the beam will be reflected and the larger part of the light will fall on the inner surface of the cylinder at angles greater than the limiting one.

Diamonds and gems

There is an exhibition of the Russian diamond fund in the Kremlin.

The light in the hall is slightly dimmed. The jewelers' creations sparkle in the windows. Here you can see such diamonds as “Orlov”, “Shah”, “Maria”, “Valentina Tereshkova”.

The secret of the wonderful play of light in diamonds is that this stone has a high refractive index (n=2.4173) and, as a result, a small angle of total internal reflection (α=24˚30′) and has greater dispersion, causing the decomposition of white light to simple colors.

In addition, the play of light in a diamond depends on the correctness of its cut. The facets of a diamond reflect light multiple times within the crystal. Due to the great transparency of high-class diamonds, the light inside them almost does not lose its energy, but only decomposes into simple colors, the rays of which then burst out in various, most unexpected directions. When you turn the stone, the colors emanating from the stone change, and it seems that it itself is the source of many bright multi-colored rays.

There are diamonds colored red, bluish and lilac. The shine of a diamond depends on its cut. If you look through a well-cut water-transparent diamond into the light, the stone appears completely opaque, and some of its facets appear simply black. This happens because the light, undergoing total internal reflection, comes out in the opposite direction or to the sides.

When viewed from the side of the light, the top cut shines with many colors and is shiny in places. The bright sparkle of the upper edges of a diamond is called diamond luster. The underside of the diamond appears to be silver-plated from the outside and has a metallic sheen.

The most transparent and large diamonds serve as decoration. Small diamonds are widely used in technology as a cutting or grinding tool for metalworking machines. Diamonds are used to reinforce the heads of drilling tools for drilling wells in hard rocks. This use of diamond is possible due to its great hardness. Other precious stones in most cases are crystals of aluminum oxide with an admixture of oxides of coloring elements - chromium (ruby), copper (emerald), manganese (amethyst). They are also distinguished by hardness, durability and have beautiful colors and “play of light”. Currently, they are able to artificially obtain large crystals of aluminum oxide and paint them in the desired color.

The phenomena of light dispersion are explained by the variety of colors of nature. A whole set of optical experiments with prisms was carried out by the English scientist Isaac Newton in the 17th century. These experiments showed that white light is not fundamental, it should be considered as composite (“inhomogeneous”); the main ones are different colors (“uniform” rays, or “monochromatic” rays). The decomposition of white light into different colors occurs because each color has its own degree of refraction. These conclusions made by Newton are consistent with modern scientific ideas.

Along with the dispersion of the refractive index, dispersion of the absorption, transmission and reflection coefficients of light is observed. This explains the various effects when illuminating bodies. For example, if there is some body transparent to light, for which the transmittance coefficient is large for red light and the reflection coefficient is small, but for green light it is the opposite: the transmittance coefficient is small and the reflection coefficient is large, then in transmitted light the body will appear red, and in reflected light it is green. Such properties are possessed, for example, by chlorophyll, a green substance contained in plant leaves and responsible for its green color. A solution of chlorophyll in alcohol appears red when viewed against light. In reflected light, the same solution appears green.

If a body has a high absorption coefficient and low transmittance and reflection coefficients, then such a body will appear black and opaque (for example, soot). A very white, opaque body (eg magnesium oxide) has a reflectance close to unity for all wavelengths, and very low transmittance and absorption coefficients. A body (glass) that is completely transparent to light has low reflection and absorption coefficients and a transmittance close to unity for all wavelengths. In colored glass, for some wavelengths the transmittance and reflection coefficients are practically equal to zero and, accordingly, the absorption coefficient for the same wavelengths is close to unity.

Phenomena associated with the refraction of light

Some types of mirages. From the larger variety of mirages, we will single out several types: “lake” mirages, also called lower mirages, upper mirages, double and triple mirages, ultra-distant vision mirages.

Lower (“lake”) mirages appear above a very heated surface. Superior mirages, on the contrary, appear over a very cool surface, for example over cold water. If the lower mirages are observed, as a rule, in deserts and steppes, then the upper ones are observed in northern latitudes.

The upper mirages are diverse. In some cases they give a direct image, in other cases an inverted image appears in the air. Mirages can be double, when two images are observed, one simple and one inverted. These images may be separated by a strip of air (one may be above the horizon line, the other below it), but may directly merge with each other. Sometimes another one appears - a third image.

Ultra-long-range vision mirages are especially amazing. K. Flammarion in his book “Atmosphere” describes an example of such a mirage: “Based on the testimony of several trustworthy persons, I can report on a mirage that was seen in the city of Verviers (Belgium) in June 1815. One morning, residents of the city saw in the sky army, and it was so clear that one could distinguish the suits of the artillerymen and even, for example, a cannon with a broken wheel that was about to fall off... It was the morning of the Battle of Waterloo!” The described mirage is depicted in the form of a colored watercolor by one of the eyewitnesses. The distance from Waterloo to Verviers in a straight line is more than 100 km. There are known cases when similar mirages were observed at large distances - up to 1000 km. “The Flying Dutchman” should be attributed precisely to such mirages.

Explanation of the lower (“lake”) mirage. If the air near the surface of the earth is very hot and, therefore, its density is relatively low, then the refractive index at the surface will be less than in higher air layers. Changing the refractive index of air n with height h near the earth's surface for the case under consideration is shown in Figure 3, a.

In accordance with the established rule, light rays near the surface of the earth will in this case be bent so that their trajectory is convex downward. Let there be an observer at point A. A light ray from a certain area of ​​​​the blue sky will enter the observer's eye, experiencing the specified curvature. This means that the observer will see the corresponding section of the sky not above the horizon line, but below it. It will seem to him that he sees water, although in fact there is an image of blue sky in front of him. If we imagine that there are hills, palm trees or other objects near the horizon line, then the observer will see them upside down, thanks to the noted curvature of the rays, and will perceive them as reflections of the corresponding objects in non-existent water. This is how an illusion arises, which is a “lake” mirage.

Simple superior mirages. It can be assumed that the air at the very surface of the earth or water is not heated, but, on the contrary, is noticeably cooled compared to higher air layers; the change in n with height h is shown in Figure 4, a. In the case under consideration, the light rays are bent so that their trajectory is convex upward. Therefore, now the observer can see objects hidden from him behind the horizon, and he will see them at the top, as if hanging above the horizon line. Therefore, such mirages are called upper.

The superior mirage can produce both an upright and an inverted image. The direct image shown in the figure occurs when the refractive index of air decreases relatively slowly with height. When the refractive index decreases rapidly, an inverted image is formed. This can be verified by considering a hypothetical case - the refractive index at a certain height h decreases abruptly (Fig. 5). The rays of the object, before reaching observer A, experience total internal reflection from the boundary BC, below which in this case there is denser air. It can be seen that the superior mirage gives an inverted image of the object. In reality, there is no abrupt boundary between the layers of air; the transition occurs gradually. But if it occurs sharply enough, then the superior mirage will give an inverted image (Fig. 5).

Double and triple mirages. If the refractive index of air changes first quickly and then slowly, then in this case the rays in region I will bend faster than in region II. As a result, two images appear (Fig. 6, 7). Light rays 1 propagating within the air region I form an inverted image of the object. Rays 2, which propagate mainly within region II, are bent to a lesser extent and form a straight image.

To understand how a triple mirage appears, you need to imagine three successive air regions: the first (near the surface), where the refractive index decreases slowly with height, the next, where the refractive index decreases quickly, and the third region, where the refractive index decreases again slowly. The figure shows the considered change in the refractive index with height. The figure shows how a triple mirage occurs. Rays 1 form the lower image of the object, they extend within the air region I. Rays 2 form an inverted image; I fall into air region II, these rays experience strong curvature. Rays 3 form the upper direct image of the object.

Ultra-long-range vision mirage. The nature of these mirages is least studied. It is clear that the atmosphere must be transparent, free of water vapor and pollution. But this is not enough. A stable layer of cooled air should form at a certain height above the earth's surface. Below and above this layer the air should be warmer. A light beam that gets inside a dense cold layer of air is, as it were, “locked” inside it and spreads through it as if through a kind of light guide. The beam path in Figure 8 is always convex towards less dense areas of air.

The occurrence of ultra-long-range mirages can be explained by the propagation of rays inside similar “light guides”, which nature sometimes creates.

Rainbow is a beautiful celestial phenomenon that has always attracted human attention. In former times, when people still knew little about the world around them, the rainbow was considered a “heavenly sign.” So, the ancient Greeks thought that the rainbow was the smile of the goddess Iris.

A rainbow is observed in the direction opposite to the Sun, against the background of rain clouds or rain. The multi-colored arc is usually located at a distance of 1-2 km from the observer, and sometimes it can be observed at a distance of 2-3 m against the background of water drops formed by fountains or water sprays.

The center of the rainbow is located on the continuation of the straight line connecting the Sun and the observer's eye - on the antisolar line. The angle between the direction towards the main rainbow and the anti-solar line is 41-42º (Fig. 9).

At the moment of sunrise, the antisolar point (point M) is on the horizon line and the rainbow has the appearance of a semicircle. As the Sun rises, the antisolar point moves below the horizon and the size of the rainbow decreases. It represents only part of a circle.

A secondary rainbow is often observed, concentric with the first, with an angular radius of about 52º and the colors in reverse.

When the Sun's altitude is 41º, the main rainbow ceases to be visible and only part of the side rainbow protrudes above the horizon, and when the Sun's altitude is more than 52º, the side rainbow is not visible either. Therefore, in mid-equatorial latitudes this natural phenomenon is never observed during the midday hours.

The rainbow has seven primary colors, smoothly transitioning from one to another.

The type of arc, the brightness of the colors, and the width of the stripes depend on the size of the water droplets and their number. Large drops create a narrower rainbow, with sharply prominent colors, small drops create a blurry, faded and even white arc. That is why a bright narrow rainbow is visible in the summer after a thunderstorm, during which large drops fall.

The rainbow theory was first proposed in 1637 by Rene Descartes. He explained rainbows as a phenomenon related to the reflection and refraction of light in raindrops.

The formation of colors and their sequence were explained later, after unraveling the complex nature of white light and its dispersion in the medium. The diffraction theory of rainbows was developed by Erie and Partner.

We can consider the simplest case: let a beam of parallel solar rays fall on drops shaped like a ball (Fig. 10). A ray incident on the surface of a drop at point A is refracted inside it according to the law of refraction:

n sin α=n sin β, where n=1, n≈1.33 –

respectively, the refractive indices of air and water, α is the angle of incidence, and β is the angle of refraction of light.

Inside the drop, the ray AB travels in a straight line. At point B, the beam is partially refracted and partially reflected. It should be noted that the smaller the angle of incidence at point B, and therefore at point A, the lower the intensity of the reflected beam and the greater the intensity of the refracted beam.

Beam AB, after reflection at point B, occurs at an angle β`=β b and hits point C, where partial reflection and partial refraction of light also occurs. The refracted ray leaves the drop at an angle γ, and the reflected ray can travel further, to point D, etc. Thus, the light ray in the drop undergoes multiple reflection and refraction. With each reflection, some of the light rays come out and their intensity inside the drop decreases. The most intense of the rays emerging into the air is the ray emerging from the drop at point B. But it is difficult to observe it, since it is lost against the background of bright direct sunlight. The rays refracted at point C together create a primary rainbow against the background of a dark cloud, and the rays refracted at point D produce a secondary rainbow, which is less intense than the primary one.

When considering the formation of a rainbow, one more phenomenon must be taken into account - the unequal refraction of light waves of different lengths, that is, light rays of different colors. This phenomenon is called dispersion. Due to dispersion, the angles of refraction γ and the angle of deflection Θ of rays in a drop are different for rays of different colors.

Most often we see one rainbow. It is not uncommon for two rainbow stripes to appear in the sky at the same time, located one after the other; They also observe an even larger number of celestial arcs - three, four and even five at the same time. This interesting phenomenon was observed by Leningraders on September 24, 1948, when in the afternoon four rainbows appeared among the clouds over the Neva. It turns out that rainbows can arise not only from direct rays; It often appears in the reflected rays of the Sun. This can be seen on the shores of sea bays, large rivers and lakes. Three or four rainbows - ordinary and reflected - sometimes create a beautiful picture. Since the rays of the Sun reflected from the water surface go from bottom to top, the rainbow formed in the rays can sometimes look completely unusual.

You should not think that rainbows can only be seen during the day. It also happens at night, although it is always weak. You can see such a rainbow after a night rain, when the Moon appears from behind the clouds.

Some semblance of a rainbow can be obtained through the following experiment: You need to illuminate a flask filled with water with sunlight or a lamp through a hole in a white board. Then a rainbow will become clearly visible on the board, and the angle of divergence of the rays compared to the initial direction will be about 41-42°. Under natural conditions, there is no screen; the image appears on the retina of the eye, and the eye projects this image onto the clouds.

If a rainbow appears in the evening before sunset, then a red rainbow is observed. In the last five or ten minutes before sunset, all the colors of the rainbow except red disappear, and it becomes very bright and visible even ten minutes after sunset.

A rainbow on the dew is a beautiful sight. It can be observed at sunrise on the grass covered with dew. This rainbow is shaped like a hyperbola.

Auroras

One of the most beautiful optical phenomena of nature is the aurora.

In most cases, auroras have a green or blue-green hue with occasional spots or a border of pink or red.

Auroras are observed in two main forms - in the form of ribbons and in the form of cloud-like spots. When the radiance is intense, it takes the form of ribbons. Losing intensity, it turns into spots. However, many tapes disappear before they have time to break into spots. The ribbons seem to hang in the dark space of the sky, resembling a giant curtain or drapery, usually stretching from east to west for thousands of kilometers. The height of this curtain is several hundred kilometers, the thickness does not exceed several hundred meters, and it is so delicate and transparent that the stars are visible through it. The lower edge of the curtain is quite sharply and clearly outlined and is often tinted in a red or pinkish color, reminiscent of a curtain border; the upper edge is gradually lost in height and this creates a particularly impressive impression of the depth of space.

There are four types of auroras:

A homogeneous arc - a luminous stripe has the simplest, calmest shape. It is brighter from below and gradually disappears upward against the background of the sky glow;

Radiant arc - the tape becomes somewhat more active and mobile, it forms small folds and streams;

Radial stripe - with increasing activity, larger folds overlap small ones;

As activity increases, the folds or loops expand to enormous sizes, and the bottom edge of the ribbon glows brightly with a pink glow. When activity subsides, the folds disappear and the tape returns to a uniform shape. This suggests that a homogeneous structure is the main form of the aurora, and folds are associated with increasing activity.

Radiances of a different type often appear. They cover the entire polar region and are very intense. They occur during an increase in solar activity. These auroras appear as a whitish-green cap. Such auroras are called squalls.

Based on the brightness of the aurora, they are divided into four classes, differing from each other by one order of magnitude (that is, 10 times). The first class includes auroras that are barely noticeable and approximately equal in brightness to the Milky Way, while the fourth class auroras illuminate the Earth as brightly as the full Moon.

It should be noted that the resulting aurora spreads to the west at a speed of 1 km/sec. The upper layers of the atmosphere in the area of ​​auroral flashes heat up and rush upward, which affected the increased braking of artificial Earth satellites passing through these zones.

During auroras, eddy electric currents arise in the Earth's atmosphere, covering large areas. They excite magnetic storms, the so-called additional unstable magnetic fields. When the atmosphere shines, it emits X-rays, which are most likely the result of the deceleration of electrons in the atmosphere.

Frequent flashes of radiance are almost always accompanied by sounds reminiscent of noise and crackling. Auroras have a great influence on strong changes in the ionosphere, which in turn affect radio communication conditions, i.e. radio communication is greatly deteriorated, resulting in severe interference, or even complete loss of reception.

The emergence of auroras.

The Earth is a huge magnet, the north pole of which is located near the south geographic pole, and the south pole is located near the north. And the Earth's magnetic field lines are geomagnetic lines emerging from the region adjacent to the Earth's north magnetic pole. They cover the entire globe and enter it in the region of the south magnetic pole, forming a toroidal lattice around the Earth.

It was believed for a long period of time that the location of magnetic field lines was symmetrical relative to the earth's axis. But in fact, it turned out that the so-called “solar wind,” i.e., a stream of protons and electrons emitted by the Sun, attacks the geomagnetic shell of the Earth from a height of about 20,000 km. It pulls it away from the Sun, thereby forming a kind of magnetic “tail” on the Earth.

Once in the Earth's magnetic field, an electron or proton moves in a spiral, winding around the geomagnetic line. These particles, falling from the solar wind into the Earth's magnetic field, are divided into two parts: one part along the magnetic field lines immediately flows into the polar regions of the Earth, and the other gets inside the teroid and moves inside it, as can be done according to the left-hand rule, along closed curve ABC. Ultimately, these protons and electrons also flow along geomagnetic lines to the region of the poles, where their increased concentration appears. Protons and electrons produce ionization and excitation of atoms and molecules of gases. They have enough energy for this. Since protons arrive on Earth with energies of 10,000-20,000 eV (1 eV = 1.6 10 J), and electrons with energies of 10-20 eV. But for the ionization of atoms it is necessary: ​​for hydrogen - 13.56 eV, for oxygen - 13.56 eV, for nitrogen - 124.47 eV, and even less for excitation.

Based on the principle that occurs in tubes with rarefied gas when currents are passed through them, excited gas atoms give back the received energy in the form of light.

The green and red glow, according to the results of a spectral study, belongs to excited oxygen atoms, and the infrared and violet glow belongs to ionized nitrogen molecules. Some oxygen and nitrogen emission lines form at an altitude of 110 km, and the red glow of oxygen occurs at an altitude of 200-400 km. The next weak source of red light is hydrogen atoms, formed in the upper layers of the atmosphere from protons arriving from the Sun. Such a proton, after capturing an electron, turns into an excited hydrogen atom and emits red light.

After solar flares, auroral flares usually occur within a day or two. This indicates a connection between these phenomena. Research using rockets has shown that in places of greater intensity of auroras, a higher level of ionization of gases by electrons remains. According to scientists, the maximum intensity of auroras is achieved off the coast of oceans and seas.

There are a number of difficulties for the scientific explanation of all phenomena associated with auroras. That is, the mechanism for accelerating particles to certain energies is not completely known, their trajectories of motion in near-Earth space are not clear, the mechanism for the formation of various types of luminescence is not entirely clear, the origin of sounds is unclear, and not everything agrees quantitatively in the energy balance of ionization and excitation of particles.

Used Books:

1. “Physics in Nature”, author - L. V. Tarasov, Prosveshchenie Publishing House, Moscow, 1988.
2. “Optical phenomena in nature”, author - V. L. Bulat, publishing house “Prosveshchenie”, Moscow, 1974.
3. “Conversations on Physics, Part II”, author - M.I. Bludov, Prosveshchenie Publishing House, Moscow, 1985.
4. “Physics 10”, authors - G. Ya. Myakishev B. B. Bukhovtsev, Prosveshchenie publishing house, Moscow, 1987.
5. “Encyclopedic Dictionary of a Young Physicist”, compiled by V. A. Chuyanov, Pedagogika Publishing House, Moscow, 1984.
6. “Schoolchildren's Handbook on Physics”, compiled by, philological society “Slovo”, Moscow, 1995.
7. “Physics 11”, N. M. Shakhmaev, S. N. Shakhmaev, D. Sh. Shodiev, Prosveshchenie publishing house, Moscow, 1991.
8. “Solving problems in physics”, V. A. Shevtsov, Nizhne-Volzhskoe book publishing house, Volgograd, 1999.

A person constantly encounters light phenomena. Everything that is associated with the emergence of light, its propagation and interaction with matter is called light phenomena. Vivid examples of optical phenomena can be: a rainbow after rain, lightning during a thunderstorm, the twinkling of stars in the night sky, the play of light in a stream of water, the variability of the ocean and sky, and many others.

Students receive scientific explanations of physical phenomena and optical examples in 7th grade when they begin to study physics. For many, optics will become the most fascinating and mysterious section in the school physics curriculum.

What does a person see?

Human eyes are designed in such a way that he can only perceive the colors of the rainbow. Today it is already known that the spectrum of the rainbow is not limited to red on one side and violet on the other. After red comes infrared, after violet comes ultraviolet. Many animals and insects are able to see these colors, but people, unfortunately, cannot. But a person can create devices that receive and emit light waves of the appropriate length.

Refraction of rays

Visible light is a rainbow of colors, and white light, such as sunlight, is a simple combination of these colors. If you place a prism in a beam of bright white light, it will break down into the colors or wavelengths of which it is composed. First, red with a longer wavelength will appear, then orange, yellow, green, blue and finally violet, which has the shortest wavelength in visible light.

If you take another prism to catch the light of the rainbow and turn it upside down, it will merge all the colors into white. There are many examples of optical phenomena in physics; let’s consider some of them.

Why the sky is blue?

Young parents are often perplexed by the simplest, at first glance, questions of their little whys. Sometimes they are the hardest to answer. Almost all examples of optical phenomena in nature can be explained by modern science.

The sunlight that illuminates the sky during the day is white, which means that, in theory, the sky should also be bright white. In order for it to look blue, some processes are necessary with the light as it passes through the Earth's atmosphere. Here's what happens: Some of the light passes through the free space between gas molecules in the atmosphere, reaching the earth's surface and remaining the same white color as when it started. But sunlight encounters gas molecules, which, like oxygen, are absorbed and then scattered in all directions.

The atoms in the gas molecules are activated by the light they absorb and again emit photons of light in wavelengths ranging from red to violet. Thus, some of the light is directed towards the earth, the rest is sent back to the Sun. The brightness of the emitted light depends on the color. Eight photons of blue light are released for every photon of red light. Therefore, blue light is eight times brighter than red. Intense blue light is emitted from all directions from billions of gas molecules and reaches our eyes.

Multicolored arch

Once upon a time, people thought that rainbows were signs sent to them by the gods. Indeed, beautiful multi-colored ribbons always appear in the sky out of nowhere, and then just as mysteriously disappear. Today we know that a rainbow is one of the examples of optical phenomena in physics, but we never cease to admire it every time we see it in the sky. The interesting thing is that each observer sees a different rainbow, created by the rays of light coming from behind him and from the raindrops in front of him.

What are rainbows made of?

The recipe for these optical phenomena in nature is simple: water droplets in the air, light and an observer. But it is not enough for the sun to appear when it rains. It should be low, and the observer should stand so that the sun is behind him, and look at the place where it is raining or has just rained.

A sunbeam coming from distant space catches a raindrop. Acting like a prism, a raindrop refracts every color hidden in the white light. Thus, when a white ray passes through a raindrop, it suddenly splits into beautiful multi-colored rays. Inside the drop, they encounter its inner wall, which acts like a mirror, and the rays are reflected in the same direction from which they entered the drop.

The end result is that the eyes see a rainbow of colors arching across the sky - light bent and reflected by millions of tiny raindrops. They can act like small prisms, splitting white light into a spectrum of colors. But rain is not always necessary to see a rainbow. Light can also be refracted by fog or sea vapors.

What color is the water?

The answer is obvious - the water is blue. If you pour clean water into a glass, everyone will see its transparency. This is because there is too little water in the glass and the color is too pale to see.

When filling a large glass container, you can see the natural blue tint of the water. Its color depends on how the water molecules absorb or reflect light. White light is made up of a rainbow of colors, and water molecules absorb most of the colors of the red to green spectrum that pass through them. And the blue part is reflected back. So we see the color blue.

Sunrises and sunsets

These are also examples of optical phenomena that humans observe every day. When the sun rises and sets, it directs its rays at an angle to the place where the observer is located. They have a longer path than when the sun is at its zenith.

Layers of air above the Earth's surface often contain a lot of dust or microscopic moisture particles. The sun's rays pass at an angle to the surface and are filtered. Red rays have the longest wavelength of radiation and therefore penetrate more easily to the ground than blue rays, which have short waves that are reflected by particles of dust and water. Therefore, during the morning and evening dawn, a person observes only part of the sun's rays that reach the earth, namely red ones.

Planet light show

A typical aurora is a colorful display of light in the night sky that can be seen every night at the North Pole. Changing in bizarre shapes, huge bands of blue-green light with orange and red spots sometimes reach more than 160 km in width and can extend 1,600 km in length.

How to explain this optical phenomenon, which is such a breathtaking spectacle? Auroras appear on Earth, but they are caused by processes occurring on the distant Sun.

How is everything going?

The Sun is a huge ball of gas consisting mainly of hydrogen and helium atoms. They all have protons with a positive charge and electrons with a negative charge orbiting around them. A constant halo of hot gas spreads into space in the form of solar wind. This countless number of protons and electrons rushes at a speed of 1000 km per second.

When solar wind particles reach Earth, they are attracted by the planet's strong magnetic field. The Earth is a giant magnet with magnetic lines that converge at the North and South Poles. The attracted particles flow along these invisible lines near the poles and collide with the nitrogen and oxygen atoms that make up the Earth's atmosphere.

Some of the earth's atoms lose their electrons, others are charged with new energy. After colliding with protons and electrons from the Sun, they release photons of light. For example, nitrogen that has lost electrons attracts violet and blue light, while charged nitrogen glows dark red. Charged oxygen gives off green and red light. Thus, charged particles cause the air to shimmer in many colors. This is the aurora.

Mirages

It should be immediately determined that mirages are not a figment of human imagination, they can even be photographed, they are almost mystical examples of optical physical phenomena.

There is a lot of evidence of the observation of mirages, but science can provide a scientific explanation for this miracle. They can be as simple as a patch of water among the hot sands, or they can be stunningly complex, constructing visions of pillared hanging castles or frigates. All of these examples of optical phenomena are created by the play of light and air.

Light waves bend when they pass through first warm and then cold air. Hot air is more rarefied than cold air, so its molecules are more active and disperse over longer distances. As the temperature decreases, the movement of molecules also decreases.

Visions seen through the lenses of the earth's atmosphere may be greatly altered, compressed, expanded, or inverted. This is because light rays bend as they pass through warm and then cold air, and vice versa. And those images that the light stream carries with it, for example the sky, can be reflected on the hot sand and seem like a piece of water, which always moves away when approaching.

Most often, mirages can be observed at long distances: in deserts, seas and oceans, where there can be hot and cold layers of air with different densities at the same time. It is the passage through different temperature layers that can twist the light wave and ultimately result in a vision that is a reflection of something and is presented by fantasy as a real phenomenon.

Halo

For most optical illusions that can be observed with the naked eye, the explanation is the refraction of sunlight in the atmosphere. One of the most unusual examples of optical phenomena is the solar halo. Essentially, a halo is a rainbow around the sun. However, it differs from an ordinary rainbow both in appearance and in its properties.

This phenomenon has many varieties, each of which is beautiful in its own way. But for any type of optical illusion to occur, certain conditions are necessary.

A halo appears in the sky when several factors coincide. Most often it can be seen in frosty weather with high humidity. There are a large number of ice crystals in the air. Making its way through them, sunlight is refracted in such a way that it forms an arc around the Sun.

And although the last 3 examples of optical phenomena are easily explained by modern science, for the ordinary observer they often remain mystical and a mystery.

Having examined the main examples of optical phenomena, we can confidently believe that many of them can be explained by modern science, despite their mysticism and mystery. But scientists still have a lot of discoveries ahead, clues to the mysterious phenomena that occur on planet Earth and beyond.