Optical phenomena in the atmosphere. Electrical and optical phenomena in the atmosphere

Abstract of a geography lesson

"Optical phenomena in the atmosphere"

Grade 6, GEF

Prepared

geography teacher

MOBU Molchanovskaya secondary school

Gorkavaya Galina Sergeevna

Lesson summary on the topic: "Optical phenomena in the atmosphere"

	FULL NAME	Gorkavaya Galina Sergeevna
	Place of work	MOBU Molchanovskaya secondary school
	Position	geography teacher
	Thing	geography
	Class
	Topic and lesson number in the topic	Optical phenomena in the atmosphere. (in section VI "Atmosphere-air shell of the Earth »
	Basic Tutorial	Geography Planet earth. Grade 5-6. Textbook (A. A. Lobzhanidze)

The purpose of the lesson : To form an idea of the mutual influence of the atmosphere and man, natural atmospheric phenomena;

9. Tasks:

- educational : Gain knowledge about optical phenomena in the atmosphere

- developing : development of cognitive interests of students, the ability to work in a group with a textbook, additional literature and EER resources.,

- educational : the formation of a culture of communication when working in a group

Planned results:

Personal : awareness of the values of geographical knowledge, as essential component scientific picture of the world.

Metasubject : the ability to organize one's activities, determine its goals and objectives, the ability to conduct an independent search, analysis, selection of information, the ability to interact with people and work in a team. Express judgments, confirming them with facts. mastering elementary practical skills of working with a textbook for research,

subject : Distinguish between atmospheric phenomena associated with the reflection of sunlight, electricity, dangerous phenomena associated with precipitation, with winds. Name the types of air pollution resulting from economic activity human

Universal learning activities:

Personal: realize the need to study the world around.

Regulatory: plan their activities under the guidance of a teacher, evaluate the work of classmates, work in accordance with the task, compare the results with the expected ones.

Cognitive: extract information about optical phenomena in the atmosphere, natural hazards in the atmosphere, the role air shell Earth in the life and economic activity of a person to extract new knowledge from the sources of ESM, process information to obtain desired result.

Communicative: the ability to communicate and interact with each other.

Lesson type: combined

Student work form: collective, work in pairs

Technical equipment : multimedia installation, interactive whiteboard, Internet, ESM, Personal Computer.

During the classes.

Teacher: Hello guys! You came here to study, not to be lazy, but to work. I wish you all a good mood! Sit down.

Let's remember what section we are studying? Solve the riddle!

Are there children, a blanket,
To cover the whole Earth?
To have enough for everyone
Was it not visible?
Don't fold, don't unfold
Do not feel, do not look?
Let rain and light through
Is there, but is it not?
- What is this blanket? children answer(atmosphere)

Teacher: Right.

The atmosphere is not homogeneous, does it have several layers? (Troposphere, stratosphere and upper atmosphere)

What is the earth's atmosphere made of? (A mixture of gases, tiny drops of water and ice crystals, dust, soot, organic matter.)

What is the gas composition of the atmosphere? (nitrogen - 78%; oxygen 21%; argon - 0.9% and other gases 0.1%)

Now, with a little knowledge, you can explain most of the phenomena that occur in the atmosphere. But in ancient times, people did not have the opportunity to do this, so atmospheric phenomena frightened superstitious people, they were considered harbingers of disasters and misfortunes.

And what is this mysterious vessel on my table? You do not know? Let's get a look?

Music. (He opens the vessel, smoke pours out of it, old Hottabych appears.)

Hottabych: Apchi! Greetings, my wise lord! (Dalley wordsHottabycha, played by one of the students are underlined.)
- Where are you from? Are you from the theatre?
– Oh no, my lord! I'm from this vessel!
- So you..?
– Yes, I am the mighty and glorified genie in all four countries of the world Hassan Abdurahman ibn Hottab, that is, the son of Hottab!
- Hottabych?!
– And who are these beautiful youths?
- And these are students of the 6th grade, and now we have a geography lesson.
– Geography lesson! Know, O most beautiful of the beautiful, that you are unheard of lucky, for I am rich in knowledge of geography. I will teach you, and you will become famous among the students of your school.

- We are very happy about this, dear Hottabych.
– And what is this magical black box that lies on the table?
- This is a computer with the help of which modern children receive useful information and which will help us today in the lesson. I invite you, dear Hottabych, to work with us today.

Hottabych: Thank you! I agree with great pleasure! (Sits down at the desk)

Today we will get acquainted with some optical phenomena, fill in the table that lies in front of you. Well, our esteemed Hottabych will tell us how the ancients represented this or that phenomenon.

So let's get started!

Exploring a new topic.

Open your workbooks, write down the number and Leave space to record a topic; below, while watching the videos that I will show you, please write down the names of those atmospheric phenomena who are so frightened before people, exactly in the order in which you will view them (as a rule, students can easily identify a rainbow, aurora, lightning, but there are difficulties with the definition of a halo and a mirage

1.Rainbow -

2. Mirage

3. Halo -

4. Aurora -

5. Lightning -

6. Fires of St. Elmo

Let's compare what you got? Slides 1-7

7 slide- All these phenomena are called optical phenomena in the atmosphere.

8 slideWrite the title of the topic in your notebook.

Slide 9 (goals and objectives) Say the goal!

Slide 10

Textbook work. Your task is to enter the causes of optical phenomena on the card!

Work with the textbook p.118 (phenomena associated with the reflection of sunlight: rainbow, mirage, halo)

Work with the textbook p.119 (electrical phenomena: aurora, lightning, St. Elmo's Fire)

Time - min.

Teacher: So, are you ready? Our esteemed Hottabych will tell us how the ancients represented this or that phenomenon. And a speaker from each group will talk about the causes of phenomena! (Come out to the board)

The first phenomenon you identified is rainbow. The first word is given to you Hottabych!

Hottabych:It was believed that the rainbow was created by God ancient Babylon as a sign that he decided to stop the Flood.

Teacher: Let's find out the cause of the rainbow!

Speaker: Sunlight appears white to us, but it is actually made up of 7 colors of light: red, orange, green, blue, indigo and violet. Passing through the drops of water, the sun's ray is refracted and breaks up into different colors. That's why after the rain or near the waterfalls you can see the rainbow.

– Many desert travelers witness another atmospheric phenomenon – Mirage.

Hottabych:The ancient Egyptians believed that a mirage is the ghost of a country that no longer exists.

- Why do mirages occur?

Speaker:This happens when hot air above the surface rises. Its density begins to increase. Air at different temperatures has different densities, and a beam of light, passing from layer to layer, will bend, visually bringing the object closer. M. arise over a hot (desert, asphalt), or, on the contrary, over a chilled surface (water)

In frosty weather, pronounced rings appear around the Sun and Moon - Halo.

Hottabych:It used to be thought that a witches' sabbath took place at this time.

Speaker: They occur when light is reflected in the ice crystals of cirrostratus clouds. Crowns - several rings suddenly nested into each other.

- Thank you. (speaker leaves, Hottabych remains)

And now who wants to talk about the phenomena associated with electricity? invite a speaker from the next group).

(Speaker exits)

- Residents of the polar regions can admire the Northern Lights.

Hottabych:Indians North America believed that these were the fires of sorcerers, on which they boiled their captives in cauldrons.

Speaker: The sun sends a stream of electrically charged particles to the Earth, which collide with air particles and begin to glow.

- Lightning -"A fire arrow is flying, no one will catch it - neither the king, nor the queen, nor the fair maiden.

Hottabych:It was believed thatit is God Perun who strikes a snake with his stone weapon.

Speaker:Visible electrical discharge between the clouds, or between the cloud and the earth. Lightning Thunder.

And what are the types of lightning (linear and ball), what are the dangers?

- And the last phenomenon is the "Fires of St. Elmo."

Hottabych:"St. Elmo's Lights"sailors considered him a bad sign.

Where can such a phenomenon be observed?

Speaker: This illumination can be observed in thundery weather on the high spiers of the towers, as well as around the ship's masts.

- Thank you Hottabych, thanks to you the guys learned about the views of the ancients on optical phenomena.

Hottabych:And thank you for inviting me to participate in your lesson.!

PHYSMINUTE.

Consolidation of the material covered:

Work in pairs! Solve the crossword

Students complete the crossword puzzle. Who got what?

Lesson summary: (reflection )

What new did you learn at the lesson today? Have you observed any phenomenon?

Guys, look at the blackboard. The sun is completely without rays! Everyone has 3 rays on the desk, evaluate your work (choosing one for yourself) and attach it to the sun.

Well done! Today you did a good job, this topic is very complex, and you will study it more deeply in the course of physics.

Guys, tell me, what rating would you give to our guest Hottabych? (Five!!!) I agree with you completely! Other student grades.

slide 11 Now write down homework. Paragraph 46 repeat, answer the questions.

Thanks everyone for the lesson!

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

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Ministry of Education and Science of the Russian Federation

Federal State Budgetary educational institution higher professional education.

"Kazan National Research Technological University"

On the topic: Optical phenomena in the atmosphere

Completed the work: Zinnatov Rustam Ramilovich

Checked: Salmanov Robert Salikhovich

1. Phenomena associated with the refraction of light

2. Phenomena associated with the dispersion of light

3. Phenomena associated with the interference of light

Conclusion

1. phenomena, related to the refraction of light

In an inhomogeneous medium, light does not propagate in a straight line. If we imagine a medium in which the refractive index changes from bottom to top, and mentally divide it into thin horizontal layers, then, considering the conditions for refraction of light during the transition from layer to layer, we note that in such a medium the light beam should gradually change its direction.

Such a curvature of the light beam undergoes in the atmosphere, in which, for one reason or another, mainly due to its uneven heating, the refractive index of the air changes with height.

The air is usually heated by the soil, which absorbs the energy of the sun's rays. Therefore, the air temperature decreases with altitude. It is also known that air density decreases with height. It has been established that with increasing altitude, the refractive index decreases, so the rays passing through the atmosphere are bent, bending down to the Earth. This phenomenon is called normal atmospheric refraction. Due to refraction, the celestial bodies seem to us somewhat "raised" (above their true height) above the horizon.

Mirages are divided into three classes.

The first class includes the most common and simple in origin, the so-called lake (or lower) mirages, which cause so many hopes and disappointments among desert travelers.

The explanation for this phenomenon is simple. The lower layers of air, warmed up by the soil, have not had time to rise up; their refractive index is less than the upper ones. Therefore, the rays of light emanating from objects, bending in the air, enter the eye from below.

To see a mirage, there is no need to go to Africa. It can be observed on a hot, quiet summer day and over the heated surface of an asphalt highway.

Mirages of the second class are called superior or distant vision mirages.

They appear in the event that the upper layers of the atmosphere turn out to be for some reason, for example, when heated air gets there, especially rarefied. Then the rays emanating from earthly objects are more strongly bent and reach earth's surface going at a high angle to the horizon. The observer's eye projects them in the direction in which they enter it.

Apparently, the Sahara Desert is to blame for the fact that a large number of long-range mirages are observed on the Mediterranean coast. Hot air masses rise above it, then are carried away to the north and create favorable conditions for the appearance of mirages.

Superior mirages are also observed in northern countries when the warm south winds blow. The upper layers of the atmosphere are heated, and the lower ones are cooled due to the presence of large masses melting ice and snow.

Mirages of the third class - ultra-long vision - are difficult to explain. However, assumptions were made about the formation of giant air lenses in the atmosphere, about the creation of a secondary mirage, that is, a mirage from a mirage. It is possible that the ionosphere plays a role here, reflecting not only radio waves, but also light waves.

2. Phenomena related to the dispersion of light

rainbow is beautiful celestial phenomenon- has always attracted people's attention. AT old times, when people still knew very little about the world around them, the rainbow was considered a "heavenly sign." So, the ancient Greeks thought that a hundred rainbow is the smile of the goddess Irida. The rainbow is observed in the direction opposite to the Sun, against the background of rain clouds or rain. A multi-colored arc is usually located at a distance of 1-2 km from the observer Ra, sometimes it can be observed at a distance of 2-3 m against the background of water drops formed by fountains or water sprayers

The rainbow has seven primary colors that smoothly transition from one to another.

The shape of the arc, the brightness of the colors, 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 an arc that is blurry, faded and even white. 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 given in 1637 by R. Descartes. He explained the rainbow as a phenomenon associated with 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 a medium. The diffraction theory of the rainbow was developed by Airy and Pertner.

3. Light Interference Phenomena

The white circles of light around the Sun or Moon, which result from the refraction or reflection of light by ice or snow crystals in the atmosphere, are called halos. There are small water crystals in the atmosphere, and when their faces form a right angle with the plane passing through the Sun, the one who observes the effect, and the crystals, a characteristic white halo surrounding the Sun becomes visible in the sky. So the edges reflect the rays of light with a deviation of 22 °, forming a halo. During the cold season, halos formed by ice and snow crystals on the earth's surface reflect sunlight and scatter it in different directions, forming an effect called "diamond dust".

The most famous example of a large halo is the famous, oft-repeated "Brocken Vision". For example, a person standing on a hill or mountain, behind whom the sun rises or sets, finds that his shadow, which has fallen on the clouds, becomes unbelievably huge. This is due to the fact that the smallest drops of fog refract and reflect sunlight in a special way. The phenomenon got its name from the Brocken peak in Germany, where, due to frequent fogs, this effect can be regularly observed.

Parhelia.

"Parhelion" in Greek means "false sun". This is one of the halo forms (see point 6): one or more additional images of the Sun are observed in the sky, located at the same height above the horizon as the real Sun. Millions of ice crystals with a vertical surface, reflecting the Sun, form this most beautiful phenomenon.

Parhelia can be observed in calm weather at a low position of the Sun, when a significant number of prisms are located in the air so that their main axes are vertical, and the prisms slowly descend like small parachutes. In this case, the brightest refracted light enters the eye at an angle of 220 from the vertical faces and creates vertical pillars on both sides of the Sun along the horizon. These pillars can be particularly bright in some places, giving the impression of a false Sun.

Polar Lights.

One of the most beautiful optical phenomena of nature is the aurora borealis. It is impossible to convey in words the beauty of the auroras, shimmering, shimmering, flaming against the dark night sky in the polar latitudes.

In most cases, auroras are green or blue-green in color, with occasional patches or borders of pink or red. refraction dispersion interference light

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 on the form of ribbons. Losing intensity, it turns into spots. However, many ribbons disappear before they 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 the curtain is several hundred kilometers, the thickness does not exceed several hundred meters, and it is so delicate and transparent that stars can be seen through it. The lower edge of the curtain is quite distinctly and sharply outlined and often tinted in red or pinkish color, reminiscent of the border of the curtain, the upper one is gradually lost in height and this creates a particularly effective impression of the depth of space.

There are four types of auroras:

1. Uniform arc - the luminous strip has the most simple, calm form. It is brighter from below and gradually disappears upward against the background of the glow of the sky;

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

3. Radiant band - with increasing activity, larger folds are superimposed on small ones;

4. With an increase in activity, the folds or loops expand to enormous sizes (up to hundreds of kilometers), the lower edge of the tape shines with pink light. When the activity subsides, the wrinkles disappear and the tape returns to a uniform shape. This suggests that homogeneous structure are the main form of the aurora, and the folds are associated with an increase in activity.

Often there are aurora of a different kind. They capture the entire polar region and are very intense. They occur during an increase in solar activity. These auroras appear as a whitish-green glow from the entire polar cap. Such auroras are called squalls.

Conclusion

Once the mirages "Flying Dutchman" and "Fata Morgana" terrified sailors. On the night of March 27, 1898, among Pacific Ocean the crew of the Matador was frightened by a vision when, in a calm at midnight, they saw a ship 2 miles (3.2 km) away, which was struggling with a severe storm. All these events actually took place at a distance of 1700 km.

Today, everyone who knows the laws of physics, or rather its section of optics, can explain all these mysterious phenomena.

In my work, I did not describe all the optical phenomena of nature. There are a lot of them. We admire blue color sky, a ruddy dawn, a flaming sunset - these phenomena are explained by the absorption and scattering of sunlight. Working with additional literature, I was convinced that the questions that arise when observing the world around us can always be answered. True, one must know the basics of the natural sciences.

CONCLUSION: Optical phenomena in nature are explained by the refraction or reflection of light, or wave properties light-dispersion, interference, diffraction, polarization, or quantum properties of light. The world is mysterious, but knowable

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What does the 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 purple on the other. Red is followed by infrared, and violet is followed by ultraviolet. Many animals and insects are able to see these colors, but unfortunately humans cannot. But on the other hand, 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 up into colors or waves. different lengths, of which it consists. First comes red with the longest wavelength, 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 combine 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 most simple, at first glance, questions of their little why. 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, theoretically, the sky should also be bright white. In order for it to look blue, some processes with light are necessary at the time of its passage through the Earth's atmosphere. Here's what happens: some of the light passes through the free space between the gas molecules in the atmosphere, reaching the earth's surface and remaining the same white color as at the beginning of the journey. But sunlight hits gas molecules, which, like oxygen, are absorbed and then scattered in all directions.

The atoms in the gas molecules are activated by the absorbed light and again emit photons of light in waves various lengths- from red to purple. Thus, some of the light goes to the earth, the rest goes 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. 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.

colorful 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 from nowhere, and then just as mysteriously disappear. Today we know that the rainbow is one of the examples of optical phenomena in physics, but we do not 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 rays of light coming from behind him and from 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 during the rain. 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 just rained.

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

The end result is 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 fumes from the sea.

What color is the water?

The answer is obvious - water has a blue color. 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 its color is too pale to see it.

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

Sunrises and sunsets

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

The 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 make their way to the ground more easily than blue rays, which have short waves that are beaten off by particles of dust and water. Therefore, during the morning and evening dawn, a person observes only a part of the sun's rays that reach the earth, namely red ones.

planet light show

A typical aurora is a multi-colored aurora in the night sky that can be observed every night at the North Pole. Shifting in bizarre shapes, huge streaks of blue-green light with orange and red spots sometimes reach more than 160 km in width and can stretch for 1600 km in length.

How to explain this optical phenomenon, which is such a breathtaking sight? 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 revolving around them. A halo of hot gas constantly spreads into space in the form solar wind. This countless number of protons and electrons are rushing at a speed of 1000 km per second.

When solar wind particles reach the 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 the protons and electrons of the Sun, they give off photons of light. For example, nitrogen that has lost electrons attracts violet and blue light, while charged nitrogen shines dark red. Charged oxygen gives off green and red light. Thus, the charged particles cause the air to shimmer with many colors. This is the aurora borealis.

Mirages

It should immediately be 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 give a scientific explanation for this miracle. They can be as simple as a patch of water amid hot sands, or they can be stunningly complex, constructing visions of pillared castles or frigates. All these examples of optical phenomena are created by the play of light and air.

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

Visions seen through the lenses of the earth's atmosphere can be highly 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 a light stream carries with it, for example, the sky, can be reflected on hot sand and seem like a piece of water, which always moves away when approached.

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

Halo

For most optical illusions that can be seen with the naked eye, the explanation is the refraction of the sun's rays in the atmosphere. One of the most unusual examples of optical phenomena is solar halo. Basically, a halo is a rainbow around the sun. However, it differs from the usual rainbow both in appearance and in its properties.

This phenomenon has many varieties, each of which is beautiful in its own way. But for the occurrence of any kind of this optical illusion certain conditions are required.

A halo occurs in the sky when several factors coincide. Most often it can be seen in frosty weather with high humidity. At the same time, there are a large number of ice crystals in the air. Breaking through them, the 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 an ordinary observer they often remain mystic and a mystery.

Having considered the main examples of optical phenomena, it can be safely assumed that many of them are explained by modern science, despite their mysticism and mystery. But ahead of scientists there are still a lot of discoveries, clues to the mysterious phenomena that occur on planet Earth and beyond.

Lyceum Petru Movila

Course work in physics on the topic:

Optical atmospheric phenomena

The work of a student of grade 11A

Bolyubash Irina

Chisinau 2006 -

Plan:

1. Introduction

a) What is optics?

b) Types of optics

2. Earth's atmosphere as an optical system

3. sunny sunset

a) sky color change

b) Sun rays

in) The uniqueness of sunsets

4. Rainbow

a) rainbow formation

b) Variety of rainbows

5. auroras

a) Types of auroras

b) Solar wind as the cause of auroras

6. Halo

a) light and ice

b) Prism crystals

7. Mirage

a) Explanation of the lower ("lake") mirage

b) superior mirages

in) Double and triple mirages

G) Mirage of ultra-long vision

e) Legend of the Alps

e) Parade of superstitions

8. Some mysteries of optical phenomena

Introduction

What is optics?

The first ideas of ancient scientists about light were very naive. It was believed that special thin tentacles come out of the eyes and visual impressions arise when they feel objects. At that time, optics was understood as the science of vision. This is the exact meaning of the word "optics". In the Middle Ages, optics gradually turned from the science of vision into the science of light. This was facilitated by the invention of lenses and the camera obscura. In modern times, optics is a branch of physics that studies the emission of light, its propagation in various media and interaction with matter. As for issues related to vision, the structure and functioning of the eye, they stood out in a special scientific direction called physiological optics.

The concept of "optics", in modern science, has a multifaceted meaning. These are atmospheric optics, and molecular optics, and electron optics, and neutron optics, and nonlinear optics, and holography, and radio optics, and picosecond optics, and adaptive optics, and many other phenomena and scientific research methods closely related to optical phenomena.

Most of the listed species optics, like physical phenomenon, are available to our observation only when using special technical devices. It can be laser systems, X-ray emitters, radio telescopes, plasma generators and many more. But the most accessible and, at the same time, the most colorful optical phenomena are atmospheric. Huge in scale, they are the product of the interaction of light and the atmosphere of the earth.

Earth's atmosphere as an optical system

Our planet is surrounded by a gaseous shell, which we call the atmosphere. Possessing highest density near the earth's surface and gradually rarefied as it rises, it reaches a thickness of more than a hundred kilometers. And this is not a frozen gas medium with homogeneous physical data. On the contrary, the earth's atmosphere is in constant motion. Under the influence of various factors, its layers mix, change density, temperature, transparency, move long distances at different speeds.

For rays of light coming from the sun or other heavenly bodies, the earth's atmosphere is a kind of optical system with constantly changing settings. Being in their way, it reflects part of the light, scatters it, passes it through the entire thickness of the atmosphere, providing illumination of the earth's surface, under certain conditions, decomposes it into components and bends the path of the rays, thereby causing various atmospheric phenomena. The most unusual colorful ones are sunset, rainbow, northern lights, mirage, solar and lunar halo.

sunny sunset

The simplest and most accessible atmospheric phenomenon for observation is the sunset of our celestial body - the Sun. Extraordinarily colorful, it never repeats itself. And the picture of the sky and its change in the process of sunset is so bright that it arouses admiration in every person.

Approaching the horizon, the Sun not only loses its brightness, but also begins to gradually change its color - in its spectrum, the short-wave part (red colors) is increasingly suppressed. At the same time, the sky begins to color. In the vicinity of the Sun, it acquires yellowish and orange tones, and a pale stripe with a weakly expressed gamut of colors appears above the antisolar part of the horizon.

By the time of sunset, which has already taken on a dark red color, a bright band of dawn stretches along the solar horizon, the color of which changes from bottom to top from orange-yellow to greenish-blue. A round, bright, almost uncolored radiance spreads over it. At the same time, at the opposite horizon, a bluish-gray dim segment of the Earth's shadow begins to slowly rise, bordered by a pink belt. ("Girdle of Venus").

As the Sun sinks deeper below the horizon, a rapidly spreading pink spot appears - the so-called "purple light" reaching greatest development at a depth of the Sun under the horizon of about 4-5o. Clouds and mountain peaks fill with scarlet and purple tones, and if clouds or high mountains are below the horizon, then their shadows stretch near the sunny side of the sky and become more saturated. Near the horizon, the sky turns red, and across the brightly colored sky, light rays stretch from horizon to horizon in the form of distinct radial stripes. ("Rays of the Buddha"). Meanwhile, the shadow of the Earth is rapidly moving into the sky, its outlines becoming blurry, and the pink border is barely noticeable.

Gradually, the purple light fades, the clouds darken, their silhouettes stand out distinctly against the background of the fading sky, and only at the horizon, where the Sun has hidden, is a bright multi-colored segment of dawn preserved. But it also gradually shrinks and turns pale, and by the beginning of astronomical twilight turns into a greenish-whitish narrow strip. Finally, she disappears - the night comes.

The described picture should be considered only as typical for clear weather. In fact, the nature of the sunset flow is subject to wide variations. With increased air turbidity, the colors of dawn are usually faded, especially near the horizon, where instead of red and orange tones, sometimes only a faint brown color appears. Quite often, simultaneous glow phenomena develop differently in different parts of the sky. Each sunset has a unique personality and this should be considered one of their most characteristic features.

The extreme individuality of the sunset flow and the variety of optical phenomena accompanying it depend on various optical characteristics of the atmosphere - primarily its attenuation and scattering coefficients, which manifest themselves differently depending on the zenith distance of the Sun, the direction of observation and the height of the observer.

Rainbow

The rainbow is a beautiful celestial phenomenon that has always attracted the attention of man. In the old days, 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 is the smile of the goddess Irida.

The rainbow is observed in the direction opposite to the Sun, against the background of rain clouds or rain. A 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 on the continuation of the straight line connecting the Sun and the eye of the observer - on the anti-solar line. The angle between the direction to the main rainbow and the anti-solar line is 41º - 42º

At the time of sunrise, the antisolar point is on the horizon line, and the rainbow looks like a semicircle. As the sun rises, the antisolar point falls below the horizon and the size of the rainbow decreases. It is only part of a circle.

Often there is a secondary rainbow, concentric with the first, with an angular radius of about 52º and an inverse arrangement of colors.

The main rainbow is formed by the reflection of light in water droplets. A secondary rainbow is formed as a result of a double reflection of light inside each drop. In this case, the rays of light exit the drop at different angles than those that produce the main rainbow, and the colors in the secondary rainbow are in reverse order.

The path of rays in a drop of water: a - with one reflection, b - with two reflections

At a Sun height of 41º, the main rainbow ceases to be visible and only a part of the secondary rainbow appears above the horizon, and at a Sun height of more than 52º, the secondary rainbow is not visible either. Therefore, in the middle equatorial latitudes, this natural phenomenon is never observed during the near noon hours.

The rainbow has seven primary colors that smoothly transition from one to another. The shape of the arc, the brightness of the colors, 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 an arc that is blurry, faded and even white. 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 given in 1637 by René Descartes. He explained the rainbow as a phenomenon associated with 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 a medium.

rainbow formation

Can be considered simplest case: let a beam of parallel sunlight fall on drops having the shape of a ball. A beam 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 are the refractive indices of air and water, respectively, α is the angle of incidence, and β is the angle of light refraction.

Inside the drop, the ray AB goes 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 hence 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 and hits point C, where partial reflection and partial refraction of light also occur. The refracted beam leaves the drop at an angle γ, and the reflected one can go further, to point D, etc. Thus, the light beam in the drop undergoes multiple reflections and refractions. With each reflection, some of the rays of light come out and their intensity inside the drop decreases. The most intense of the rays emerging into the air is the ray that emerged 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 rays refracted at point D give 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 different color. This phenomenon is called dispersion. Due to dispersion, the angles of refraction γ and the angle of deflection of rays in a drop are different for rays of different colors.

A rainbow is caused by the dispersion of sunlight in water droplets. In each droplet, the beam experiences multiple internal reflections, but with each reflection, part of the energy goes out. Therefore, the more internal reflections experienced by the rays in the drop, the weaker the rainbow. You can observe a rainbow if the Sun is behind the observer. Therefore, the brightest, primary rainbow is formed from rays that have experienced one internal reflection. They cross the incident rays at an angle of about 42°. The locus of points located at an angle of 42° to the incident beam is a cone, perceived by the eye at its top as a circle. When illuminated with white light, a colored band will be obtained, with the red arc always higher than the violet one.

Most often we see one rainbow. It is not uncommon for two rainbow stripes to appear simultaneously in the sky, located one after the other; an even greater number of celestial arcs are observed - three, four and even five at the same time. It turns out that a rainbow can arise not only from direct rays; often it appears in the reflected rays of the sun. This can be seen on the coast 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 a rainbow can be observed only during the day. It happens at night, however, always weak. You can see such a rainbow after a night rain, when the moon looks out from behind the clouds.

Some semblance of a rainbow can be obtained on such experience : It is necessary to illuminate a flask filled with water with sunlight or a lamp through a hole in a white board. Then a rainbow will be 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 colors of the rainbow, except for red, disappear, it becomes very bright and visible even ten minutes after sunset.

A beautiful sight is a rainbow on the dew. 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 borealis.

In most cases, auroras are green or blue-green in color, with occasional patches or borders 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 on the form of ribbons. Losing intensity, it turns into spots. However, many ribbons disappear before they 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 stars can be seen through it. The lower edge of the curtain is quite sharply and distinctly outlined and often tinted in red or pinkish color, reminiscent of the border of the curtain, the upper one is gradually lost in height and this creates a particularly spectacular impression of the depth of space.

There are four types of auroras:

Uniform arc- the luminous strip has the simplest, calmest form. It is brighter from below and gradually disappears upward against the background of the glow of the sky;

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

radiant band– with an increase in activity, larger folds are superimposed on smaller ones;

With increased activity, the folds or loops expand to enormous sizes, the lower edge of the ribbon shines brightly with a pink glow. When the activity subsides, the wrinkles disappear and the tape returns to a uniform shape. This suggests that the uniform structure is the main form of the aurora, and the folds are associated with an increase in activity.

Often there are aurora of a different kind. They capture the entire polar region and are very intense. They occur during an increase in solar activity. These lights appear as a whitish-green cap. Such lights are called flurries.

According to 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 aurora, barely noticeable and approximately equal in brightness Milky Way, the radiance of the fourth class illuminates the Earth as brightly as the full moon.

It should be noted that the aurora that has arisen propagates to the west at a speed of 1 km/sec. The upper layers of the atmosphere in the area of auroral flashes are heated and rush upwards. During auroras, eddy electric currents arise in the Earth's atmosphere, capturing large areas. They excite additional unstable magnetic fields, the so-called magnetic storms. During aurora, the atmosphere emits X-rays, which appear to be the result of electron deceleration in the atmosphere.

Intense flashes of radiance are often accompanied by sounds resembling noise, crackling. Auroras cause strong changes in the ionosphere, which in turn affects radio conditions. In most cases, radio communication deteriorates significantly. There is strong interference, and sometimes a complete loss of reception.

How do aurorae occur?

The earth is a huge magnet South Pole which is located near the northern geographic pole, and the northern one is close to the southern one. The lines of force of the Earth's magnetic field, called geomagnetic lines, leave the area adjacent to the north magnetic pole of the Earth, cover the globe and enter it in the area of the south magnetic pole, forming a toroidal lattice around the Earth.

It has long been believed that the location of the magnetic lines of force symmetrical about the earth's axis. Now it turned out that the so-called "solar wind" - a stream of protons and electrons emitted by the Sun, hits the geomagnetic shell of the Earth from a height of about 20,000 km, pulls it back, away from the Sun, forming a kind of magnetic "tail" near the Earth.

An electron or a proton that has fallen into the Earth's magnetic field moves in a spiral, as if winding itself on a geomagnetic line. Electrons and protons that have fallen from the solar wind into the Earth's magnetic field are divided into two parts. Some of them flow down the magnetic field lines immediately into the polar regions of the Earth; others get inside the teroid and move inside it, along a closed curve. These protons and electrons eventually flow along geomagnetic lines to the region of the poles, where their increased concentration occurs. Protons and electrons produce ionization and excitation of atoms and molecules of gases. To do this, they have enough energy, since protons arrive at the Earth with energies of 10000-20000 eV (1 eV = 1.6 10 J), and electrons with energies of 10-20 eV. 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.

Excited gas atoms give back the received energy in the form of light, just as it happens in tubes with a rarefied gas when currents are passed through them.

Spectral study shows that the green and red glow belongs to excited oxygen atoms, infrared and violet - to ionized nitrogen molecules. Some emission lines of oxygen and nitrogen are formed at an altitude of 110 km, and the red glow of oxygen is formed at an altitude of 200-400 km. Another weak source of red light is hydrogen atoms formed in the upper atmosphere from protons arriving from the Sun. Having captured an electron, such a proton turns into an excited hydrogen atom and emits red light.

Aurora flares usually occur a day or two after solar flares. This confirms the connection between these phenomena. Recently, scientists have found that the auroras are more intense off the coast of the oceans and seas.

But the scientific explanation of all the phenomena associated with aurora encounters a number of difficulties. For example, the exact mechanism of particle acceleration to the indicated energies is unknown, their trajectories in the near-Earth space are not quite clear, not everything converges quantitatively in the energy balance of ionization and excitation of particles, the mechanism for the formation of luminescence is not quite clear. various kinds, the origin of sounds is unclear.

Halo

Sometimes the Sun looks like it's being seen through a large lens. In fact, the image shows the effect of millions of lenses: ice crystals. As water freezes in the upper atmosphere, small, flat, hexagonal ice crystals of ice can form. The planes of these crystals, which circling, gradually descend to the ground, are oriented parallel to the surface most of the time. At sunrise or sunset, the observer's line of sight can pass through this very plane, and each crystal can lead like a miniature lens that refracts sunlight. The combined effect can lead to the appearance of a phenomenon called parhelia, or a false sun. The sun is visible in the center of the picture and two well-marked false suns are visible at the edges. Behind the houses and trees, a halo (halo - pronounced with an emphasis on "o"), about 22 degrees in size, three solar columns, and an arch created by sunlight reflected by atmospheric ice crystals.

Light and ice

Researchers have long paid attention to the fact that when a halo appears, the sun is covered with haze - a thin veil of high cirrus or cirrostratus clouds. Such clouds float in the atmosphere at a height of six to eight kilometers above the earth and consist of the smallest ice crystals, which most often have the form of hexagonal columns or plates.

The earth's atmosphere knows no rest. Ice crystals, descending and rising in air currents, sometimes reflect like a mirror, sometimes refract, like a glass prism, falling on them Sun rays. As a result of this complex optical game, false suns and other deceptive pictures appear in the sky, in which, if desired, one can see fiery swords and anything else ...

As already mentioned, more often than others, two false suns can be observed - on either side of the real star. Sometimes there is one light circle, slightly colored in iridescent tones, encircling the sun. And then after sunset, a huge luminous column suddenly appears in the darkened sky.

Not all cirrus clouds give a bright, well-marked halo. To do this, it is necessary that they are not too dense (the sun shines through) and at the same time there must be a sufficient amount of ice crystals in the air. However, a halo can also appear in a completely clear, cloudless sky. This means that there are many individual ice crystals floating high in the atmosphere, but no cloud formation. This happens on winter days when the weather is clear and frosty.

...A bright horizontal circle appeared in the sky, encircling the sky parallel to the horizon. How did it come about?

Special experiments (they have been repeatedly carried out by scientists) and calculations show that this circle is the result of the reflection of sunlight from the side faces of hexagonal ice crystals floating in the air in a vertical position. The rays of the sun fall on such crystals, are reflected from them, like from a mirror, and fall into our eyes. And since this mirror is special, it is composed of an innumerable mass of ice particles and, moreover, for some time appears to lie in the plane of the horizon, then the reflection solar disk we see in the same plane. It turns out two suns: one is real, and next to it, but in a different plane - its twin in the form of a large bright circle.

It happens that such a reflection of sunlight from small ice crystals floating in the frosty air gives rise to a luminous column. It turns out this is because crystals in the form of plates participate in the play of light here. The lower edges of the plates reflect the light of the sun that has already disappeared behind the horizon, and instead of the sun itself, we see a luminous path going into the sky from the horizon for some time - an image of the solar disk distorted beyond recognition. Each of us observed something similar on a moonlit night, standing on the shore of the sea or lake. Admiring the lunar path, we see the same play of light on the water - mirror reflection moon, strongly stretched due to the fact that the surface of the water is covered with ripples. Slightly agitated water reflects the moonlight falling on it in such a way that we perceive, as it were, many dozens of individual reflections of the moon, from which the moon path glorified by poets is formed.

You can often observe the lunar halo. This is a fairly common sight and occurs if the sky is covered with high thin clouds with millions of tiny ice crystals. Each ice crystal acts as a miniature prism. Most crystals are in the form of elongated hexagons. Light enters through one front surface of such a crystal and exits through the opposite one with a refraction angle of 22º.

And watch street lamps in winter, and you may be lucky enough to see the halo generated by their light, under certain conditions, of course, namely in frosty air saturated with ice crystals or snowflakes. By the way, a halo from the sun in the form of a large light pillar can also occur during a snowfall. There are days in winter when snowflakes seem to float in the air, and sunlight stubbornly breaks through loose clouds. Against the background of the evening dawn, this pillar sometimes looks reddish - like a reflection of a distant fire. In the past, such a completely harmless phenomenon, as we see, horrified superstitious people.

Prism crystals

Perhaps someone has seen such a halo: a bright, iridescent-colored ring around the sun. This vertical circle occurs when there are many hexagonal ice crystals in the atmosphere, which do not reflect, but refract the sun's rays like a glass prism. In this case, most of the rays, of course, are scattered and do not reach our eyes. But some part of them, having passed through these prisms in the air and refracted, reaches us, so we see a rainbow circle around the sun. Its radius is about twenty-two degrees. Sometimes more - at forty-six degrees.

Why rainbow?

As you know, passing through a prism, a white light beam decomposes into its spectral colors. Therefore, the ring formed by refracted rays around the sun is painted in iridescent tones: its inner part is reddish, the outer is bluish, and inside the ring the sky seems darker.

It is noticed that the halo circle is always brighter on the sides. This is because two halos intersect here - vertical and horizontal. And false suns are formed most often at the intersection. The most favorable conditions for the appearance of false suns are formed when the sun is not high above the horizon and part of the vertical circle is no longer visible to us.

What kind of crystals are involved in this "performance"?

The answer to the question was given by special experiments. It turned out that false suns appear due to hexagonal ice crystals, shaped like ... nails. They float vertically in the air, refracting the light with their side faces.

The third "sun" appears when only one upper part of the halo circle is visible above the real sun. Sometimes it is a segment of an arc, sometimes a bright spot of an indefinite shape. Sometimes false suns are not inferior in brightness to the Sun itself. Observing them, the ancient chroniclers wrote about three suns, about severed fiery heads, and so on.

In connection with this phenomenon, a curious fact has been recorded in the history of mankind. In 1551, the German city of Magdeburg was besieged by the troops of the Spanish king Charles V. The defenders of the city held firm, the siege had lasted for more than a year. Finally, the irritated king gave the order to prepare for a decisive attack. But then an unprecedented thing happened: a few hours before the assault, three suns shone over the besieged city. The mortally frightened king decided that heaven was protecting Magdeburg and ordered the siege to be lifted.

Mirage

The simplest mirages were seen by any of us. For example, when driving on a heated paved road, far ahead it looks like a water surface. And this does not surprise anyone for a long time, because mirage- nothing more than an atmospheric optical phenomenon, due to which images of objects appear in the visibility zone, which under normal conditions are hidden from observation. This happens because light is refracted when passing through layers of air of different densities. Remote objects at the same time, they may turn out to be raised or lowered relative to their actual position, and they may also be distorted and acquire irregular, fantastic forms.

From the greater variety of mirages, we single out several types: “lake” mirages, also called inferior mirages, superior mirages, double and triple mirages, ultra-long-range vision mirages.

Explanation of the lower ("lake") mirage.

Lake, or inferior mirages are the most common. They appear when distant, almost Smooth surface the desert takes shape open water, especially when viewed from a slight elevation or just above a layer of heated air. A similar illusion arises, as on an asphalt road.

If the air at the very 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.

According to the established rule, light rays near the surface of the earth will be in this case bend so that their trajectory is convex downward. Light beam from some area blue sky enters the eye of the observer, having experienced a curvature. And 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 he has an image of a blue sky in front of him. If we imagine that there are hills, palm trees or other objects near the horizon, then the observer will see them upside down due to the curvature of the rays, and will perceive them as reflections of the corresponding objects in non-existent water. The jitter of the image, caused by fluctuations in the refractive index of hot air, creates the illusion of flowing or undulating water. So there is an illusion, which is a "lake" mirage.

As reported in one article in Jour-

nale The New Yorker, a pelican, having rendered

hovering over a hot asphalt highway

in the US Midwest, almost once

fought when he saw in front of him such a "leading

noah mirage. "The unfortunate bird flew,

maybe many hours over dry

wheat stubble and suddenly see

something that seemed to her a long, black, not wide, but real river - in the very heart of the prairie. The pelican rushed down to swim in the cool water - and lost consciousness, hitting the asphalt. Below eye level, objects, usually upside down, may appear in this "water". Above the heated surface of the land, an “air layer cake” is formed, and the layer closest to the earth is the most heated and so rarefied that light waves passing through it are distorted, since their propagation speed varies depending on the density of the medium.

superior mirages

Upper mirages, or, as they are also called, distant vision mirages, are less common and more picturesque than lower mirages. Distant objects (often below the sea horizon) appear upside down in the sky, and sometimes a direct image of the same object also appears above. This phenomenon is typical for cold regions, especially when there is a significant temperature inversion, when a warmer layer of air is above the colder layer. The optical effect manifests itself as a result of the propagation of the front of light waves in layers of air with a non-uniform density. Very unusual mirages occur from time to time, especially in the polar regions. When mirages occur on land, trees and other landscape components are upside down. In all cases, objects in the upper mirages are more clearly visible than in the lower ones. There are places on the globe where, before evening, mountains can be seen rising above the ocean horizon. These are really mountains, only they are so far away that they cannot be seen in normal conditions. In these mysterious places, shortly after noon, a blurry outline of mountains begins to appear on the horizon. It gradually grows and before sunset quickly becomes sharp, distinct, so that you can even distinguish individual peaks.

Superior 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, a simple one and an inverted one. These images may be separated by a strip of air (one may be above the horizon, the other below it), but may directly merge with each other. Sometimes there is another - the third image.

Double and triple mirages

If the refractive index of air changes first quickly and then slowly, then the rays will bend faster. The result is two images. Light rays propagating within the first air region form an inverted image of the object. Then these rays, propagating mainly within the second region, are bent to a lesser extent and form a straight image.

To understand how a triple mirage appears, one must imagine three consecutive air regions: the first (near the surface), where the refractive index decreases slowly with height, the next, where the refractive index decreases rapidly, and the third region, where the refractive index decreases slowly again. First, the rays form the lower image of the object, propagating within the first air region. Next, the rays form an inverted image; falling into the second air region, these rays experience a strong curvature. The rays then form the top direct image of the object.

Mirage of ultra-long vision

The nature of these mirages is the least studied. It is clear that the atmosphere must be transparent, free from water vapor and pollution. But this is not enough. A stable layer of cooled air should form at some height above the ground. Below and above this layer, the air should be warmer. A light beam that has got inside a dense cold layer of air should be, as it were, “locked” inside it and propagate in it like a kind of light guide.

What is the nature of Fata Morgana - the most beautiful of the mirages? When a layer of cold air forms over warm water, magical castles appear over the sea, which change, grow, and disappear. Legend has it that these castles are the crystal home of the fairy Morgana. Hence the name.

An even more mysterious phenomenon is chronomirages. None known laws physicists cannot explain why mirages can reflect events occurring at some distance, not only in space, but also in time. The mirages of battles and battles that once took place on earth were especially famous. In November 1956, several tourists spent the night in the mountains of Scotland. At about three o'clock in the morning they woke up from a strange noise, looked out of the tent and saw dozens of Scottish archers in ancient military uniforms, who, shooting, fled through a rocky field! Then the vision disappeared, leaving no traces, but a day later it happened again. The Scottish archers, all wounded, plodded across the field, stumbling over the stones. They must have been defeated in battle and retreated.

And this is not the only evidence of this phenomenon. So, the famous battle of Waterloo (June 18, 1815) was observed a week later by the inhabitants of the Belgian town of Verviers. K. Flammarion in his book “Atmosphere” describes an example of such a mirage: “Based on the testimony of several credible persons, I can report a mirage that was seen in the city of Verviers (Belgium) in June 1815. One morning, the inhabitants of the city saw in the sky army, and it is so clear that it was possible to distinguish the suits of artillerymen and even, for example, a cannon with a broken wheel, which is 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 cases when such mirages were observed at large distances - up to 1000 km. " Flying Dutchman” should be attributed to such mirages.

Scientists called one of the varieties of chronomirage "drossolides", which means "dew drops" in Greek. It has been noted that chronomirages most often occur in the early morning hours, when fog droplets condense in the air. The most famous "drossolides" occurs quite regularly on the coast of Crete in the middle of summer, usually in the early morning. There are many eyewitness accounts who observed how a huge “battle canvas” appeared over the sea near the castle of Franca-Castello - hundreds of people who came together in a deadly battle. Screams are heard, the sound of weapons. During the Second World War, the "battle of ghosts" terribly frightened the German soldiers who fought then in Crete. The Germans opened heavy fire from all types of weapons, but did not cause any harm to the phantoms. A mysterious mirage is slowly approaching from the sea and disappears into the walls of the castle. Historians say that in this place about 150 years ago there was a battle between the Greeks and the Turks, its image, lost in time, is observed over the sea. This phenomenon can be observed quite often in the middle of summer, in the early hours.

By the way, today eyewitnesses often observe not only the battles of bygone times and once-existing ghost towns, but phantom cars. A few years ago, a group of Australians met on a night road a car that had once crashed there, driven by their deceased friend. However, not only he was sitting in the ghostly car, but also his young girlfriend, who survived that catastrophe and is now in good health, becoming a respectable lady.

What is the nature of such mirages?

According to one theory, with a special confluence natural factors visual information is imprinted in time and space. And with the coincidence of certain atmospheric, weather, etc. conditions, it again becomes visible to outside observers. According to another theory, in the area of battles in which thousands of people participate (and die), huge psychic energy accumulates. Under certain conditions, it "discharges" and visibly shows past events.

In general, the ancient Egyptians, for example, believed that a mirage is a ghost of a country that no longer exists in the world.

Legend of the Alps

A group of tourists climbed one of the mountain peaks. The people were all young, with the exception of the guide, an old highlander. At first, everything went quickly and cheerfully. But the higher climbers climbed, the more difficult it became to go. Soon each of them felt very tired. Only the guide walked, as before, deftly jumping over the crevices, quickly and easily climbing the ledges of the rocks.

A wonderful picture opened up around. Wherever the eye could see, snow-capped mountain peaks rose. The nearest ones glittered in the rays of the blinding sun. The distant peaks appeared bluish. Down went steep slopes, turning into gorges. Light green alpine meadows stood out as bright spots.

Finally they reached one of the side peaks of the mountain they were climbing. The sun had already descended to the horizon, and its rays fell on people from the bottom up. And then the unexpected happened.

One of the young men overtook the guide and was the first to climb to the top. At the same moment as he stepped onto the rock, in the east, against the backdrop of clouds, a huge shadow of a man appeared. It was visible so clearly that people stopped as if on cue. But the guide calmly looked at the gigantic shadow, at the young people frozen in fright, and, grinning, said:

- Do not be afraid! It happens, - and he also climbed a rock.

As he stood next to the tourist, another large human shadow appeared in the clouds.

The guide took off his warm felt hat and waved it. One of the shadows repeated his movement: a huge hand rose to his head, took off his hat and waved it. The young man raised his stick up. His gigantic shadow did the same. After that, each of the tourists wanted, of course, to climb the rock and see their shadow in the air. But soon clouds obscured the sun, which was sinking below the horizon, and the unusual shadows disappeared.

Parade of superstitions

Now, I think, it will not be difficult to understand how luminous crosses appear in the sky, which even in our century frighten other people.

The key here is that we do not always see this or that form of a halo completely in the sky. In winter, during severe frosts, as already mentioned, two bright spots appear on both sides of the sun - parts of a vertical halo circle. This is also the case with a horizontal circle passing through the sun. Most often, only that part of it that adjoins the luminary is visible - in the sky one can see, as it were, two light tails stretching from it to the right and left. At the same time, parts of the vertical and horizontal circles intersect and form, as it were, two crosses on both sides of the sun.

In another case, we see a part of a horizontal circle near the sun, intersected by a luminous column, which goes up and down from the sun. And the cross is formed again.

Finally, it also happens that a luminous pillar and the upper part of a vertical circle are visible in the sky after sunset. Intersecting, they also give the image of a large cross. And sometimes such a halo resembles an old knight's sword. And if it is still painted by the dawn, then here is a bloody sword for you - as if a formidable reminder of heaven about future troubles!

Scientific explanation of the halo - a prime example how deceptive is sometimes the external form of any natural phenomenon. It seems that something is extremely mysterious, mysterious, but if you figure it out, there is not a trace left of the “inexplicable”.

It's easy to say - you'll understand! It took years, decades, centuries. Today, every person, interested in something, can look into the reference book, leaf through the textbook, immerse himself in the study special literature. Finally ask! But were there such opportunities in the middle, say, centuries? After all, then such knowledge had not yet been accumulated, and loners were engaged in science. Religion was the dominant worldview, and faith was the usual worldview.

The French scientist K. Flammarion looked through the historical chronicles from this angle. And this is what turned out: the compilers of the chronicles did not at all doubt the existence of a direct causation between mysterious phenomena nature and earthly affairs.

In 1118, during the reign of King Henry I of England, two full moons, one in the west and the other in the east. In the same year, the king was victorious in battle.

In 1120, a cross and a man appeared among the blood-red clouds, consisting of flames. That same year it rained blood; everyone was expecting the doomsday, but the matter ended only in civil war.

In 1156, three rainbow circles shone around the sun for several hours in a row, and when they disappeared, three suns appeared. The compiler of the chronicle saw in this phenomenon an allusion to the king's quarrel with the Bishop of Canterbury in England and to the destruction after the seven-year siege of Milan in Italy.

The following year, three suns reappeared, and a white cross was visible in the middle of the moon; of course, the chronicler immediately associated this with the strife that accompanied the election of a new pope.

In January 1514, three suns were visible in Württemberg, of which the average is larger than the side ones. At the same time, bloody and flaming swords appeared in the sky. In March of the same year, three suns and three moons were again visible. Then the Turks were defeated by the Persians in Armenia.

In 1526, at night in Württemberg, bloodied military armor was visible in the air ...

In 1532, near Innsbruck, wonderful images of camels were seen in the air, wolves spitting fire, and, finally, a lion in a circle of fire ...

Whether all these phenomena actually existed is not so important for us now. It is important that with their help, on their basis, real historical events were interpreted; that people then looked at the world through the prism of their distorted ideas and therefore saw what they wanted to see. Their imagination sometimes knew no bounds. Flammarion called the incredible fantastic paintings painted by the authors of the chronicles "exemplars of artistic exaggeration." Here is one of those samples:

“... In 1549, the moon was surrounded by halo and paraselens (false moons), near which they saw a fiery lion and an eagle tearing its own chest. Following this, burning cities appeared, camels, Jesus Christ on an armchair with two thieves on the sides, and, finally, a whole assembly - apparently, the apostles. But last change phenomena was the worst. A man of enormous stature, of a cruel appearance, appeared in the air, threatening with a sword a young girl who was crying at his feet, asking for mercy ... "

What eyes were needed to see all this!

Some mysteries of optical phenomena

color on glass

Winter evening. Slight frost - about 10 °. You are traveling by tram (or by bus, it doesn't matter). The window starts to freeze. You can’t see anything through the glass, but the light of the lanterns is very clear. And at some point, the light of a street lamp calls on a frozen window wonderful game colors. The shades are so pure and beautiful that no artist can accurately reproduce them. After a few seconds, the layer of ice on the window reaches a thickness of a few tenths of a millimeter and the colors disappear. But that's not a problem. Wipe off the frozen layer with your hand and repeat the observation - the colors will reappear.

Please note: a lantern with an incandescent lamp gives a purple-emerald halo, and a fluorescent lamp (mercury-quartz) is surrounded by a halo of yellow-violet flowers.

This physical phenomenon has not yet been studied enough, and there is no exact explanation for it, however, it can be assumed that the play of color is caused by interference (the addition of light reflected from the upper and lower surfaces of the thinnest layer of moisture vapor frozen on the window glass).

This phenomenon is similar to what we observe when we look at the iridescent rainbow soap bubble.

colored rings

Draw a circle with black ink on a sheet of thick paper, on which a semicircle and arc stripes are located. Stick it on cardboard and make a top. When this top is rotated, instead of black drawings, multi-colored rings will appear (purple, pink, blue or green, purple). The order of their arrangement varies depending on the direction of rotation of the top. The experiment is best carried out under electric lighting.

If this experience were shown on television, the effect would be the same: on a black-and-white TV screen, you would see multi-colored rings. Why this happens is unknown. Scientists have not yet found an explanation for this phenomenon.

Conclusion: The physical nature of light has interested people since time immemorial. Many eminent scientists, throughout the development of scientific thought, struggled to solve this problem. Over time, the complexity of the ordinary white beam, and its ability to change its behavior depending on environment, and his ability to show signs inherent in both material elements and the nature of electromagnetic radiation. The light beam, subjected to various technical influences, began to be used in science and technology in the range from a cutting tool capable of processing the desired part with an accuracy of a micron, to a weightless information transmission channel with practically inexhaustible possibilities.

But, before the modern view of the nature of light was established, and the light beam found its application in human life, many optical phenomena that occur everywhere in the earth's atmosphere were identified, described, scientifically substantiated and experimentally confirmed, from the rainbow known to everyone to complex, periodic mirages. But, despite this, the bizarre play of light has always attracted and still attracts a person. Neither the contemplation of the winter halo, nor the bright sunset, nor the wide, half-sky strip of the northern lights, nor the modest moonlit path on the water surface leaves anyone indifferent. A light beam, passing through the atmosphere of our planet, not only illuminates it, but also gives it a unique look, making it beautiful.

Of course, much more optical phenomena occur in the atmosphere of our planet, which are discussed in this essay. Among them there are both well-known to us and solved by scientists, and those who are still waiting for their discoverers. And we can only hope that, over time, we will witness more and more new discoveries in the field of optical atmospheric phenomena, indicating the versatility of an ordinary light beam.

Literature:

5. "Physics 11", N. M. Shakhmaev, S. N. Shakhmaev, D. Sh. Shodiev, Prosveshchenie publishing house, Moscow, 1991.

6. "Solution of problems in physics", V. A. Shevtsov, Nizhne-Volzhskoe book publishing house, Volgograd, 1999.

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Optical phenomena in the atmosphere. Electrical and optical phenomena in the atmosphere

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