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 types of optics, as a physical phenomenon, are available to our observation only when using special technical devices. These can be laser installations, X-ray emitters, radio telescopes, plasma generators, and many others. 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 the greatest density at 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 celestial bodies, the earth's atmosphere is a kind of optical system with constantly changing parameters. 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 its greatest development at a depth of the Sun under the horizon of about 4-5 o . 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 clearly against the background of the fading sky, and only at the horizon, where the Sun has disappeared, 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.

Various optical (light) phenomena in the atmosphere are due to the fact that the light rays of the sun and other celestial bodies, passing through the atmosphere, experience scattering and diffraction. In this regard, a number of amazingly beautiful optical phenomena occur in the atmosphere:

the color of the sky, the color of the dawn, twilight, the twinkling of stars, circles around the apparent location of the sun and moon, a rainbow, a mirage, etc. All of them, reflecting certain physical processes in the atmosphere, are very closely related to the change and state of the weather and therefore can add up as good local signs for her prediction.

As you know, the spectrum of sunlight consists of seven primary colors, red, orange, yellow, green, blue, indigo and violet. Various colors of white light rays are mixed in a strictly defined proportion. With any violation of this proportion, the light turns from white to colored. If rays of light fall on particles whose dimensions are smaller than the wavelengths of the rays, then, according to Rayleigh's law, they are scattered by these particles in inverse proportion to the wavelengths to the fourth power. These particles can be both molecules of gases that make up the atmosphere, and the smallest particles of dust.

The same particles scatter rays of different colors in different ways. Violet, blue and blue rays are scattered most strongly, red ones are weaker. That is why the sky is colored blue: at the horizon it has a light blue tone, and at the zenith it is almost blue.
Blue rays, passing through the atmosphere, are strongly scattered, while red rays reach the surface of the earth almost completely unscattered. This explains the red color of the solar disk at sunset or just after sunrise.

When light falls on particles whose diameter is almost equal to or greater than the wavelengths, then the rays of all colors are scattered equally. In this case, the scattered and incident light will be the same color.
Therefore, if larger particles are suspended in the atmosphere, then white will be added to the blue color of the sky, due to the scattering of gas molecules, and the sky will become blue with a whitish tint, increasing as the number of particles suspended in the atmosphere increases.
This color of the sky is observed when there is a lot of dust in the air.
The color of the sky becomes whitish, and if there are large amounts of condensation products of water vapor in the air in the form of water droplets, ice crystals, the sky acquires a reddish and orange tint.
This phenomenon is usually observed during the passage of fronts or cyclones, when moisture is carried high up by powerful air currents.

When the sun is near the horizon, the rays of light have to travel a long way to the surface of the earth in a layer of air, often containing a large amount of large particles of moisture and dust. In this case, blue light is scattered very weakly, red and other rays are more strongly scattered, coloring the lower layer of the atmosphere in various bright and brown shades of red, yellow and other colors, depending on the dust content, humidity and dryness of the air.

Closely related to the color of the sky is a phenomenon called opalescent haze. The phenomenon of opalescent turbidity of the air consists in the fact that distant earthly objects seem to be shrouded in a bluish haze (scattered violet, blue, blue colors).
This phenomenon is observed in those cases when the air is in a suspended state (a lot of tiny dust particles with a diameter of less than 4 microns.

Numerous studies of the color of the sky using a special device (cyanometer) and visually established the relationship between the color of the sky and the nature of the air mass. It turned out that there is a direct relationship between these two phenomena.
A deep blue color indicates the presence of an arctic air mass in the area, and a whitish color indicates a dusty continental and tropical one. When, as a result of the condensation of water vapor in the air, particles of water or ice crystals larger than air molecules are formed, they reflect all the rays equally, and the sky becomes whitish or grayish in color.

Solid and liquid particles in the atmosphere cause significant haze in the air and therefore greatly reduce visibility. The visibility range in meteorology is understood as the limiting distance at which, under a given state of the atmosphere, the objects under consideration cease to be distinguishable.

Therefore, the color of the sky and visibility, which depend largely on the size of particles in the air, make it possible to judge the state of the atmosphere and the upcoming weather.

A number of local signs of weather prediction are based on this:

Dark bluish skies during the day (only near the sun can be slightly whitish), moderate to good visibility, and calm weather result in little water vapor in the troposphere, so anticyclone weather can be expected to last 12 hours or more.

A whitish sky during the day, average or poor visibility indicate the presence of a large amount of water vapor, condensation products and dust in the troposphere, i.e., the periphery of the anticyclone passes here, in contact with the cyclone: ​​we can expect a transition to cyclonic weather in the next 6-12 hours.

The color of the sky, which has a greenish tint, indicates the great dryness of the air in the troposphere; In summer, it portends hot weather, and in winter, frosty.

An even gray sky in the morning precedes clear good weather, a gray evening and a red morning precede stormy windy weather.

The whitish hue of the sky near the horizon at low altitude (while the rest of the sky is blue) has a slight dampness in the troposphere and portends good weather.

A gradual decrease in the brightness and blueness of the sky, an increase in a whitish spot near the sun, clouding of the sky near the horizon, deterioration in visibility is a sign of the approach of a warm front or a warm-type occlusion front.

If distant objects are clearly visible and do not seem closer than they really are, anticyclonic weather can be expected.

If distant objects are clearly visible, but the distance to them seems closer than the actual one, then there is a large amount of water vapor in the atmosphere: you need to wait for the weather to worsen.

Poor visibility of distant objects on the coast indicates the presence of a large amount of dust in the lower air layer and is a sign that precipitation should not be expected in the next 6-12 hours.

High air transparency with a visibility range of 20-50 km or more is a sign of the presence of an arctic air mass in the area

The clear visibility of the moon with an apparent bulging disk indicates high air humidity in the troposphere and is a sign of worsening weather.

A well-visible ashy moonlight portends bad weather. Ash light is a phenomenon when, in the first days after the new moon, in addition to the narrow bright crescent of the moon, its entire full disk is visible, dimly illuminated by light reflected from the earth.

Dawn

Dawn is the color of the sky at sunrise and sunset.

The variety of colors of dawn is caused by different conditions of the atmosphere. The colored stripes of dawn, counting from the horizon, are always observed in the order of the colors of the spectrum red, orange, yellow, blue.
Individual colors may be completely absent, but the order of distribution never changes. The horizon below red may sometimes have a gray dirty purple that appears lilac. The upper part of the dawn is either whitish or blue.

The main factors affecting the appearance of dawn are the products of water vapor condensation and dust contained in the atmosphere:

The more moisture in the air, the more pronounced the red color of the dawn. An increase in air humidity is usually observed before the approach of a cyclone, a front that brings inclement weather. Therefore, with bright red and orange dawns, wet weather with strong winds can be expected. The predominance of yellow (golden) tones of dawn indicates a small amount of moisture and a large amount of dust in the air, which indicates the upcoming dry and windy weather.

Bright and purple-red dawns, similar to the glow of a distant fire with cloudy hues, indicate high air humidity and are a sign of worsening weather - the approach of a cyclone, a front in the next 6-12 hours.

The predominance of bright yellow, as well as golden and pink tones of the evening dawn, indicates a low humidity of the air; dry, often windy weather can be expected.

Light red (pink) sky in the evening indicates light windy weather without precipitation.

A ruddy evening and a gray morning portend a clear day and an evening with light winds.

The more tender the red color of the clouds at evening dawn, the more favorable the upcoming weather will be.

A yellowish-brown dawn in winter during frost indicates their persistence and possible intensification.

A cloudy yellowish pink evening dawn is a sign of a likely deterioration in the weather.

If the sun, approaching the horizon, little changes its usual whitish-yellow color and sets very bright, which is associated with a high transparency of the atmosphere, a low content of moisture and dust, then good weather will continue.

If the sun, before setting to the horizon, or at sunrise at the moment when its edge appears, gives a flash of a bright green ray, then we must expect the preservation of stable, clear, calm weather; if you managed to notice a blue beam at the same time, then you can expect it. Especially quiet and clear weather. The duration of the flash of the green beam is no more than 1-3 seconds.

The predominance of greenish shades during the evening dawn indicates a long dry clear weather.

A light silvery strip without any sharp boundaries, visible for a long time at the horizon in a cloudless sky after sunset, portends a long calm anticyclonal weather.

The gentle pink illumination of motionless cirrus clouds during the setting of the salt in the absence of other clouds is a reliable sign of established anticyclonic weather.

The predominance of a bright red color in the evening dawn, which persists for a long time as the sun further sinks below the horizon, is a sign of the approach of a warm front or a warm-type occlusion front; one should expect prolonged inclement windy weather.

A gently pink dawn in the form of a circle above the sun that has set beyond the horizon is good stable weather. If the color of the circle turns pink-red, precipitation and increased wind are possible.

The color of the dawn is closely related to the nature of the air mass. The table compiled for the temperate latitudes of the European part of the CIS shows the relationship between the colors of dawn and air masses according to N. I. Kucherov:

Sunset

Since cyclones move mainly from the western points, the appearance of clouds in the western half of the sky is usually a sign of the approach of a cyclone, and if this happens in the evening, then the sun sets into the clouds. But at the same time, it is necessary to take into account the sequence of cloud forms, which is associated with cyclones, atmospheric fronts.

If the sun sets behind a low solid cloud that stands out sharply against the background of a greenish or yellowish sky, then this is a sign of upcoming good (dry, calm and clear) weather.

If the sun sets with continuous low cloudiness and if layers of cirrus or cirrostratus clouds are observed on the horizon and above the cloudiness, then precipitation will fall, windy cyclonic weather will occur in the next 6-12 hours.

Sunset behind dark dense clouds with a red color at the edges heralds cyclonic weather.

If, after sunset, a dark cone gradually spreading upwards with a wide blurred orange border is clearly visible in the east - the shadow of the earth, then a cyclone is approaching from the sunset side.

The shadow of the earth in the east after sunset is grey-gray, without a colored edge or with a pale pink color - a sign of the persistence of anticyclonic weather.

This is the name given to a beam of individual light rays or bands coming out from behind the clouds covering the sun. The rays of the sun pass through the gaps between the clouds, illuminate the water droplets floating in the air in suspension, and give a bunch of light bands in the form of ribbons (Buddha rays).

Since this radiance is observed due to the presence of a large number of small water droplets in the air, it portends rainy, windy cyclonic weather.

The radiance emerging from behind a dark cloud, behind which the sun is located, is a sign of the onset of windy weather with rain in the next 3-6 hours.

The radiance due to yellow clouds, observed immediately after the last rain, portends the imminent resumption of rain and increased wind.

The red color of the sun, moon and other celestial bodies indicates a high humidity in the atmosphere, i.e. establishment in the next 6-10 hours of cyclonic weather with strong winds and precipitation.

The reddish color of the darkened disk of the sun, together with the bluish color of distant objects (mountains, etc.) is a sign of the spread of dusty tropical air, and a significant increase in air temperature should be expected soon.

Observing the vault of heaven from an open place (for example, in the sea), you can see that it has the shape of a hemisphere, but flattened in the vertical direction. It often seems that the distance from the observer to the horizon is three to four times greater than to the zenith.

This is explained as follows. When looking up, without tilting the head back, objects appear to us shortened compared to those that are in a horizontal position.

For example, fallen poles or trees appear longer than vertical ones. In the horizontal direction, atmospheric perspective acts, due to which objects shrouded in haze (from dust and ascending currents) seem less illuminated and therefore more distant.

The apparent oblateness of the firmament varies depending on the weather conditions. Great transparency of the atmosphere and high humidity increase the flattening of the sky.

A flattened, low vault of heaven is seen before cyclonic weather.

A high vault of heaven is observed in the central regions of anticyclones; it can be expected that good anticyclonic weather will persist for 12 hours or more.

Back forward

Attention! The slide preview is for informational purposes only and may not represent the full extent of the presentation. If you are interested in this work, please download the full version.

The purpose of the lesson: to form an idea of ​​\u200b\u200boptical phenomena in the atmosphere.

Expected result: students should know / understand and explain how atmospheric phenomena occur due to the reflection of sunlight; electrical phenomena.

Basic terms and concepts: optical phenomena in the atmosphere, rainbow, mirage, halo, aurora, lightning, “St. Elmo's Lights”.

Resources:
– textbook – pp. 106–109;
– electronic supplement to the textbook;
– presentation for the lesson.

Equipment:
- Projector;
- Screen;
- The teacher's computer;
– Laptops on each desk;
– Vessel in oriental style;
- Suit for Old Man Hottabych.

During the classes

- 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? (Atmosphere is the air envelope of the Earth.)

And we continue to study the topic “Atmosphere” with you. First, I'll ask you a few questions:

1. What does the Earth's atmosphere consist of? (A mixture of gases, tiny drops of water and ice crystals, dust, soot, organic matter.)

2. In what form is moisture contained in the air? (Water vapor, water droplets and ice crystals.)

3. The atmosphere is not homogeneous, does it have several layers? (Tropo-strato-meso-thermo-exo-ionosphere.)

4. In what layers does the aurora appear? (Ionosphere.)

- Polar lights, lightning, mirages frightened people in ancient times. Today, scientists have managed to uncover the secrets of these mysterious phenomena. And the topic of our lesson is “Optical phenomena in the atmosphere”.

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

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

– Apchi! Greetings, my wise lord! (Dalley words Hottabycha, 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 in all four countries of the world genie Gassan Abdurahman ibn Hottab, that is, the son of Hottab!
- Hottabych?!
– And who are these beautiful youths?
- BUT these are students of the 6th "A" class, 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 and among the students of all schools in your region!
– We are very happy about this, dear Hottabych.
– And what are these magical black boxes that lie in front of you?
– These are computers with which today's children learn geography. I invite you, dear Hottabych, to work with us today. And I will ask the guys to open the screen of the lesson "Optical phenomena in the Atmosphere. What do you think, what are optical phenomena? (light, visual).
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 ancient scientists represented this or that phenomenon.

So let's get started!

Phenomena associated with the reflection of sunlight.

Rainbow - The summer rain had passed, and the sun shone again. And as if by magic, a rainbow-arc appeared in the sky.

I know that the god of ancient Babylon created the rainbow as a sign that he decided to stop the Flood.

What do modern scientists think about this?

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. (make an entry in the table).

– Many desert travelers witness another atmospheric phenomenon -Mirage.

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

(Children study this section in the electronic application and say the modern version)

Why do mirages occur? 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).

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

“It means that at this time there is a sabbath of witches.

(Children study this section in the electronic application and say the modern version.)

They occur when light is reflected in the ice crystals of cirrostratus clouds. Crowns - several rings nested in each other. (Records.)
Air does not conduct electricity, but in some cases it is found that it is simply overflowing with electricity.

Phenomena associated with electricity.

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

- E then self-luminous air exits through a hole in the Earth.

(Children study this section in the electronic application and say the modern version.)

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

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

- It is God Perun who strikes a snake with his stone weapon.

(Children study this section in the electronic application and say the modern version.)

A visible electrical discharge between clouds, or between a cloud and the ground. Lightning Thunder. Air can heat up inside lightning up to 30.000 gr. (This is 5 times more than on the surface of the Sun.)

Types of lightning (linear and ball), why are they dangerous? (Records.)

Another phenomenon associated with the electric glow of the atmosphere

"Fire of Saint Elmo".

Sailors consider it a bad omen.

(Children study this section in the electronic application and say the modern version.)

Today we got acquainted with some unusual phenomena in nature.

– Thanks to Hottabych, we learned about the views of the ancients on optical phenomena in the atmosphere.

– Well, I found out how your modern scientists explain many mysterious phenomena.

(If there is time: I suggest you test yourself with a quiz.)

Today you did a good job, this topic is very complex, and you will study it more deeply in the course of physics in grades 10-11.

D.Z. : Take the quiz for this lesson.

For those who wish: find out from additional sources of information what unusual atm. phenomena have ever taken place in your area. How are they described?

Electrical and optical phenomena in the atmosphere. atmospheric phenomena. Electrical and optical phenomena in the atmosphere are amazing and sometimes dangerous atmospheric phenomena.

Electrical phenomena in the atmosphere.

3. Electrical phenomena is a manifestation of atmospheric electricity (thunderstorm, lightning, aurora).

Thunderstorm - strong electrical discharges occurring in the atmosphere. Accompanied by gusty winds, heavy rain, flashes of bright light (lightning), and harsh sound effects (thunder). Thunder rumbles can be heard at a distance of up to twenty kilometers. The reason is cumulonimbus clouds. Electric discharges can occur between clouds, within the clouds themselves, between clouds and the earth's surface. A thunderstorm can be frontal during the movement of a cold or warm front of air masses or intramass. An intramass thunderstorm is formed when the air is heated locally. A thunderstorm is a very dangerous natural phenomenon for humans. In terms of the number of human lives claimed, a thunderstorm is in second place after floods. Curious scientists have determined that one and a half thousand thunderstorms occur simultaneously on Earth. Forty-six lightning strikes every second! Only at the poles and in the polar regions there is no thunderstorm.

Zarnitsa This is a light phenomenon in which clouds or the horizon are illuminated by lightning for a short time. Lightning itself is not observed. The reason is a far-reaching thunderstorm (at a distance of more than twenty kilometers). Thunder during lightning is not audible.

Polar Lights- multi-colored glow of the night sky at high latitudes. The reason is a significant fluctuation of the Earth's magnetic field. This releases a large amount of energy. The duration of this phenomenon can be from several minutes to several days.

Optical phenomena in the atmosphere.

4. Optical phenomena are the result of diffraction (refraction) of light from the Sun or the Moon (mirage, rainbow, halo).

Mirage is the appearance of an imaginary image of a really existing object. Usually imaginary objects appear upside down or heavily distorted. The reason is the curvature of the light rays due to the optical inhomogeneity of the air. Atmospheric heterogeneity appears when the air is heated unevenly at different heights.

Rainbow- a large multi-colored arc against the background of rain clouds. The outer part of the rainbow is red and the inner part is purple. Often, a secondary rainbow appears on the outside of the rainbow, in which the reverse alternation of colors. The reason for the occurrence is the refraction and reflection of light rays in droplets of water vapor. Rainbows can only be seen when the sun is low on the horizon.

Halo- light reddish arcs, circles, spots that appear around the Sun or Moon. The reason for the occurrence is the refraction and reflection of light rays from ice crystals in cirrostratus clouds.

5. Unclassified atmospheric phenomena are all phenomena that are difficult to attribute to any other type (squall, tornado, whirlwind, haze).

Squall it is an unexpected and sharp increase in wind within one or two minutes. The wind reaches speeds of more than 10 meters per second. The reason is the movement of ascending and descending air masses. The squall is accompanied by thunderstorms, heavy rain and cumulonimbus clouds.

Vortex is the rotational and translational movement of large masses of air. The diameter of the vortex can reach several thousand kilometers. Atmospheric whirlwinds: cyclone, typhoon.

Tornado or a tornado - a very strong vortex, which is a giant funnel or column of clouds. The diameter of such a column above the water can be up to 100 meters, and above the ground up to a kilometer. The height of the tornado reaches 10 kilometers.

Inside the funnel or column, when the air rotates, a zone of rarefied air is formed. The speed of air movement in the funnel has not yet been determined. There is simply no such daredevil who dared to fall into a funnel with instruments. A tornado draws in water, sand, dust, and other objects and carries them over considerable distances. The life span of a tornado ranges from a few minutes to an hour and a half. It is formed in the heat and comes from a cumulonimbus cloud. People have not yet fully determined the mechanism of occurrence of tornadoes.

Optical phenomena in nature

Phenomena associated with the refraction of light.

Mirages.

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 terrestrial objects are more strongly bent and reach the earth's surface, going at a large 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 occurrence of mirages.

Superior mirages are also observed in northern countries when warm southerly winds blow. The upper layers of the atmosphere turn out to be heated, and the lower layers are cooled due to the presence of large masses of 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.

Phenomena related to the dispersion of light

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

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.

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 clearly and sharply outlined and often tinted in red or pinkish, 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 simplest, calmest 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 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 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, in the middle of the 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 strong 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 the blue color of the sky, the ruddy dawn, the 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 the wave properties of light - dispersion, interference, diffraction, polarization, or quantum properties of light. The world is mysterious, but cognizable.