OPTICAL PHENOMENA

OPTICAL PHENOMENA

Phenomena of light in the atmosphere, e.g. rainbow.

Dictionary foreign words, included in the Russian language. - Chudinov A.N., 1910 .

OPTICAL PHENOMENA

Phenomena produced by light.

Explanation of 25,000 foreign words that have come into use in the Russian language, with the meaning of their roots. - Mikhelson A.D., 1865 .

See what “OPTICAL PHENOMENA” is in other dictionaries:

Optical phenomena and their signs- Nouns ZARNI/CA, vspo/lokh, obsolete. spo/loh. An optical phenomenon that is an instantaneous flash of light in the sky at night or in the evening, which is a reflection of a distant thunderstorm. ZARYA/, dawn/t, trad. poet. Avro/ra,… … Dictionary of Russian synonyms

Nonlinear optical phenomena observed in pulsed and time-modulated electrical fields. mag. waves Most N. n. O. I. due to the inertia of the medium, both the inertia of the local nonlinear response and the inertia of the response... ... Physical encyclopedia

Intensively developed in the 1980s and 90s. the new generation will figure it out. technology (computers) based on the use of optical radiation as a carrier of information... Physical encyclopedia

Gas discharge phenomena, similar to electrical discharges in gas, occurring in air or other gases under the influence of powerful light (laser) fields... Physical encyclopedia

Optical system (eng. optical system) a set of optical elements (refractive, reflective, diffraction, etc.), created for a specific formation of beams of light rays (in classical optics), radio waves (in radio optics), ... ... Wikipedia

Not to be confused with the term "Isomerism of atomic nuclei". Isomerism (from izos equal and meros share, part of the Greek, compare iso), the existence of compounds (mainly organic) identical in elemental composition and molecular weight, but different in ... ... Wikipedia

Classical electrodynamics Magnetic field of a solenoid Electricity Magnetism Electrostatics Coulomb's Law ... Wikipedia

Atmospheric phenomena visible manifestation complex physical and chemical processes occurring in the Earth's atmosphere. Classification Groups of atmospheric phenomena: Hydrometeors - a collection of water droplets or ice particles, ... ... Wikipedia

- (I. vision, pseudoscopy) is the name given to incorrect ideas about the shape, size, color and position in space of objects in the external world that arise under the influence of visual impressions. For reasons that cause them, I. vision can be divided ... Encyclopedic Dictionary F. Brockhaus and I.A. Ephron

The emergence of sound (acoustic) waves in media under the influence of optical radiation. F. I. may be associated with inverse piezoelectric. effect in crystals and piezoceramics (see PIEZOELECTRICS, PHOTOELASTICITY), electrostrictive effect, ... ... Physical encyclopedia

Books

• Atmosphere. Meteorology generally understood, Camille Flammarion. Bookstore of P.V. Lukovnikov, St. Petersburg, 1900. Owner's binding. The condition is good. The cover has some wear and some loss of the spine. This edition...
• Optical methods in chemistry, biology and medicine. Monograph, Moryakhina Valeria Sergeevna. The most common ones are considered modern methods spectral analysis, which are based on the absorption of light and the emission of fluorescence. The methods outlined in the monograph are often...

Many people like funny pictures that trick their visual perception. But did you know that nature also knows how to create optical illusions? Moreover, they look an order of magnitude more impressive than those made by humans. These include dozens of natural phenomena and formations, both rare and quite common. Northern lights, halo, green ray, lenticular clouds are just a small part of them. Here are 25 stunning optical illusions created by nature.

Every year in February, the water streams turn fiery orange.

This beautiful and at the same time frightening waterfall is located in the central part of Yosemite National Park. It is called Horsetail Fall (translated as “horse tail”). Every year for 4–5 February days tourists can see a rare phenomenon - the rays of the setting sun are reflected in the falling streams of water. At these moments, the waterfall turns fiery orange. It seems that hot lava is flowing from the top of the mountain, but this is just an optical illusion.

The Horse's Tail waterfall consists of two cascading streams, its total height reaches 650 meters.

Real Sun and two false ones

If the Sun is low above the horizon and there are microscopic ice crystals in the atmosphere, observers may notice several bright rainbow spots to the right and left of the Sun. These bizarre halos faithfully follow our luminary across the sky, no matter which direction it is directed.

In principle, this atmospheric phenomenon is considered quite common, but it is difficult to notice the effect.

This is interesting: On rare occasions, when sunlight passes through cirrus clouds at the right angle, these two spots become as bright as the Sun itself.

The effect is best observed in the early morning or late evening in polar regions.

Fata Morgana - a rare optical illusion

Fata Morgana is a complex optical atmospheric phenomenon. It is observed extremely rarely. In fact, Fata Morgana “consists” of several forms of mirages, due to which distant objects are distorted and “split into two” for the observer.

It is known that Fata Morgana occurs when several alternating layers of air with different densities are formed in the lower layer of the atmosphere (usually due to temperature differences). Under certain conditions they give specular reflections.

Due to the reflection and refraction of light rays, real-life objects can create several distorted images on the horizon or even above it, which partially overlap each other and rapidly change over time, thereby creating a striking picture of Fata Morgana.

Column of light emanating from the sun descending below the horizon

We become witnesses of light (or solar) pillars quite often. This is the name of a common type of halo. This optical effect appears as a vertical stripe of light that extends from the sun at sunset or sunrise. A column of light can be observed when light in the atmosphere is reflected from the surface of tiny ice crystals, shaped like ice plates or miniature rods with a hexagonal cross-section. Crystals of this shape most often form in high cirrostratus clouds. But if the air temperature is low enough, they can appear in less time. high layers atmosphere. We think there is no need to explain why light pillars are most often observed in winter.

Under certain conditions, a shadow can look like a ghost

When there is thick fog outside, you can observe an interesting optical phenomenon - the so-called Brocken ghost. To do this, you just need to turn your back to the main light source. The observer will be able to see own shadow lying on the fog (or cloud if you are in a mountainous area).

This is interesting: If the light source, as well as the object on which the shadow is cast, are static, it will repeat any human movement. But the shadow will appear completely differently on a moving “surface” (for example, on fog). In such conditions, it can fluctuate, creating the illusion that a dark, foggy silhouette is moving. It seems that this is not a shadow belonging to the observer, but a real ghost.

Atlantic Road

It seems like this bridge is not completed

There are probably no more scenic highways in the world than the Atlantic Road, located in the Norwegian county of Møre og Romsdal. A unique highway runs through the northern coast Atlantic Ocean and includes as many as 12 bridges connecting individual islands with road surfaces.

The most amazing place on the Atlantic Road is the Storseisundet Bridge. From a certain angle, it may seem that it is not completed, and all the passing cars, going up, approach the cliff, and then fall down.

The total length of this bridge, opened in 1989, is 8.3 kilometers.

In 2005, the Atlantic Road was named Norway's "Build of the Century". And journalists from the British publication The Guardian awarded it the title of the best tourist route in this northern country.

Moon illusion

The Moon appears to be large when located above the horizon.

When the full Moon is low on the horizon, it is visually much larger than when it is high in the sky. This phenomenon seriously puzzles thousands of inquisitive minds trying to find some reasonable explanation for it. But in fact, this is an ordinary illusion.

The simplest way to confirm the illusory nature of this effect is to hold it in outstretched arm a small round object (for example, a coin). When you compare the size of this object with the “huge” Moon on the horizon and the “tiny” Moon in the sky, you will be surprised to realize that its relative size does not undergo any change. You can also roll a piece of paper into the shape of a tube and look through the hole formed solely at the Moon, without any surrounding objects. Again, the illusion will disappear.

This is interesting: Most scientists, when explaining the Moon illusion, refer to the theory of “relative size”. It is known that visual perception of size visible to humans of an object is determined by the dimensions of other objects observed by it at the same time. When the Moon is low above the horizon, other objects (houses, trees, etc.) come into a person’s field of vision. Against their background, our night star seems larger than in reality.

cloud shadows

Cloud shadows look like small islands

On a sunny day, from a high altitude, it is very interesting to observe the shadows cast by clouds on the surface of our planet. They resemble small, constantly moving islands in the ocean. Unfortunately, ground observers will not be able to appreciate all the splendor of this picture.

The atlas moth practically does not fly

The huge atlas moth is found in tropical forests in southern Asia. It is this insect that holds the record for the surface area of ​​its wings (400 square centimeters). In India, this moth is bred to produce silk threads. The gigantic insect produces brown silk that looks like wool.

Because of large sizes Atlas moths fly disgustingly, moving through the air slowly and clumsily. But the unique coloring of their wings helps them camouflage in their natural habitat. Thanks to her, the atlas literally merges with the trees.

It creates the illusion that dew drops are floating in the air

In the morning or after rain, tiny droplets of water can be seen on the spider webs, resembling a necklace. If the web is very thin, the observer may have the illusion that the drops are literally floating in the air. And in the cold season, the web can be covered with frost or frozen dew; this picture looks no less impressive.

Green ray observed after sunset

A short flash of green light, observed an instant before the solar disk appears over the horizon (most often at sea) or at the moment when the sun disappears behind it, is called a green ray.

You can witness this amazing phenomenon if three conditions are met: the horizon must be open (steppe, tundra, sea, mountainous area), the air is clean, and the area of ​​sunset or sunrise is free from clouds.

As a rule, the green beam is visible for no more than 2–3 seconds. To significantly increase the time interval of its observation at the moment of sunset, you need to immediately after the appearance of the green beam begin to quickly run up an earthen embankment or climb the stairs. If the Sun is rising, you need to move in the opposite direction, that is, down.

This is interesting: During one of the flights over South Pole the famous American pilot Richard Byrd saw the green beam for a full 35 minutes! A unique incident occurred at the end of the polar night, when the upper edge of the solar disk first appeared over the horizon and slowly moved along it. It is known that at the poles the solar disk moves almost horizontally: the speed of its vertical rise is very small.

Physicists explain the effect of the green ray by the refraction (that is, refraction) of solar rays when passing through the atmosphere. Interestingly, at the moment of sunset or sunrise, we should see blue or violet rays first. But their wavelength is so short that when passing through the atmosphere they are almost completely scattered and do not reach the earthly observer.

The near-zenith arc looks like an inverted rainbow

Essentially, the near-zenith arc looks like a rainbow turned upside down. To some people, it even resembles a huge multi-colored smiley face in the sky. This phenomenon is formed due to the refraction of sunlight passing through ice crystals of a certain shape floating in the clouds. The arc is concentrated at the zenith parallel to the horizon. The top color of this rainbow is blue, the bottom color is red.

Halo

The glowing ring around the Moon in the night sky is a halo

A halo is one of the most famous optical phenomena, observing which a person can see a luminous ring around a powerful light source.

During the day, a halo appears around the Sun, at night - around the Moon or other sources, for example, street lamps. Exists huge amount varieties of halo (one of them is the illusion of a false Sun mentioned above). Almost all halos are caused by the refraction of light as it passes through ice crystals concentrated in cirrus clouds (located in the upper troposphere). The appearance of the halo is determined by the shape and arrangement of these miniature crystals.

Mountains and other tall objects turn pinkish

Probably every inhabitant of our planet has seen the pink glow. This interesting phenomenon observed at the moment when the Sun sets below the horizon. Then mountains or other vertical objects (for example, multi-story buildings) little time are painted in a soft pink shade.

Crepuscular rays are observed in cloudy weather

Scientists call twilight rays a common optical phenomenon that looks like an alternation of many light and dark stripes in the sky. Moreover, all these bands diverge from the current location of the Sun.

Crepuscular rays are one of the manifestations of the play of light and shadow. We are sure that the air is completely transparent, and the rays of light that pass through it are invisible. But if there are tiny droplets of water or dust particles in the atmosphere, sunlight is scattered. A whitish haze forms in the air. It is almost invisible in clear weather. But in cloudy conditions, particles of dust or water located in the shadow of clouds are less illuminated. Therefore, shaded areas are perceived by observers as dark stripes. Well-lit areas alternating with them, on the contrary, seem to us to be bright stripes of light.

A similar effect is observed when the sun's rays, breaking through cracks into a dark room, form bright light paths, illuminating dust particles floating in the air.

This is interesting: Crepuscular rays are called different countries differently. The Germans use the expression “The sun drinks water,” the Dutch use “The sun stands on legs,” and the British call the twilight rays “Jacob’s ladder” or “ladder of angels.”

Anti-crepuscular rays emanate from a point on the horizon opposite the setting Sun

These rays are observed at the moment of sunset on the eastern side of the sky. They, like the twilight rays, fan out, the only difference between them is their location relative to the celestial body.

It may seem that the anti-twilight rays converge at some point beyond the horizon, but this is only an illusion. In reality, the sun's rays travel strictly in straight lines, but when these lines are projected onto the Earth's spherical atmosphere, arcs are formed. That is, the illusion of their fan-shaped divergence is determined by perspective.

Northern lights in the night sky

The sun is very unstable. Sometimes powerful explosions occur on its surface, after which the smallest particles of solar matter (solar wind) are directed toward the Earth at great speed. It takes them about 30 hours to reach Earth.

The magnetic field of our planet deflects these particles towards the poles, as a result of which extensive magnetic storms begin there. Protons and electrons penetrating the ionosphere from outer space interact with it. The thin layers of the atmosphere begin to glow. The entire sky is painted with colorful dynamically moving patterns: arcs, bizarre lines, crowns and spots.

This is interesting: You can observe the northern lights at high latitudes of each hemisphere (therefore, it would be more correct to call this phenomenon “aurora”). The geography of places where people can see this impressive natural phenomenon expands significantly only during periods of high solar activity. Surprisingly, auroras also occur on other planets of our solar system.

The shapes and colors of the colorful glow of the night sky change rapidly. Interestingly, auroras occur exclusively in altitude intervals from 80 to 100 and from 400 to 1000 kilometers above ground level.

Krushinnitsa - a butterfly with incredibly realistic natural camouflage

In early April, when consistently warm and sunny weather sets in, you can notice a beautiful light speck fluttering from one spring flower to another. This is a butterfly called buckthorn or lemongrass.

The wingspan of the buckthorn is about 6 centimeters, the length of the wings is from 2.7 to 3.3 centimeters. Interestingly, the colors of males and females are different. Males have bright greenish-lemon wings, while females have lighter, almost white wings.

Krushinnitsa has amazingly realistic natural camouflage. It is very difficult to distinguish it from plant leaves.

Magnetic Hill

Cars seem to be rolling uphill under the influence of an unknown force.

There is a hill in Canada where extraordinary things happen. By parking the car near its foot and turning on the neutral gear, you will see that the car begins to roll (without any assistance) upward, that is, towards the rise. Many people explain the amazing phenomenon by the influence of an incredibly powerful magnetic force, causing cars to roll up hills and reach speeds of up to 40 kilometers per hour.

Unfortunately, there is no magnetism or magic here. It's all about an ordinary optical illusion. Due to the features of the terrain, a slight slope (about 2.5 degrees) is perceived by the observer as an upward climb.

The main factor in creating such an illusion, observed in many other places globe, – zero or minimal horizon visibility. If a person does not see it, then it becomes quite difficult to judge the inclination of the surface. Even objects that are in most cases located perpendicular to the ground (for example, trees) can lean in any direction, misleading the observer even more.

Salt deserts

It seems as if all these people are floating in the sky

Salt deserts are found in all corners of the Earth. People in the middle of them have a distorted perception of space due to the lack of any landmarks.

In the photo you can see a dried-up salt lake located in the southern part of the Altiplano plain (Bolivia) and called the Uyuni salt flat. This place is located at an altitude of 3.7 kilometers above sea level, and its total area exceeds 10.5 thousand square kilometers. Uyuni is the largest salt marsh on our planet.

The most common minerals found here are halite and gypsum. And the layer thickness table salt on the surface of the salt marsh in some places it reaches 8 meters. Total salt reserves are estimated at 10 billion tons. On the territory of Uyuni there are several hotels built from salt blocks. Furniture and other interior items are also made from it. And there are notices on the walls of the rooms: the administration politely asks guests not to lick anything. By the way, you can spend the night in such hotels for only 20 dollars.

This is interesting: During the rainy season, Uyuni is covered with a thin layer of water, thanks to which it turns into the largest mirror surface on Earth. In the middle of the endless mirror space, observers get the impression that they are soaring in the sky or even on another planet.

Wave

Sand dunes turned to stone

The Wave is a naturally formed gallery of sand and rock, located on the border of the American states of Utah and Arizona. Popular national parks in the United States are nearby, so the Wave attracts hundreds of thousands of tourists every year.

Scientists claim that these unique rock formations have been formed for more than one million years: sand dunes under the influence of conditions environment gradually hardened. And the wind and rain, which acted on these formations for a long time, polished their shapes and gave them such an unusual appearance.

Apache Indian Head

It's hard to believe that this rock formation was formed without human intervention

This natural rock formation in France vividly illustrates our ability to recognize familiar shapes, such as human faces, in surrounding objects. Scientists have recently discovered that we even have a special part of the brain responsible for recognizing faces. It is interesting that human visual perception is structured in such a way that any objects similar in outline to faces are noticed by us faster than other visual stimuli.

There are hundreds of natural formations in the world that exploit this human ability. But you must agree: the mountain range in the shape of the head of an Apache Indian is probably the most striking of them all. By the way, tourists who had the opportunity to see this unusual rock formation located in the French Alps cannot believe that it was formed without human intervention.‎

An Indian in a traditional headdress and with headphones in his ears - where else can you see this?

The Guardian of the Wasteland (another name is “Indian Head”) is a unique geoformation located near the Canadian city of Madisen Hat (southeastern part of Alberta). When looking at it from a great height, it becomes obvious that the terrain forms the outline of the head of a local aborigine in a traditional Indian headdress, looking intently somewhere to the west. Moreover, this Indian also listens to modern headphones.

In fact, what resembles a headphone wire is the path leading to the oil rig, and the liner is the well itself. The height of the “Indian head” is 255 meters, width is 225 meters. For comparison, the height of the famous bas-relief at Mount Rushmore, on which the faces of four American presidents are carved, is only 18 meters.

The Wasteland Guardian was formed naturally through the weathering and erosion of soft, clay-rich soil. According to scientists, the age of this geoformation does not exceed 800 years.

Lenticular clouds

Lenticular clouds look like huge UFOs

The unique feature of lenticular clouds is that no matter how strong the wind is, they remain motionless. Air currents sweeping over the earth's surface flow around obstacles, resulting in the formation of air waves. Lenticular clouds form at their edges. In their lower part there is a continuous process of condensation of water vapor rising from the surface of the earth. Therefore, lenticular clouds do not change their position. They just hang in the sky in one place.

Lenticular clouds most often form on the leeward side of mountain ranges or over individual peaks at altitudes from 2 to 15 kilometers. In most cases, their appearance signals an approaching atmospheric front.

This is interesting: Because unusual shape and absolute stillness, people often mistake lenticular clouds for UFOs.

Clouds with thunderstorm

Such a sight inspires fear, you must agree!

Horrifying clouds with thunderstorms are observed quite often in flat areas. They descend very low to the ground. There is a feeling that if you climb to the roof of the building, you can reach them with your hand. And sometimes it may seem that such clouds are even in contact with the surface of the earth.

A thunderstorm (another name is a squall gate) is visually similar to a tornado. Fortunately, in comparison with this natural phenomenon, it is not so dangerous. A thunderstorm is simply a low, horizontally oriented area of ​​thundercloud. It is formed in its front part during rapid movement. And the squall gate acquires an even and smooth shape under conditions of active upward air movement. Such clouds, as a rule, form during the warm period of the year (from mid-spring to mid-autumn). Interestingly, the lifespan of thunderstorms is very short - from 30 minutes to 3 hours.

Agree, many of the phenomena listed above seem truly magical, even though their mechanisms can be easily explained with scientific point vision. Nature, without the slightest human participation, creates amazing optical illusions that amaze the imagination of even researchers who have seen a lot of things in their lifetime. How can one not admire its greatness and power?

In ancient times, mirages, auroras, mysterious glowing lights and ball lightning frightened superstitious people. Today scientists have managed to uncover the secrets of these mysterious phenomena, understand the nature of their occurrence.

Phenomena associated with the reflection of sunlight

Everyone has seen many times how, after rain or near a stormy water stream, a colored bridge appears in the sky - a rainbow. The rainbow owes its colors to the sun's rays and droplets of moisture suspended in the air. When light hits a drop of water, it appears to split into different colors. In most cases, the drop reflects light only once, but sometimes light bounces off the drop twice. Then two rainbows flash in the sky.

Many desert travelers have witnessed another atmospheric phenomenon, the mirage. In the middle of the desert, an oasis with palm trees appeared, a caravan or ship moving across the sky. This happens when hot air above the surface rises. Its density begins to increase with height. Then the image of a distant object can be seen above its actual position.

In frosty weather, pronounced halo rings appear around the Sun and Lupus. They form when light is reflected from ice crystals that are quite high in the atmosphere, such as cirrus clouds. WITH inside the halo may have a bright color and a reddish tint. Ice crystals sometimes reflect sunlight so bizarrely that other illusions appear in the sky: two suns, vertical pillars of light or solar arcs. Around the Sun and Moon, halos sometimes form - crowns. The crowns look like several rings nested inside each other. They occur in altocumulus and altostratus clouds. A crown of color may appear around a shadow cast, for example, by an airplane on underlying clouds.

Phenomena related to electricity

Tiny particles from space often fall into the upper layers. Due to their collision with particles of gases and dust, the aurora appears - the glow of the sky with flashes in the polar latitudes of the Northern and Southern Hemispheres. Shapes and colors aurora varied. Its duration can range from tens of minutes to several days.

Drops and ice crystals moving in cumulonimbus clouds accumulate electrical charges. This causes a giant spark to appear between the clouds or between the cloud and the ground - lightning, which is accompanied by thunder. The accumulation of electricity in the atmosphere sometimes forms glowing ball with a diameter of tens of centimeters, this is ball lightning. It moves with the movement of air and can explode upon contact with individual objects, especially metal ones. Having penetrated the house, ball lightning quickly moves through the room, leaving behind scorched areas. Ball lightning may cause serious burns and death. An exact explanation of the nature of this phenomenon does not yet exist.

Another phenomenon associated with the electric glow of the atmosphere is St. Elmo's fire. This glow can be observed in thunderstorms on high tower spiers, as well as around ship masts. It frightened superstitious sailors, who considered it a bad sign.

The atmosphere is a turbid, optically inhomogeneous medium. Optical phenomena are the result of reflection, refraction and diffraction of light rays in the atmosphere.

Depending on the causes of occurrence, all optical phenomena are divided into four groups:

1) phenomena caused by the scattering of light in the atmosphere (twilight, dawn);

2) phenomena caused by the refraction of light rays in the atmosphere (refraction) - mirages, twinkling of stars, etc.;

3) phenomena caused by the refraction and reflection of light rays on drops and crystals of clouds (rainbow, halo);

4) phenomena caused by the diffraction of light in clouds and fog - crowns, glory.

Twilight caused by the scattering of sunlight in the atmosphere. Twilight is the transition period from day to night (evening twilight) and from night to day (morning twilight). Evening twilight begins from the moment the sun sets and until complete darkness sets in, morning twilight - vice versa.

The duration of twilight is determined by the angle between the direction of the apparent daily movement of the Sun and the horizon; Thus, the duration of twilight depends on geographic latitude: the closer to the equator, the shorter the twilight.

There are three periods of twilight:

1) civil twilight (the sun's descent below the horizon does not exceed 6°) – light;

2) navigation (immersion of the Sun below the horizon up to 12 o) - visibility conditions are greatly deteriorated;

3) astronomical (immersion of the Sun under the horizon up to 18 o) - y earth's surface It’s already dark, but the dawn is still visible in the sky.

Zarya - a set of colorful light phenomena in the atmosphere observed before sunrise or during sunset. The variety of colors of dawn depends on the position of the Sun relative to the horizon and on the state of the atmosphere.

The color of the sky is determined by the scattered visible rays of the Sun. In a clean and dry atmosphere, light scattering occurs according to Rayleigh's law. Blue rays are scattered about 16 times more strongly than red ones, so the color of the sky (scattered sunlight) is blue, and the color of the Sun and its rays at the horizon is red, because. In this case, light travels a longer path in the atmosphere.

Large particles in the atmosphere (droplets, dust particles, etc.) scatter light neutrally, which is why clouds and fog are white. With high humidity and dust, the entire sky becomes not blue, but whitish. Consequently, by the degree of blueness of the sky one can judge the purity of the air and the nature of the air masses.

Atmospheric refraction – atmospheric phenomena associated with the refraction of light rays. Refraction is caused by: the twinkling of stars, the flattening of the visible disk of the Sun and Moon at the horizon, an increase in the length of the day by several minutes, as well as mirages. A mirage is a visible imaginary image on the horizon, above the horizon or below the horizon, caused by a sharp violation of the density of air layers. There are lower, upper, and lateral mirages. Moving mirages – “Fata Morgana” – are rarely observed.

Rainbow - this is a light arc, painted in all the colors of the spectrum, against the background of a cloud illuminated by the Sun, from which raindrops fall. The outer edge of the arc is red, the inner edge is purple. If the Sun is low above the horizon, then we see only half of the circle. When the Sun is high, the arc becomes smaller, because the center of the circle falls below the horizon. When the Sun's altitude is greater than 42°, the rainbow is not visible. From an airplane you can see a rainbow in an almost complete circle.

A rainbow is formed by the refraction and reflection of sunlight in water droplets. The brightness and width of the rainbow depends on the size of the droplets. Large droplets produce a smaller but brighter rainbow. With small drops it is almost white.

Halo - these are circles or arcs around the Sun and Moon that appear in upper-level ice clouds (most often in cirrostratus).

Crowns - light, slightly colored rings around the Sun and Moon, appearing in water and ice clouds of the upper and middle tiers, due to the diffraction of light.

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

Basic Concepts

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

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

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

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

Unusual processes in the atmosphere

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

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

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

Let's take a closer look at them.

Halo around the Sun

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

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

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

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

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

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

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

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

Halo around the Moon and other types

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

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

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

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

False Sun

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

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

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

Rainbow

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

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

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

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

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

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

aurora

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

Mirage

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

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

Brocken Ghost

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

St. Elmo's Fire

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

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

Designs in optics

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

All optical devices can be divided into two types:

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

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

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

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

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

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