What is a mirage in the desert? Mirage as a natural phenomenon. Types of mirages. What are mirages? See what "Mirage" is in other dictionaries

Classification

Mirages are divided into lower ones, visible under the object, upper ones, above the object, and side ones.

Inferior Mirage

It is observed with a very large vertical temperature gradient (it decreases with height) over an overheated flat surface, often a desert or an asphalt road. The virtual image of the sky creates the illusion of water on the surface. So, the road stretching into the distance on a hot summer day seems wet.

The illusion stems from the way light is refracted through air at different temperatures. Cold air is denser than warm air and therefore has a higher refractive index. This means that as light moves from cold to hot air, it bends upward toward denser air and away from the ground.

A Beginner's Guide to Finding a Mirage

To your eyes, these distorted rays appear to come from the earth, so you perceive a refracted image of the sky on earth. This looks just like the reflection on the surface of a pool of water, which can easily cause confusion. You don't have to go to the desert to see a mirage: they are very common on the roads. In fact, likely locations include anywhere where the ground can absorb a lot of heat. If you've ever walked barefoot on hot asphalt or sand, then you'll know how hot it is!

Superior Mirage

Observed over the cold earth's surface with an inverse temperature distribution (air temperature increases with increasing altitude).

Superior mirages are generally less common than inferior mirages, but are often more stable because cold air does not tend to move upward and warm air downward.

The hot ground heats the air directly above it, creating a sharp temperature gradient in the air - the first ingredient to a good mirage. Make sure you can see in the distance ahead of you. The most spectacular mirages are found in wide open spaces flat earth, as too many hills, dips or bumps will prevent the refracted light from reaching your eyes.

If you see a huge puddle ahead on a rainy day, you'd be better off keeping it clean, as mirages are much more common in dry, sunny weather. To investigate the formation of a mirage, we first need to understand why light is refracted in the air. Areas of air at different temperatures have different refractive indices, as do many other media. The closer the air is to the ground, the hotter it will be, and its refractive index will be lower. We could think of air as many layers of medium with a specific refractive index for each layer, and the refractive index lower for those closer to the ground.

Superficial mirages are most common in polar regions, especially on large, flat ice floes with stable low temperatures. They are also observed at more temperate latitudes, although in these cases they are weaker, less clear and stable. The superior mirage can be upright or inverted, depending on the distance to the true object and the temperature gradient. Often the image looks like a fragmented mosaic of straight and inverted parts.

Thus, when light travels through air, its path is shown in Fig. On the other hand, we must also understand what internal reflection is. If light travels from glass into air at a small angle of incidence, some of the light will be reflected back and the rest will be refracted as it leaves the glass. Since the refractive index of glass is greater than the refractive index of air, the refracted angle is always greater than the angle of incidence. As the angle of incidence becomes larger, the refracted light will get closer and closer to the interface between air and glass.

A normal-sized ship is moving over the horizon. Given a specific state of the atmosphere, its reflection above the horizon appears gigantic.

Superior mirages can have a striking effect due to the curvature of the Earth. If the curvature of the rays is approximately the same as the curvature of the Earth, the light rays can travel great distances, causing the observer to see objects far beyond the horizon. This was observed and documented for the first time in 1596, when a ship under the command of Willem Barentsz, searching for the Northeast Passage, became stuck in the ice on Novaya Zemlya. The crew was forced to wait out the polar night. At the same time, the sunrise after polar night was observed two weeks earlier than expected. In the 20th century, this phenomenon was explained and called the "New Earth Effect".

When it is greater than the critical angle, light will be reflected but not refracted. This phenomenon is called total internal reflection. Figure 4 shows the path of light when a mirage occurs. Suppose there is an oasis, and the light it emits at point A is refracted by air, the light will travel along a curved path. The light is then refracted again by the air. Total internal reflection was discovered a long time ago. Some of its broad applications include optical fiber, single lens reflex camera, and binocular telescope.

In the same way, ships that are actually so far away that they should not be visible above the horizon can appear on the horizon, and even above the horizon, as superior mirages. This may explain some stories of ships or coastal cities flying in the sky, as described by some polar explorers.

Side mirage

The existence of a side mirage is usually not even suspected. This is a reflection from a heated vertical wall.

"What's going on in the ocean?" The strollers were amazed. Is there a castle, an island, a mountain? In fact, a rare reflection of light turned the huge world into a horizon. Author of the column “Count Seismo” about mysterious environmental phenomena. The mission failed because the mountain seemed to block the ships' path. There was no passage, Ross announced his return. A year later, other sailors exposed the mistake: Ross had entered a mirage.

Mountains in the sea, waterfalls in the sky, oases in the desert - deceptive light reflections often mislead people. Recently, a theory has emerged that a mirage led to the sinking of the Titanic. This made the dead iceberg invisible, according to science writer Tim Maltin on TV documentary film. His theory can never be confirmed - mias are fleeting, they quickly disappear.

Such a case is described by one French author. Approaching the fort of the fortress, he noticed that the smooth concrete wall of the fort suddenly shone like a mirror, reflecting the surrounding landscape, soil, and sky. Taking a few more steps, he noticed the same change with the other wall of the fort. It seemed as if the gray, uneven surface was suddenly replaced by a polished one. It was a hot day, and the walls must have become very hot, which was the key to their specularity. It turned out that a mirage is observed whenever the wall is sufficiently heated by the sun's rays. We even managed to photograph this phenomenon.

However, photographer Mila Zinkova recorded a large copy of these illusions. "What's happening?" The Walkers looked at the horizon in front of California, a distant country appeared from somewhere, a mighty mountain towering where the sky used to be. Some tourists believed in the castle.

It soon became clear that this was a castle in the air at best, because the appearance had changed. It became smaller and got holes. Mila Zinkova knew this. "A rare visit," says Fat Morgana off the coast of San Francisco. "Two or three times a year," a phenomenon known as the "Morgana Fairy" appears on the horizon.

On hot summer days, one should pay attention to the heated walls of large buildings and look for signs of mirage. Without a doubt, with some attention, the number of observed cases of lateral mirage should become more frequent.

Fata Morgana

Complex mirage phenomena with a sharp distortion of the appearance of objects are called Fata Morgana.

Its origins are reflected in the Point Reyes Peninsula, which is generally regarded as a narrow landmark 50 km northwest of San Francisco. On some days, special air masses turn small land into huge fantastic mountains.

As far as California, for example, warm air floats over a cold sea. The eye is deceived: rays of light, which usually disappear in height, collide at the boundary of air masses, like at a mirror. They lean towards spectators on the California coast. Since the light from the peninsula now appears to be coming from above, it appears as if there is a huge mountain range on the horizon, even though there is only a flat peninsula.

Volume mirage

In the mountains, very rarely, under certain conditions, you can see the “distorted self” at a fairly close distance. This phenomenon is explained by the presence of “standing” water vapor in the air.

Notes

Links

// Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional ones). - St. Petersburg. , 1890-1907.

Wikimedia Foundation. 2010.

The effect is the same, fantastic oases are projected into the desert: the light bend ensures that the sky is on the desert floor - the appearance looks like a lake. A similar impression is produced on summer asphalt when the light is projected onto the road. The story of the Flying Dutchman must also be traced to a mirage: by reflecting light on a mass of air, it painted a sailboat in the sky above the sea.

Photographers know places where the chances of spectacular mias are good: in Alaska, for example, in Finland or in the Strait of Messina from Sicily. From there the phenomenon will also have its name. The Italians explained mysterious phenomena before Sicily the magical tale of Morgana from the Arthurian saga.

Synonyms:

See what "Mirage" is in other dictionaries:

- (in Italy Fata Morgana, in Russia Haze) optical phenomenon, consisting in the fact that objects located outside the horizon become visible, and those located within it appear enlarged or doubled. It is observed in hot and cold... ... Dictionary of foreign words of the Russian language

Meanwhile, the phenomenon can be scientifically explained, but his passion has preserved him, as the photograph from San Francisco convincingly proves. In the midst of high temperatures, from a distance we see what appear to be puddles of water, where they may even come to reflect other cars, buildings or other objects. But when we get closer, they disappear. This is an optical effect called mirage.

In fact, we are so accustomed to mirages that we often don't know why they happen, or their possible safety implications. traffic. Light is a type of electromagnetic wave. When it is broadcast, it travels in all directions. This is the image that we all have of circular concentric-spherical waves, in fact - starting from the radio antenna. These spheres are called wave fronts.

Cm … Synonym dictionary

MIRAGE, mirage, husband. (French mirage). 1. An optical phenomenon in a clear, calm atmosphere with different heating levels of its individual layers, consisting in the fact that invisible objects located beyond the horizon are reflected in a refracted form in the air.... ... Dictionary Ushakova

- (French mirage), an optical phenomenon in the atmosphere in which, in addition to (or instead of) objects in their true position, their imaginary images are also visible. Mirage is explained by the bending of light rays coming from an object in unequally heated and... ... Modern encyclopedia

Once it is emitted, each point on the wave front normally moves in a straight line and at a constant speed. This is what leads to the gradual expansion of the wave front. The path of each point on the wave front is what we call a ray of light.

But what happens when conditions are not normal? For example, if there is an obstacle in its propagation of light, such as an atom. In this case, the atom absorbs light and returns it to be released a little later, just a millionth of a second. Every time light finds an atom, it accumulates a certain delay. In the end, we see that the light is coming a little slower than usual.

Fata Morgana, Looming, is an optical phenomenon in which objects located beyond the horizon become visible. M. is explained by the uneven heating of layers of air, as a result of which rays from objects when moving from one ... ... Marine Dictionary

Mirage F1 Purpose: fighter-bomber First flight: December 23, 1966 ... Wikipedia

In conclusion, light will slow down the greater the number of atoms in the medium through which it travels. For example, when light hits water, it loses about 25% of its speed. Now sometimes light passes from one medium to another and so the number of atoms it finds changes suddenly. That is, light travels faster in one medium than in another. What happens when two parts of something move at different speeds? Anyone who has swung or driven a track car knows this: something is spinning.

If the wavefront rotates, then its points no longer move in a straight line. That is, light rays follow a curved path as they change their speed. We observed all this as refraction. For example, seeing drinking straw appear to split when viewed through water. If you wear glasses or contact lenses, you can read it thanks to refraction.

The ancient Egyptians believed that a mirage was the ghost of a country that no longer exists. Legend says that every place on Earth has its own soul. Mirages observed in deserts are explained by the fact that hot air acts like a mirror. This phenomenon is quite common - for example, about 160 thousand mirages are observed annually in the Sahara: they can be stable and wandering, vertical and horizontal.

Far Vision Phantom

Well, let's get back to mirages. When the sun shrinks, the pavement accumulates a lot of heat, which is transferred to the nearby air. If each particle takes up more space, that means there will be less air per cubic meter. In short, hot air is less dense than cold air, meaning there will be fewer atoms in the same space that impede the passage of light. The resulting difference in temperature causes light to travel faster near the ground than at altitude. As we said, this change in speed forces the light in a curved direction, in this case upward.

On May 8, 2006, thousands of tourists and local residents observed a mirage that lasted for four hours at Penglai east coast China on Sunday. The fogs created an image of the city, with modern high-rise buildings, wide city streets and noisy cars.

It rained for two days in the city of Penglai before this rare weather event occurred.

Therefore, the light, which originally had a path from top to bottom, which would otherwise end up crashing on the asphalt, rises again and reaches our eyes. This light appears to come from the ground, and it causes us to see reflections on the floor of other objects that are actually higher. If there is no object, then we see a reflection of the sky, so we mix the bluish tone with puddles of water.

As a rule, the temperature difference is not very pronounced, the angle that light can rotate is not very large. Consequently, mirages can only be seen from afar. When we get closer they disappear. Thanks to this, the risk of a mirage hiding obstacles on the road is usually minimal.

It is almost impossible to study mirages, since they do not appear on order and are always original and unpredictable. According to scientists, the atmosphere is like a layered, airy cake, which consists of layers with different temperatures. And the greater the temperature difference, the more the path of the light beam is bent. In this case, it is as if a giant airy lens is formed, which moves all the time. In addition, the observed object and the person himself are inside this air lens. Therefore, the observer sees the image distorted. The more complex the shape of the atmospheric lenses, the more bizarre the mirage.

But in very hot conditions and depending on the slope of the road, there may be closer mirages. If we encounter this spectacular phenomenon, extreme caution must be exercised. First, thinking can make us think that there are no obstacles in the way, forcing us to make a dangerous maneuver unnecessarily.

Conversely, it is possible that a mirage does not allow us to see a real obstacle on the road. The closer the mirage, the shorter the reaction distance we have, and so it is advisable to soften the speed so that we can stop at a distance where we can actually see the road.

Atmospheric mirages divided into three classes: lower or lake; upper(they appear directly in the sky) or distant vision mirages; lateral mirages.
A more complex type of mirage is called " Fata Morgana". No explanation has yet been found for it. The aurora borealis, werewolf mirages, and the “Flying Dutchmen” are usually classified as types of mirages.

Lower (lake) mirage

Inferior mirages are quite common. For example, water seen on desert sand or hot asphalt is a mirage of the sky above the hot sand or asphalt. Airplane landings in movies or car races on television are often filmed very close to the surface of hot asphalt. Then below the car or plane you can see their mirror image (inferior mirage), as well as the mirage of the sky. By the same principle, if you look at an object, for example, along a wall heated by the sun, then you can almost always see a mirage of the object next to the wall.

If on a hot summer day you stand on the railway track or a hill above it, when the sun is slightly to the side or to the side and slightly in front of the railway track, then you can see how the rails two or three kilometers away from us seem to be plunging into a sparkling lake, as if the tracks were flooded flood. Let's try to get closer to the "lake" - it will move away, and no matter how much we walk towards it, it will invariably be 2-3 kilometers away from us.

Such “lake” mirages drove desert travelers, languishing from heat and thirst, to despair. They also saw the coveted water 2-3 kilometers away, they wandered towards it with all their strength, but the water receded and then seemed to dissolve in the air.

In the photo, the sailboat almost disappears into the lower mirage. Only the sail is visible.

Lighthouse Isokari

The lower mirage and the ship's mirage.

Superior mirages (distance vision mirages)

This type of mirages is no more complex in origin than “lake” ones, but more diverse. They are usually called "distant vision mirages".

Residents Cote d'Azur France on a clear morning has been seen more than once on the horizon Mediterranean Sea, where the water merges with the sky, the chain of Corsican mountains rises from the sea, about two hundred kilometers from the Cote d'Azur.

In the same case, if this happens in the desert itself, the surface of which and the adjacent layers of air are heated by the sun, the air pressure at the top may turn out to be high, the rays will begin to bend in the other direction. And then curious phenomena will occur with those rays that, having reflected from the object, should have immediately buried themselves in the ground. But no, they will turn upward and, having passed perigee somewhere near the surface itself, will go into it.

A typical example is given in Aristotle's Meteorology: residents of Syracuse sometimes saw the coast of continental Italy for several hours, although it was 150 km away. Such phenomena are also caused by the redistribution of warm and cold layers of air. in the direction of the last segment of the path of the light beam.

Boat against a background with a typical superior mirage

On April 20, 1999, an ordinary charterer was practicing in the waters of the southwestern archipelago of Finland.
The vessel took many different forms; sometimes it seemed there were 2 ships, one of which was upside down.

Superior mirage and sailboat.

House on the archipelago with the upper mirage

Side mirages

This type of mirage can occur in cases where layers of air of the same density are located in the atmosphere not horizontally, as usual, but obliquely or even vertically. Such conditions are created in the summer, in the morning shortly after sunrise, on the rocky shores of the sea or lake, when the shore is already illuminated by the Sun, and the surface of the water and the air above it are still cold. Lateral mirages have been repeatedly observed on Lake Geneva. We saw a boat approaching the shore, and next to it exactly the same boat was moving away from the shore. A side mirage can appear near a stone wall of a house heated by the Sun, and even on the side of a heated stove.

Fata Morgana

Fata Morgana is a complex optical phenomenon in the atmosphere, consisting of several forms of mirages, in which distant objects are visible repeatedly and with various distortions. Fata Morgana occurs when several alternating layers of air of varying densities are formed in the lower layers of the atmosphere, capable of producing specular reflections. As a result of reflection, as well as refraction of rays, real-life objects produce several distorted images on the horizon or above it, partially overlapping each other and quickly changing in time, which creates a bizarre picture of Fata Morgana.

The mirage received its name in honor of the fairy-tale heroine Fata Morgana or, translated from Italian, the fairy Morgana. They say that she is the half-sister of King Arthur, the rejected lover of Lancelot, who settled out of grief at the bottom of the sea, in a crystal palace, and since then has been deceiving sailors with ghostly visions.

On April 3, 1900, the defenders of the fortress of Bloemfontein, in England, saw the battle formations of the British army in the sky, and so clearly that they could distinguish the buttons on the red uniforms of the officers. This was taken as a bad omen. Two days later the fortress surrendered.

In 1902, Robert Wood, an American scientist who not without reason earned the nickname “the wizard of the physics laboratory,” photographed two boys peacefully wandering through the waters of the Chesapeake Bay between yachts. Moreover, the height of the boys in the photograph exceeded 3 meters.

One man in 1852, from a distance of 4 km, saw the Strasbourg Bell Tower at a distance, as it seemed to him, of two kilometers. The image was gigantic, as if the bell tower appeared before him enlarged 20 times.

TO Fata Morgana can be attributed to numerous " flying Dutchmen ", which are still seen by sailors.

At 11 a.m. on December 10, 1941, the team of the British transport Vendor, located in the area Maldives, noticed a burning ship on the horizon. "Vendor" went to the rescue of those in distress, but an hour later the burning ship fell on its side and sank. "Vendor" approached the supposed place of the ship's death, but, despite a thorough search, did not find not only any debris, but even stains of fuel oil. At the port of destination, in India, the commander of the Vendor learned that at the very moment when his team observed the tragedy, a cruiser was sinking, attacked by Japanese torpedo bombers near Ceylon. The distance between the ships at that time was 900 km.

Mirage ghosts

A French colonial detachment was crossing the Algerian desert. Ahead, about six kilometers from him, a flock of flamingos walked in single file. But when the birds crossed the border of the mirage, their legs stretched out and separated, instead of two, each had four. Neither give nor take - an Arab horseman in a white robe.

The detachment commander, alarmed, sent a scout to check what kind of people were in the desert. When the soldier himself entered the zone of curvature of the sun's rays, he, of course, figured out who he was dealing with. But he also struck fear into his comrades - the legs of his horse became so long that it seemed that he was sitting on a fantastic monster.

Other visions still baffle us today. The Swedish polar explorer Nordenskiöld has repeatedly observed in the Arctic werewolf mirages:

"One day, a bear, whose approach was expected and which everyone clearly saw, instead of approaching with his usual soft gait, zigzags and sniffing the air, wondering whether foreigners were suitable for him as food, just at the moment of the sniper's sight... spread gigantic wings and flew away in the form of a small green seagull. Another time, during the same sleigh ride, the hunters, being in a tent pitched for rest, heard the cry of a cook fiddling around it: “Bear, A big bear! No, it’s a deer, a very small deer.” At the same moment, a shot rang out from the tent, and the killed “bear-deer” turned out to be a small arctic fox, who paid with his life for the honor of pretending to be a large animal for a few moments".

It is also reliably known about mirages-ghosts. This is how British meteorologist Caroline Botley describes this effect.

Mirages lead to victims, but the physical explanation of the phenomenon of mirages does not in the least alleviate the fate of travelers misled by the ephemeral oasis. In order to protect people brought into the desert from the risk of getting lost and dying of thirst, special maps are drawn up marking the places where mirages are usually observed. These guides indicate where wells can be seen, and where palm groves and even mountain ranges can be seen.

Caravans in the Erg-er-Ravi desert in North Africa are especially often victims of mirages. People see oases “with their own eyes” at a distance of 2-3 kilometers, which are actually at least 700 kilometers.