How does a mirage appear?
If you see a hatch in the sky, maybe this is not a glitch. Let's talk about the mirages and how they appear. This optical illusion arises from the reflection of light from the boundary of air layers, one of which is much colder than the other. Especially often mirages can be observed in deserts and polar regions. You can immediately clarify that some mirages do not see everything, and this is imagination or hallucinations.
A well-known image: heat-exhausted people, lost in the desert, suddenly see a strip of water in front and rush to dive into it, but fall on hot sand. And yet they did see water. Was it a hallucination? No, it was only a distorted reality - a phenomenon called mirage.
A similar phenomenon can also be observed in air if the temperature changes dramatically when going from one air layer to another. For example, in summer, the air layer adjacent to the road surface heated by the sun may be 10 ° C hotter than a few centimeters above it. Temperature differences determine the difference in the refractive index of air and affect the light passing through the air. Rays emanating from a distant object, while deflected upward. As a result, we can see a shiny surface in which distant objects are reflected.
For example, a distant tree appears floating upside down on the water of a nonexistent lake. This is the so-called lower mirage. The visible water in this case turns out to be really only a reflection of the sky, and an inverted tree is an image of a real tree growing in the distance.
Corsica in the sky
In the open sea sailing ship. But people on the shore saw him before he came from over the horizon. Again, this is not a collective hallucination, but a real image resulting from the upper mirage.
In the polar regions and in the open sea, the lower layers of the atmosphere can be much colder than those immediately above them. The border between these layers refracts the light, deflecting it downwards. As a result, observers see an object in the sky, actually located far beyond the horizon.
Residents of Nice often observe this phenomenon. From the beaches around this French city in the sky you can sometimes see Corsica - or, more precisely, the image of the island created by a mirage.
A strip of water across the road, moving away whenever the car approaches it. A large steamship hanging in the sky above Lake Michigan masts down. Dark medieval castles soaring above the sea. What is common between these pictures? These are mirages. They are created as a result of a complex play of air and light. Mirages can be as simple as a strip of water across a highway 100 meters in front of the car. But there are mirages very complex in design. Description of the mirage In 1643, the Italian priest Angelucci described an incredible and wonderful vision that came to him during his voyage. Here is what he tells. At first, his gaze did not seem anything but a calm sea smoothness, stretching to the very horizon. Then a dark mountain range appeared on the horizon.In front of the mountain peaks from the sea high dirty white columns began to grow. Gradually, the columns began to bend and turned into Romanesque arches. At the end of this grand spectacle on the arches silhouettes of towers and walls of a mighty fortress appeared.
This mirage Italians call the veil - Morgana (fata morgana, from the Italian fata - "miracle"). There are old Celtic legends about King Arthur and his knights. Arthur had a sister, the sorceress Morgan le Fay. She was able to create locks, soaring in the air. Air is indeed the magical component of the mirage. From physics, we know that at the border of two media the rays of light refract, that is, change their direction. These two environments in the atmosphere are layers of air.
In hot weather, the layer of air adjacent to the hot earth has a higher temperature than the upper layers of the atmosphere. The higher the air temperature, the lower its density. This is the whole trick. More dense air refracts more light than less dense. That is, a ray of light, crossing the border of warm and cold air, is refracted. Now consider the course of the rays falling from the sky. These rays are mostly colored blue - the color of the sky. A part of the rays, without being refracted, reaches the eye of the observer and forms a picture of the sky.The other part is refracted and falls to the ground in front of the observer. Reflected from the ground, these reflected rays, in turn, also fall into the eye of the observer. But these are all the same rays of blue sky. Therefore, car passengers see ahead of the blue area. The surface layer of air on a hot day constantly fluctuates, as a result an impression arises, and this creates the illusion of the water surface.
Mirages are not a game of imagination. They were even filmed on film. Rays of light are refracted when crossing the border of warm and cold air. A mirage can also occur in the reverse situation. Such a situation often develops above the surface of the sea. Rays of light reflected from the sea surface, are refracted at the boundary of cold and warm air and go to the sky, and reflected from it, they return to the ground again. That is why a ship sailing beyond the horizon may suddenly appear in the sky. A huge "Flying Dutchman", floating among the clouds. Mirages can occur in a storm and calm. A picture similar to that which the Reverend Father Angelucci saw was a picture of the calm surface of the sea, reflected in the sky from different angles and returned to the ground.capricious images of columns and castles. Ghostly castles in the air and other mirages were filmed on film. Shot successfully. This proves that the mirage is not a game of imagination. A thirsty traveler who sees an oasis with a well in the desert is not hallucinating. He sees a real oasis, which, reflected in the hot sky of the desert, returned to earth in the form of a ghost.
Mirage (fr. Mirage - lit. visibility) is an optical phenomenon in the atmosphere: the refraction of light streams at the interface between layers of air that are sharply different in density and temperature. For the observer, such a phenomenon consists in the fact that, together with a really visible distant object (or part of the sky), its reflection in the atmosphere is also visible.
Mirages are divided into lower, visible below the object, upper, visible above the object, and side.
Mirage over the sea, Indonesia.
Observed with a large vertical temperature gradient (falling with height) above a superheated flat surface, often desert or asphalt road. The imaginary image of the sky creates the illusion of water on the surface. So, on a departing road on a hot summer day, a puddle is seen.
Beyond the horizon, a ship of normal size moves. With a specific state of the atmosphere, its reflection above the horizon seems gigantic.
Observed over a cold earth's surface with an inverse temperature distribution (air temperature rises with increasing altitude).
Upper mirages occur as a whole less frequently than lower ones, but more often they are more stable, because cold air does not tend to move upwards, and warm air does not tend to move downward.
The upper mirages are most common in the polar regions, especially on large, flat ice floes with a stable low temperature. Such conditions may occur over Greenland and in the Iceland region. Perhaps due to this effect, called hillingar (from Icelandic hillingar), the first settlers of Iceland learned about the existence of Greenland.
The upper mirages are also observed in more moderate latitudes, although in these cases they are weaker, less clear and stable. The top mirage can be straight or inverted, depending on the distance to the true object and the temperature gradient. Often the image looks like a fragmentary mosaic of straight and inverted parts.
The upper mirages can have a striking effect due to the curvature of the Earth.If the bending of the rays is about the same as the curvature of the Earth, the rays of light can move over long distances, as a result of which the observer sees objects that are far beyond the horizon. This was observed and documented for the first time in 1596, when a ship under the command of Willem Barents in search of the Northeast Passage was stuck in the ice on Novaya Zemlya. The crew was forced to wait out the polar night. At the same time, the rise of the sun after the polar night was observed two weeks earlier than expected. In the 20th century, this phenomenon was explained, and received the name "The Effect of the New Earth".
In the same way, ships that are in fact so far away that they should not be visible above the horizon can appear on the horizon, and even above the horizon, like upper mirages. This may explain some stories about the flights of ships or coastal cities in the sky, as described by some polar explorers.
Side mirages can occur as a reflection from a heated sheer wall. The case is described when a flat concrete wall of the fortress suddenly shone like a mirror, reflecting surrounding objects. On a hot day, a mirage was observed whenever the wall was sufficiently heated by the sun.
The complex phenomena of a mirage with a sharp distortion of the type of objects are called Fata Morgana. Fata Morgana (Italian. Morgana fata - Morgana fairy, according to legend, living on the seabed and deceiving travelers with ghostly visions) - a rarely occurring complex optical phenomenon in the atmosphere, consisting of several forms of mirages, in which distant objects are seen repeatedly and with various distortions .
Fata-morgana occurs in cases where several alternating layers of air of different density are formed in the lower layers of the atmosphere (usually due to temperature differences) that can give specular reflections. As a result of reflection, as well as refraction of rays, real-life objects on the horizon or above it provide several distorted images that overlap partially with each other and rapidly vary in time, which creates a fanciful picture of the veil.
In the mountains, very rarely, under the confluence of certain conditions, one can see a “distorted self” at a fairly close distance. This phenomenon is explained by the presence of "standing" water vapor in the air.
Phantom far vision
One of the best examples of such phantoms is the Flying Dutchman. According to sea myths, the captain of the ghost ship forever condemned to wander across the expanses of the sea, without approaching anywhere. Sailors from the meeting with the mystical ship never expected anything good - it always signified misfortune and shipwreck.
Almost all the stories about him sounded about the same - the ghost ship sailed directly at them, did not respond to signals and shouts, and then suddenly disappeared in the fog. In fact, the crew of the ship saw in front of them a projection of the ships that were at that time at a great distance from them.
A distant vision mirage appears when the earth's surface heats the air masses, after which they go up and cool. If at the top above a layer of cold air masses for some reason or other it turns out to be warmer (for example, it was brought here by the wind from the south) and at the same time a very rarefied layer, and the temperature difference between them will be quite large, then refraction will occur. Light rays that are reflected from objects that are located on the earth's surface, will make an arc and go back down, but not to their immediate source. They find themselves in dozens, and sometimes hundreds of kilometers away.
A remarkable and documented optical phenomenon is considered, among other things, the so-called Brokensky ghost. It is also called the mountain ghost, which in reality is nothing more than the shadow of the observer on the surface of the clouds (fog) in the direction opposite to the sun. The shadow may seem to the observer to be very large and sometimes surrounded by colored rings; it can also “move” (sometimes completely unexpectedly) due to the movement of the cloud layer and density fluctuations in the cloud. Brokenskogo ghost can be seen in the mountains during fog or clouds, or even from the aircraft. Fame - this phenomenon is due to the peak of Brocken, in the mountains in Germany. Constant fog and the availability of low altitudes allow you to see it very often.
Another very surprising optical phenomenon is refraction, which occurs, on the contrary, in high latitudes, in the polar regions. Refraction is nothing but the refraction of sunlight in the atmosphere itself. This phenomenon allows us to see our daylight even when it has gone beyond the horizon. Or vice versa - before dawn.In this case, the refraction of the rays as if raises the image of the sun, and you see the sunrise before its real offensive. The point here is the same: the sun's ray spreads in the air not along a straight line, but along a convex curved line.
And it is quite rare cases of the appearance of the upper and lower mirages at the same time. They are called "Fata Morgana" - named after the fairies Morgana, who, according to legend, lives on the seabed and deceives travelers with ghostly visions. The rays in this case are refracted both in the upper and in the lower layers of air. As a result, you see a picture distorted beyond recognition, taking an ordinary stone as a skyscraper, and a rock as a medieval castle. Fata Morgana can be observed in low latitudes in close proximity to the sea shore.