Are mirages real?

Mirage is a natural phenomenon formed by the refraction of light. This word is also used as an idiom to describe things that are illusory and do not actually exist. In 1987, a movie of the same name was filmed in my country, and there are also bands named after it. Mirages in the desert: In places such as calm seas, rivers, lakes, snowfields, deserts or Gobi, phantoms such as tall buildings, city outlines, and trees may occasionally appear in the air or "underground", which are called mirages. This kind of illusion often appears on the sea in Penglai, Shandong, my country. The ancients attributed it to a mirage belonging to the dragon family, which breathed out its breath to form a towering city outline, hence its name.

Mirages can not only occur at sea and in deserts, but can also occasionally be seen on asphalt roads. Mirage is the result of refraction of light in air layers with different densities in the vertical direction. There are many types of mirage. According to the position of its appearance relative to the original object, it can be divided into superior mirage, inferior mirage and lateral mirage; according to its symmetrical relationship with the original object, it can be divided into positive mirage, lateral mirage and lateral mirage. And reverse mirage; according to color, it can be divided into chromatic mirage and achromatic mirage, etc.

Mirages have two characteristics: first, they appear repeatedly in the same place. For example, mirages often appear over Alaska in the United States; second, they appear at the same time. For example, most mirages in Penglai, my country, appear every year. In May and June, mirages near Chimlensk, Russia, tend to appear in spring, while mirages in Alaska, the United States, generally appear within 20 days after June 20.

Since ancient times, mirages have attracted the attention of the world. In Western mythology, mirages are depicted as the incarnation of the devil and a bad omen of death and misfortune. In ancient my country, mirages were regarded as fairyland. Qin Shihuang and Emperor Wu of Han once led people to Penglai to search for fairyland, and they also sent people to Penglai many times to seek panacea. Modern science has correctly explained most mirages and believes that mirages are virtual images formed by light reflected by objects on the earth and refracted by the atmosphere. The so-called mirage is an optical illusion.

Mirages are closely related to geographical location, geophysical conditions, and meteorological characteristics of those places at specific times. Abnormal distribution of temperature is the meteorological condition that causes most mirages.

Take the formation of summer mirages as an example. In the summer, the sun is blazing in the desert, and the sand is scorched. Because the specific heat of the sand is small, the temperature rises very quickly. The temperature of the lower air near the sand rises very high, while the temperature of the upper air remains very low, thus forming a temperature pattern. Abnormal distribution. Due to thermal expansion and contraction, the density of hot air in the lower layer close to the sand is small and the density of cold air in the upper layer is high. In this way, the refractive index of the air is small in the lower layer and large in the upper layer. When the light reflected from a taller object in the distance is continuously refracted from the denser air in the upper layer into the sparser air in the lower layer, its incident angle gradually increases, and total reflection occurs when it increases to equal the critical angle. At this time, if a person walks backwards If you look at the reflected light, you will see a mirage.

Due to the dark color of the asphalt road surface and its strong absorption capacity under the scorching sunshine in summer, it will also form a distribution pattern above the road surface where the air in the upper layer is cold and dense, while the air in the lower layer is hot and low density. A mirage will form.

The "mirage" that occurs in the desert is the refraction phenomenon that occurs when sunlight encounters air of different densities. In the desert, the sand and rocks are baked by the sun during the day, and the temperature on the surface of the sand layer rises rapidly. Due to the poor heat transfer performance of the air, when there is no wind, the vertical temperature difference over the desert is very significant. It is hot at the bottom and cold at the top. The air density in the upper layer is high and the air density in the lower layer is low. When sunlight passes from a high-density air layer into a low-density air layer, the speed of light changes. After the refraction of light, the oasis in the distance appears in front of people's eyes. This "mirage" phenomenon sometimes appears on the sea or river.

A mirage is an optical illusion, a virtual image formed by the refraction of light reflected by objects on the earth through the atmosphere. Mirage is referred to as mirage. According to the principles of physics, mirage is caused by different air layers having different densities, and light has different refractive index in air with different densities. It is caused by the refraction of light due to the difference in density between the warm air on the sea surface and the cold air at high altitudes. Mirages are closely related to geographical location, geophysical conditions, and meteorological characteristics of those places at specific times. Abnormal distribution of temperature is the meteorological condition that causes most mirages.

Cause

When sailing on calm and windless seas or looking at the seaside, you will often see images of distant ships, islands or city towers reflected in the sky; traveling in the desert People sometimes suddenly discover that there is a lake in the remote desert, with the swaying shadows of the trees on the lakeside, making people yearn for it. But when the strong wind blows, these scenes suddenly disappear. It turns out that this is an illusion, commonly known as a mirage, or simply a mirage. Schematic diagram of mirage

Why does this phenomenon occur? To answer this question, we must first start with the refraction of light.

When light travels in a uniform medium of the same density, the speed of light remains unchanged and it advances in a straight direction. However, when the light enters another medium of different densities obliquely from this medium , the speed of light will change and its direction will also twist. This phenomenon is called refraction.

When you insert a straight rod into the water at an angle, you can see that the underwater part of the rod and the part exposed on the water seem to be broken. This is caused by the refraction of light. Someone has used a device to make the light from When the water is projected onto the interface between water and air, you can see that the light is divided into two parts at this interface: one part is reflected into the water, and the other part is refracted into the air. If you turn the mirror in the water so that the light hitting the interface is more tilted, the refraction of the light in the air will appear more severe. When the light directed toward the interface is as shown in the picture below on the left, all the light is reflected into the water, and there is no more light refracted into the air. This phenomenon is called total reflection.

Air itself is not a uniform medium. Under normal circumstances, its density decreases with increasing height. The higher the height, the smaller the density. When light passes through air layers at different heights, it will always cause some refraction, but we are used to this refraction phenomenon in our daily lives, so we don't think it's anything strange.

In summer, the humidity of seawater is relatively low during the day, especially when cold water flows through the sea surface. The water temperature is lower. The air in the lower layer is affected by the water temperature. The air in the lower layer is affected by the water temperature. It is colder than the air in the upper layer. The abnormal phenomenon of cold rising to warm (normal conditions are warm at the bottom and cool at the top, with an average temperature drop of about 0.6°C for every 100 meters of elevation). The air in the lower layer is already denser due to higher air pressure. Now coupled with the fact that the temperature is lower than that in the upper layer, the density becomes particularly high. Therefore, the difference between the denser air layer at the lower level and the thinner air layer at the upper level is extremely significant.

If there is a ship under our eastern horizon, it will generally not be visible. If the difference between the lower air and the upper air is too great, the light from the ship will first be gradually refracted from the dense air layer into the thin air layer, and will undergo total reflection in the upper layer, and then refract back to the lower dense air layer. ; After such a curved line, and finally put into our eyes, we can see its image. Since human vision always perceives objects as coming from a straight direction, the image of the ship we see is much higher than the actual object, so it is called a mirage.

There is a Miaodao Islands in the Bohai Sea of ??my country. In summer, the sea water temperature is low during the day, and the air density will be significantly different from dense underground to thin. In Penglai County (also called Dengzhou in ancient times) on the south coast of the Bohai Sea ), the phantom of the Temple Island Islands can often be seen. Shen Kuo of the Song Dynasty recorded this in his famous book "Mengxi Bi Tan":

"There are clouds in the sea of ??Dengzhou from time to time, such as palaces and terraces, figures on the battlements, chariots and horses, and crowns. You can see it clearly."

This is the mirage he saw in Penglai. On July 6, 1624 (May 21, the fourth year of Ming Dynasty), a miraculous spectacle occurred on the sea in Dengzhou that lasted for more than eight hours. Yuan Keli, the outgoing governor of Denglai at that time, witnessed the whole process and was emotionally moved. I was very excited. A "Poetry on the Sea City" recorded the grand occasion in detail at that time. The beautiful words can make people who have never seen the Hai City feel like they were there. Coupled with Dong Qichang's calligraphy, it became the East China Sea. 's immortal work. At around 11 o'clock in the morning on May 22, 1933, a mirage was also discovered on Zhucha Island in Qianhai (outside of Jiaozhou Bay), Qingdao. It spread to the whole city and many people went to watch it. In 1975, a mirage lasted for six hours on the sea near Guangdong Province.

Not only can mirages be seen on the sea in summer, they can also sometimes be seen on the river. For example, it appeared on the river near Nantong on August 2, 1934. It was a sweltering day and the weather was extremely hot. In the afternoon, I suddenly noticed towers, city outlines, trees and houses reflected in the sky above the Yangtze River. The entire mirage was more than 20 miles long. About half an hour later, it moved eastward and suddenly disappeared. Then three more mountains appeared, towering into the clouds, with a mountain in the middle that looked like an incense burner. It took another half an hour before they all disappeared.

In the desert, the sand and rocks are scorched by the sun during the day, and the temperature near the sand layer rises very quickly. Since air is not good at heat transfer, when there is no wind, the heat exchange between the upper and lower layers of air is very small, which makes the vertical difference in temperature between hot and cold at the bottom very significant, and leads to the abnormal phenomenon that the air density in the lower layer is smaller than that in the upper layer. In this case, if there is a tree in front of you and it grows in a relatively humid place, then the light projected downward from the treetop will pass from the denser air layer into the less dense air layer. refraction. When the refracted light reaches the hot and thin air layer close to the ground, total reflection occurs. The light is reflected from the less dense air layer near the ground back to the denser air layer above. In this way, through a downward and downward curved light, the image of the tree is sent to people's eyes, and a reflection of the tree appears.

Because the reflection is located below the real object, it is also called a mirage. This kind of reflection can easily give people the illusion of the shadow of trees by the water, thinking that there must be a lake in the distance. Most people who have traveled in the desert have similar experiences. A photographer who shot the film "Climbing Shishapangma" once saw such a mirage while walking on a vast dry grassland. He ran in the direction of the mirage to get some water to cook. meal. When he ran there and saw there was no water source, he realized that he had been fooled by a mirage. This is because dry grass, like sand, can be heated up by the scorching sun, causing the density of the air layer to gradually increase from bottom to top, thus producing a downward mirage.

No matter what kind of mirage, it can only appear in weather conditions with no wind or very weak wind.

When strong winds come together, causing the agitation and mixing of the upper and lower air, the density difference between the upper and lower air is reduced, and there is no abnormal refraction or total reflection of light, then all the illusions disappear immediately.

All in all, this is a very interesting refraction phenomenon.

Information about the best places to watch shows that Changdao is the place where mirages appear most frequently in China, especially after rains in July and August.

Changdao, historically known as Miaodao Islands, also known as Changshan Islands, consists of 32 islands with a land area of ??56 square kilometers, a sea area of ??8,700 square kilometers, and a coastline of 146 kilometers. It is the only island in Shandong Province Haidao County is under the jurisdiction of Yantai City. The county governs 2 towns and 8 townships, with a population of 45,000. The county seat is located on Nanchangshan Island.

Changdao has a continental climate in the eastern Asian monsoon zone, with warm winters and cool summers. The annual average temperature is 11.9°C and the frost-free period is 243 days. The county's forest coverage rate is 53.2%. Its unique location and superior natural conditions make it a must-pass for migratory birds. There are more than 200 species of migratory birds passing through every year, as many as one million. It enjoys the reputation of a "stop" for migratory birds. It has a good reputation and is listed as a national nature reserve.

Changdao is called the Miaodao Islands (called Shamen Island in ancient times) on Chinese territory, or Changdao for short. It is located between the Shandong Peninsula and the Liaodong Peninsula, at the intersection of the Yellow Sea and the Bohai Sea. It is the only island county in Shandong Province.* **It consists of 32 islands with a total area of ??56 square kilometers. The total length of coastline is 146 kilometers and the permanent population is 45,000.

Changdao is a blessed place in China. It has four major myths and folklore figures: "Mazu protects the sea", "Eight Immortals cross the sea", "Zhang Yu cooks the sea" and "Jingwei fills the sea". When you go to Changdao, you can eat hundreds of kinds of seafood, live on a fisherman’s house, tour the island’s shores, buy delicious specialties, and enjoy the folk customs. The mountains of Changdao are “the beauty of Wuling Shili Gallery”, and the sea of ??Changdao is “the beauty of the scenery on both sides of the Li River”. "The East China Sea is blessed with fertile water and fish fertilizer, and the South China Sea is home to auspicious mountains and beautiful fruit fields." And "The Yellow Sea is sailing with silver sails to chase the sun, and the Bohai Sea is sunset and the fishing boats are singing in the evening." This is the most simple, bold, and authentic expression of the Xianjing fishermen. The most vivid portrayal of life.

Changdao is a blessed place in China and has the reputation of "the hometown of Chinese abalone, scallops and kelp". Changdao is China's Hawaii and has the title of "National Nature Reserve, National Scenic Area, National Forest Park, Provincial Seal Nature Reserve and Provincial Geopark". Changdao is a primitive, natural, unprocessed and unique tourist virgin land. Every island here is unique, and every scene is beautiful. The various strange reefs and rocks formed by sea erosion are simple, quiet, exquisite and clear.

In 2003, the Changdao Tourism Bureau created "Sea Fairy Mountains", "Well-off Fishermen", and "Fishermen's Sea Tours", and focused on operating this brand, integrating tourism resources, and creating a green, safe, and healthy It is a tourist destination, especially the Mazu stone, which is blessed with blessings and welcomes good fortune, has become a magnificent and wonderful flower in the folk culture of our island people.

Fairy Mountains on the Sea

In the vast sea, there is a group of gem-like green islands. This is the beautiful archipelago known as the "Fairy Mountains on the Sea" - Temple. The Island Islands, also known as Changdao, straddles the Bohai Strait between the Liaodong Peninsula and the Shandong Peninsula, facing the ancient city of Dengzhou (Penglai) across the sea. According to "Historical Records", Emperors of Qin and Han dynasties traveled tirelessly, stopped and rested their horses on the bank of Danya Mountain in Penglai, looked at the fairy mountains in the sea, and begged for immortality. This fairy mountain refers to Changdao. A Tang poem once said: "Suddenly I heard that there is a fairy mountain on the sea, and the mountain is in the void..." Su Dongpo, a great writer in the Song Dynasty, once looked at the Changshan Islands and couldn't help but admired: "It's so true." This is the home of gods!" Mythological novels such as "Journey to the West" and "Flowers in the Mirror" even describe this place as an illusory and otherworldly paradise.

Historical records record in "Historical Records 6.1 Feng Chan Shu": "Ziwei, Xuan and Yanzhao sent people into the sea to seek Penglai, Fangzhang and Yingzhou. These three sacred mountains are said to be in Bohai In the middle, the people are not far away, and if the danger comes, the wind of the boat will take them away. If there is a chance, the immortals and the medicine of immortality are there, and the animals and beasts are all white, and the gold and silver are the palace gates. They have not arrived. Like clouds; when it comes, the Three God Mountains are under the water; when they come, the wind will always pull them away, but they will never reach it."

"The Theory of Mirage" written by Lin Jingxi, a survivor of the Southern Song Dynasty, has more than 100 words in full. This is the best prose about mirage.

Lu Rong of the Ming Dynasty's "Miscellaneous Notes on Shuyuan": "The theory of mirage air towers was published in the official book of Heaven, and it came from a long way. Perhaps the mirage is a big clam, and Yue Ling's so-called pheasant entering the sea is a mirage. Yes. It may be that they are transformed into snakes. There are many such things in the sea. However, there are no towers on the seashore. It is said that they are caused by Su Changgong Haishi. The preface states that he was born in the spring and summer, but disappeared at the end of the year. He prayed in the temple of the God of the Sea. If he thought he could pray again, it was not a mirage. "

Ming Yuan Keli "Guan" "Hai Shi" and the preface: "On one day in midsummer, I went up to the middle building of the office, opened the window and looked north, and saw a majestic city in the vast and vast world. As I looked around the islands, I saw that the salt water was not the same as before, and the humble ones resisted. If you look closely at the palaces and towers, you can see the eaves, red and pink, and they all have shapes, like a canopy, a flag, a pagoda, or a puppet speaking. Thousands of spring trees are scattered far and wide, bridges are connected to each other intermittently, and they appear and disappear at different times. It is said that the fairy island of Pengcai is equipped with all kinds of supernatural things. ?" is the most realistic and appropriate article describing Haishi among the existing Penglai Pavilion poems.

Liu Xianting of the Qing Dynasty's "Guangyang Miscellaneous Notes": "Laiyang Dong Qiao said: Dengzhouhaishi, not only the shape of phantom towers and palaces, but also more than a hundred warships in one day, with fierce battles and the sound of golden drums." He fell into the water. It is also said that in the third year of Chongzhen's reign, Qiao went to Dengzhou for a small test. The local officials reported to the sea market. It is customary to report to the sea market by beating drums. , I saw a hole in the long mountain outside the north gate, like a city gate. The water came out from the inside, and the mountain was broken into two parts. On the shore, there are also people watching from the buildings, just like those seen on the shore. "Pu Songling Mountain City: Huanshan Mountain City has a high wall and stretches for six or seven miles, and it is actually a city wall" (Volume 6 of "Strange Stories from a Chinese Studio"). It is a "mountain mirage", similar to a mirage.

Mirage

Selected from "Mengxi Bi Tan"

Shen Kuo

In the sea of ??Dengzhou, there are clouds from time to time, such as palaces and terraces. , battlements, people, chariots and horses, crowns and covers are all clearly visible, so it is called the sea city. Or it may be said: "It was caused by the mirage's energy." This is doubtful. Ouyang Wenzhong once sent an envoy to Heshuo and passed through Gaotang County. There were ghosts and gods passing by in the sky at night in the post house. The sounds of carriages, horses, people and animals could be distinguished one by one. The description was very detailed, but there is no record. When I asked the elders here, they said: Twenty years ago, I passed through the county during the day and saw many people. The natives also call it Haishi, which is roughly similar to what you see in Dengzhou.

Translation

On the sea in Dengzhou, there will sometimes be clouds and mist, such as palaces and bedrooms, pavilions, battlements, people, cars and horses, and roofs of buildings. are) clearly visible, it (this scene) is called "sea city". Some people say: "(This is) formed by the dragon's breath." (I) doubt that is the case. Ouyang Wenzhong once went to Heshuo as an envoy and passed through Gaotang County. In the post house, he heard ghosts and gods passing by from the sky at night, and he could distinguish the sounds of carriages, horses, people and animals. He said it in great detail, so I won’t excerpt it in detail here. I asked a local old man and he said: "I passed through this county during the day twenty years ago, and I could clearly see people and things." The locals also called this (such a scene) "Sea City." It is roughly the same as what was seen in Dengzhou.

Mountain City

Pu Songling

Huanshan Mountain City is one of the eight scenic spots in the city, but it has not been seen for several years. Sun Gongzi Yunian and his companions were drinking upstairs. Suddenly they saw a solitary tower rising from the top of the mountain, with Qingming high up on it. Nowhere, I saw dozens of palaces, green tiles and flying rafts, and I began to realize that it was a mountain city. Not long after, the tall wall stretched out for six or seven miles and turned out to be the city wall. There are towers like buildings, halls like halls, and squares like squares. They are all vividly visible, numbering in the hundreds of millions. Suddenly a strong wind blew up, the dust and air were thick, and the city was just a blur. Now that the wind is calm and the sky is clear, everything is gone except for a dangerous tower rising directly into the sky. The building has five frames, and the windows are all open; there are five bright spots in one row, which are the sky outside the building. The layer-by-layer index means that the higher the building, the less bright it becomes. Count to eight layers and cut them like star points. And above it, it is dim and misty, and its levels cannot be calculated. On the upper floor, people were coming and going, leaning or standing. As time passes, the building becomes lower and lower, and its top is visible; gradually it becomes like an ordinary building; then it becomes like a high house; suddenly it becomes like a fist or a bean, and then it is invisible. I also heard that some early travelers saw people and shops on the mountain, which were no different from the rest of the world, so it was also called "Ghost Market".

Translation

The "Mountain City" in Huanshan Mountain is one of the eight scenic spots in Zichuan County, but it often does not appear once for several years. (One day) Mr. Sun Yunian was drinking upstairs with his friends from the same industry. Suddenly he saw a lonely pagoda standing on the top of the mountain, reaching high into the sky. (The two of them) you looked at me, I looked at you, they were surprised and confused. , thinking that there is no Buddhist temple nearby. Not long after, I saw dozens of palaces with green tiles and high ridges, and then I realized that it was a "mountain market". Not long after, a tall city wall (reappeared), (topped by) a short wall with a concave and convex shape, stretching for six or seven miles, turned out to be a city. There are buildings in the city that look like pavilions, halls, and neighborhoods. They are all clearly presented in front of you, and you can’t even count them. Suddenly a strong wind blew, blowing up huge amounts of dust, making the whole city blurry. After a while, the wind stopped, the sky became clear, and the previous scene all disappeared, leaving only a high-rise building, directly touching the sky and the Milky Way, with five rooms (on each floor), all the windows were open, and five bright places. , that is the sky outside the building.

Count up one floor at a time. The higher the room, the smaller the bright spots. When you count to the eighth floor, the bright spots are only as small as stars. The higher you go, the bright spots become dim, as if they are not there. , can’t see its level clearly. People on the (lower floor) upstairs were coming and going, each doing their own thing, some leaning on the (railing), some standing, with different postures. After a while, the building gradually became lower and the roof could be seen. Gradually, it became like an ordinary building again. Gradually, it turned into a tall bungalow. Suddenly it shrank to the size of a fist. ( Then it shrunk to the size of a bean, and finally disappeared completely. I also heard that people who got up early and rushed on their way saw homes, markets and shops on the mountains, which were no different from the situation in the world, so people called it " Ghost market”.