Strange phenomena and scientific principles in the desert

Looking at the sea, or sailing on the sea, sometimes in a calm and windless situation, you will suddenly see strange phenomena such as ships, islands, towers and city walls reflected in the air. When the wind is strong, this scene will disappear immediately. This is an illusion in the atmosphere, called a mirage. This phenomenon occurs not only on the sea surface, but also in the air layer of lakes, rivers, deserts and Gobi. In Song Dynasty, Shen Kuo recorded this illusion in Meng Qian's Bi Tan: "There are clouds in the sea of Dengzhou, such as temples, city maps, chariots and horses, which are vivid in my mind." Dengzhou, now Penglai County, Shandong Province, is located on the south bank of the Bohai Sea, with Miaodao Islands in the Bohai Sea, dozens of kilometers away from Penglai. What is recorded here is the illusion of miaodao islands seen by Penglai.

In ancient times, because it was impossible to explain the causes of this phenomenon scientifically, it was endowed with various myths and legends, and a natural mirage was regarded as a mirage. In fact, the mirage is formed by the strong abnormal refraction of light in the atmosphere under special meteorological conditions. The refraction of light refers to the phenomenon that the speed of light changes and the direction of progress twists and turns under different air densities. When you insert a straight rod obliquely into the water, it looks like it is broken from the side! This is caused by light refraction. In summer, the temperature of seawater is low during the day, and the lower air is colder than the upper air due to the influence of water temperature, resulting in the inversion phenomenon that the upper air is cold and the lower air is warm, so the lower air density is particularly high, while the upper air density is particularly low. When the light of the distant scene gradually refracts from the dense air layer to the sparse air layer, it is totally reflected in the upper layer and then returns to the dense air in the lower layer. After this winding route, a mirage will appear in the eyes of the observer. Because people's vision always feels that the image comes from a straight line, the image we see is much higher than the real thing. This phenomenon is also called a mirage.

In the desert, because the sand is scorched by the sun during the day, the air near the sand layer rises very fast, forming a temperature distribution in which the lower layer is hot and the upper layer is cold, resulting in the phenomenon that the air density in the lower layer is much lower than that in the upper layer. At this time, the light of the front scene will be refracted from the dense air to the less dense air, thus forming a mirage. From a distance, it looks like a reflection in the water. People who travel long distances in the desert are hot and thirsty. When they see a mirage, they often mistakenly think that they have reached the cool lake. However, a gust of wind and sand swept through, and it is still an endless desert. This scene turned out to be just an illusion.

There is a kind of "gravel circle" in the desert, which is wonderful. It is a big stone that expands with heat and contracts with cold for hundreds of years, and it is rolled again and again, forming a round gravel circle on the ground, much like a manual arrangement, but it is actually formed naturally.

Desert news

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Australian rocks that tell the time

Can the stone tell the time? It sounds almost impossible, but in the vast desert southwest of Alice in central Australia, there is indeed a strange stone that can tell the time. This strange stone standing in the desert is 348 meters high and about 8000 meters in circumference, and its exposed part alone may weigh hundreds of millions of tons.

This strange stone tells people the passage of time by changing its color regularly every day: in the morning, when the sun shines, it is brown; At noon, when it is in the sky, it is gray-blue; In the evening, when the sun goes down, it is red. It is the "standard clock" of local residents, who arrange agriculture and daily life according to its color change three times a day.

The strange stone will not only change color with the intensity of sunlight, but also change its image with the change of the angle of sunlight: sometimes it looks like the dorsal fin of a huge shark roaming leisurely in the sea; Sometimes it is like a black submarine floating on the sea; Sometimes like a giant in Tsing Yi, he lies on a soft white bed. ...

Why does the strange stone have the function of "seeing time"?

In order to explain the "collision" phenomenon of strange rocks, many archaeologists and geologists have made a detailed investigation on the climatic conditions and geographical environment in which strange rocks are located, and made a deep study on the structural components of strange rocks. Some scientists try to explain the "strange phenomenon" caused by the strange stone: the strange stone changes color because it is in a flat desert, and the sky is finally cloudless in Wan Li, the air is thin and the surface of the strange stone is smooth. In this case, the surface of the strange stone acts as a mirror, which can strongly reflect sunlight, so the color change in the sky from morning to evening can be presented on the strange stone accordingly.

The image of grotesque rocks changes because of the number and angle of reflection and refraction caused by the sun's activities in different climatic conditions, and this change is reflected in the human eye and becomes a grotesque shape.

Scientists' statement about the strange stone "telling the time" can't fully explain the cause of the strange stone phenomenon, but it also solves a little mystery for the world.

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There is a kind of "gravel circle" in the desert, which is wonderful. It is a big stone. After hundreds of years of brilliant cold shrinkage and repeated fragmentation, it forms a round gravel circle on the ground, which looks like a man-made work, but it is actually naturally formed.