What is the solar halo in the Book of Changes?

The ancients thought that the solar halo was an ominous sign, indicating disaster. Solar halo is a common atmospheric optical phenomenon, and its formation is related to high clouds.

High clouds are generally composed of tiny ice crystals, which are equivalent to a prism. When sunlight passes through the ice crystals contained in high clouds, it will be refracted and reflected twice, forming a solar halo. Because the high clouds containing ice crystals are generally the "Depth Charge" invaded by thunderstorms, the appearance of solar halos often indicates that the weather will turn bad in a short time. Therefore, there is a saying in folk proverbs that the sun is dizzy in the middle of the night and the moon is dizzy at noon.

Solar halo, also called round rainbow, is an atmospheric optical phenomenon, which is formed by the refraction or reflection of ice crystals when sunlight passes through cirrostratus. When light enters the ice crystals in cirrostratus, it is refracted twice and dispersed into light of various colors in different directions. The viewing angles of the solar halo radius are usually 22 degrees and 46 degrees. People can usually observe the phenomenon of "solar halo" with the naked eye. The greater the ice crystal content in the clouds, the more obvious the halo, which is easy for people to observe. On the other hand, a "solar halo" cannot be formed, or even if it is formed, it cannot be clearly observed on the ground. Solar halos mostly appear in spring and summer. There is a folk proverb that "it rains in the middle of the night when the sun is dizzy, and it is windy at noon when the moon is dizzy", which means that if there is a solar halo, it will rain in the middle of the night, and if there is a lunar halo, it will be windy at noon the next day. To some extent, solar halo can be a precursor of weather change, and it may turn cloudy or rainy, but there is no scientific basis to say that this phenomenon can predict climate drought, floods and earthquakes. Don't watch with the naked eye for a long time when the solar halo appears, so as not to burn your eyes. When it's going to rain, cirrus clouds like bird feathers often appear in the sky, and then a rainy cirrostratus appears in the air about 6 kilometers below the cirrus clouds. Due to the low temperature, the water droplets in the cloud become small ice crystals in the shape of hexagonal prisms. When the sun's light energy passes through the clouds, it will be refracted to small ice crystals. It seems that there is a circle around the sun, and the spectrum is from the inside out. This is a solar halo.