Why is there a halo around the sun on May 19, 2010 in Xiping County, Zhumadian City, Henan Province

It’s the solar halo. The solar halo is a light phenomenon formed by refraction of sunlight when it passes through ice crystals in clouds. It forms a ring around the sun and appears colorful. The appearance of a solar halo often indicates certain changes in the weather. Solar halo is a relatively rare celestial phenomenon. "Solar halo" has full halo and gap halo. The solar halo is a colored or white halo or light arc formed by cirrus clouds and cirrostratus clouds surrounding the sun. The color bands are arranged in infrared and purple. Solar halos, sometimes called "flails," come in full halos and notched halos. According to experts, the solar halo is an atmospheric optical phenomenon that is formed when sunlight passes through cirrostratus clouds and is refracted or reflected by ice crystals. When light strikes ice crystals in cirrostratus clouds, it is refracted twice and dispersed into various colors of light in different directions. In fact, when there are cirrostratus clouds, there are countless ice crystals floating in the sky. The ice crystals on the same circle around the sun can refract light of the same color into our eyes to form an inner infrared and purple halo. When there are cirrostratus clouds composed of ice crystals in the sky, one or more infrared-purple colored rings with the sun as the center often appear around the sun. Sometimes many colored or white light points and arcs will appear. These rings, Points of light and arcs of light are collectively called halos. When the corresponding viewing angle of the halo radius is between 22 and 46 degrees, people can observe the "halo" phenomenon with the naked eye. The greater the ice crystal content in the clouds, the smaller the "halo" shape that appears after refraction of sunlight, and the more prominent the halo is, making it easier for people to observe; on the contrary, a "halo" cannot be formed, or even if it is formed, it cannot This phenomenon is clearly observed on the ground. "Solar halos" mostly appear in spring and summer. There is a proverb among the people that "it rains when the sun is around three o'clock, and there is wind when the moon is around noon." This means that if there is a sun's halo, it will rain at midnight, and if there is a moon's halo, it will be windy at noon the next day. Solar halo can be a precursor to weather changes to a certain extent. When a corona occurs, the weather may turn cloudy or rainy. But there is no scientific basis for saying that this phenomenon can predict droughts and floods in this year's climate. When a solar halo appears, do not look at it with the naked eye for a long time to avoid burning your eyes.