A rare line of sky appears in the sky of Xiamen. How did this phenomenon form?

? What appears in Xiamen is a solar halo, a sun surrounded by a rainbow.

After rain, we usually see a semi-arc or circular rainbow. When an annular rainbow appears, there are often cirrostratus clouds floating in the sky. When the sun's rays pass through cirrostratus clouds, there is a circle of ice crystals around the clouds. The light rays pass through the clouds and ice crystals and are refracted twice. In this way, the sunlight will be Light beams of various colors are dispersed, forming a rare ring-shaped rainbow. This phenomenon is also called "solar halo". The solar halo is divided into two types: full halo and notch halo. Its appearance often indicates that the weather will change. The color of annular rainbow halo is usually inner infrared and purple, and its appearance usually indicates that it will rain. To put it in layman's terms, the ice crystals in the clouds act as lenses, the sun acts as a point light source, and the sky acts as a lamp with hundreds of kilometers of holes, scattering light.

When there are cirrostratus clouds, countless ice crystals will float in the sky, forming an inner infrared and purple halo when the sun hits people's eyes (actually there is no such thing). There are cirrostratus clouds composed of ice crystals in the sky. Sometimes, one or more colorful rings with the sun as the center and inner infrared and purple appear around the sun. Sometimes many colored or white light points and light arcs appear. These rings, light points and light arcs are collectively called ice halos.

"Solar halo" mostly appears in spring and summer. There is a folk proverb "Sun halo rains at midnight, moon halo winds at noon", which means that if there is a solar halo, there will be rain at midnight. If a moon halo appears, it will be windy at noon the next day. There is also a colorful halo smaller than the halo, called "hua". The color arrangement is ultraviolet red, which is exactly the opposite of the halo. The edge part. The Huahuan changes from small to large, and the weather tends to be sunny. The Huahuan changes from large to small, and the weather may turn to cloudy and rainy. In summer, when the sky clears after the rain, a colorful arc will often hang on the cloud curtain opposite the sun. This is a rainbow. The solar halo can be a precursor to weather changes to a certain extent. The appearance of a solar halo indicates that the weather may turn cloudy or rainy, but there is no scientific basis for saying that this phenomenon can predict climate droughts and floods.