Look at the clouds and you will know what the halo and China in the weather mean respectively.

When thin cirrus clouds or cirrostratus composed of ice crystals appear in the sky, there will be some colorful rings and circles around the sun and the moon, which are called solar halos.

China is also a weather phenomenon. When there are thin clouds in the sky, you can see the colorful halo around the sun or moon through the clouds. Its color sequence is ultraviolet red, which can be repeated up to 3 times. The halo closest to the luminophore in China is called. The inside of the flower is white or bluish white, the middle is yellow, and the outer edge is reddish brown. Its angular radius is usually less than 5, and generally only includes the crown. However, the angular radius of a well-developed crown can reach 10. Porcelain is produced by the diffraction of sunlight or moonlight between water droplets or ice crystals in clouds. The smaller the droplet diameter, the larger the halo. The more uniform the droplet size, the brighter the halo color. Therefore, by measuring the opening angle of China color ring, the average size of cloud droplets can be roughly estimated. After the volcanic eruption, a large amount of volcanic ash is suspended in the air, which is similar to the wavelength of light waves. When they float under the sun or the moon, they can also produce China-like colored halos due to diffraction, and the angular radius is about 22, which is called Bi Xufu Halo. China is a local weather omen. If it changes from halo to China, and the opening angle of China is decreasing, it means that there are more water droplets in the clouds, and the clouds become thicker, which may lead to precipitation.

Baidu encyclopedia is more detailed, I suggest you have a look.