According to media reports, on July 19, a solar halo and horizon arc appeared in the sky of Beijing. The scenery is spectacular and beautiful. At noon on Monday, a solar halo appeared over Beijing. Even more surprising is that there is a colorful rainbow around the aperture. Citizens and tourists gathered to take pictures.

Corona, also known as round rainbow, is an atmospheric optical phenomenon. When sunlight passes through cirrostratus, it will be refracted or reflected by ice crystals. When light hits the ice crystals in cirrus clouds, it will be refracted twice and split into different colors in different directions.

Circumferential horizontal arc is also called daily load or daily load phenomenon. There are also folk proverbs about colorful clouds and flaming rainbows. The horizontal line is called the most beautiful halo image, and the color sequence is red, orange, yellow, green, blue, indigo and purple from top to bottom.

Extended data:

The principle of solar halo and circumterrestrial arc;

When the solar halo appears, don't observe it with the naked eye for a long time to avoid burning your eyes. When it rains, cirrus clouds like bird feathers often appear in the sky, and then cirrus clouds with rain will appear about 6 kilometers below them. Due to the low temperature, the water droplets in the cloud turned into hexagonal ice crystals. When sunlight passes through the clouds, it refracts on small ice crystals, forming a circle with spectral colors around the sun from the inside out. This is called halo.

When the sun is at least 58 degrees above the horizon, an arc will appear around the horizon, but in mid-latitude areas, the sun will only reach this height in June and early July, and it will only appear in a few hours around noon. Its formation principle is similar to environmental arc, which is formed by the refraction of solar light by ice crystals in the upper atmosphere. The difference is that the incident light of the circular arc enters from above the ice crystal, so the color sequence of the reflection is opposite to that of the circular arc.

References:

Beijing Daily-Beauty! Sunlight and colorful clouds appear in the sky of Beijing at the same time.