How did the lunar halo come from?

When the moon's light passes through the high and thin cirrostratus, it is refracted by ice crystals, so that the seven-color composite light is dispersed into an annular or arc-shaped internal infrared violet, and an aperture is generated around the moon. In ancient times, the lunar halo was called the hairy moon, and in some places it was also called the wind circle. Both solar and lunar halos are refracted by ice crystals, just like the principle of rainbow. There is a folk proverb: "The sun is dizzy in the middle of the night, it rains in the middle of the night, and the moon is dizzy at noon."

The appearance of solar halo or lunar halo often indicates that the weather will change to a certain extent. Generally, a solar halo means it may rain, and a lunar halo means it will be windy. Sometimes there is a gap in the lunar halo, and the direction of the gap is the direction of the wind. Cirrostratus itself will not produce rain, but it may rain in the middle and low clouds, and there is a lot of water.

If they continue to develop, the clouds will increase and thicken, and it will be windy and rainy. Whether it is "halo" for several days in a row or "halo" for a short time, it depends on the development speed of low and medium clouds after "halo". The development of middle and low clouds moves in quickly, and precipitation comes quickly; If the development is slow, the precipitation will come late; If you don't move in, there will be no precipitation.

In photography, halo refers to the optical effect caused inadvertently, which is due to the reflected light in the initial exposure of the negative, or the aperture formed by the image printed on this negative around the edge of the light source or the anti-light source. Modern photographic negatives will be covered with "anti-halo layer" to prevent this effect.