The appearance of halo indicates that the weather system will ...?

Halo is an optical phenomenon formed by the refraction and reflection of sunlight or moonlight by ice crystals suspended in the atmosphere.

Ring, arc, cylinder or bright spot.

Halo only occurs when cirrostratus exists, and cirrostratus is often hundreds of kilometers away from the rain front area. With the advance of the front, the rain area may move in the near future, so the halo often becomes a precursor of rainy weather.

Halo occurs in cirrus clouds and cirrostratus, and is often associated with frontal cloud systems. Before the cold and warm front, the warm and humid airflow rises along the front, forming a cirrostratus at high altitude. As the front progresses, there will be precipitation and strong wind before and after the front passes through the mirror. So there is a proverb that "the sun is dizzy in the middle of the night and it rains, and the moon is dizzy at noon".

The practice of contemporary meteorological science shows that when the weather turns from sunny to cloudy to rainy, people first see cirrostratus, and then there will be low clouds in the sky, which will produce rainfall. When cirrostratus will appear depends on whether low clouds develop. If they do this, the result will be rain. This is the main sign to judge whether there is wind and rain after the sun and moon are dizzy. Whether it is dizziness for several days in a row or a flash in the pan, it depends on the development speed of low and medium clouds after dizziness. The development of middle and low clouds moves in quickly, and precipitation comes quickly; Development moves in slowly, and precipitation comes late; If you don't move in, there will be no precipitation.