What is the origin of the slight cold solar terms?

On June 5th or 6th every year, at 5438+ 10, the sun reaches 285 hours, which is referred to as slight cold.

Cold), like severe cold, slight summer heat, great summer heat and summer heat, is a solar term indicating temperature change. "Twenty-four solar terms": "December solar terms, the first cold is still small, so the cloud. It will be big in half a month. " A slight cold means that the weather is already very cold. The periods of slight cold and severe cold in most parts of China are generally the coldest. As soon as the "slight cold" passes, it will take three or nine days to "get out of the ice".

In ancient China, slight cold was divided into three stages: "The first stage is to wait for Yanbei Township, the second stage is to wait for magpies to nest, and the third stage is to wait for pheasants to swim". The ancients believed that the geese among migratory birds migrated along the yin and yang, and at this time, the yang had moved, so the geese began to move northward; At this time, magpies can be seen everywhere in the north, feeling the yang and starting to build nests; The third time, the word "pheasant" means singing. When the pheasant approaches April 9, it will feel the growth of Yang and sing.