Twenty-four solar terms were originally formulated according to the bucket handle rotation direction of the Big Dipper, which rotates circularly and is closely related to the seasonal changes. The Big Dipper is an important astrology in the northern hemisphere. It will appear in different directions in the northern hemisphere sky in different seasons and at different times at night. It is a ruler for the ancients to set directions and solar terms. The law that the Big Dipper revolves around Polaris from east to west was called "star shift" by the ancients. Through this law, people can judge the time of solar terms. The so-called: "bucket handle refers to the east, and the world is spring; Bucket handle guide, the world is summer; Bucket handle refers to the west, and the world is autumn; Bucket handle refers to the north, and it is winter in the world. " Because the 24 solar terms are determined by the rotation direction of Beidou bucket handle, this calendar is also called "ephemeris". During the period of Emperor Wu of the Western Han Dynasty, "Twenty-four solar terms" were incorporated into the calendar as a supplement to the calendar guiding agriculture. In the Yellow River basin, the day with the longest sun shadow and the shortest day is the winter solstice, and the winter solstice is the starting point of the "24 solar terms". The winter solstice and the next winter solstice are divided into 24 equal parts, and the time between each solar term is equal. The current "twenty-four solar terms" come from the "fixed gas method" concluded more than 300 years ago (it has been used since 1645). From the establishment of the constitutional calendar to the present, the "Lunar Calendar" and the "Twenty-four Solar Terms" are determined according to the position of the sun on the regression ecliptic, that is, on a "ecliptic" with a circumference of 360 degrees (the apparent path of the sun on the celestial sphere for one year), it is divided into 24 equal parts, one for each 15, and the starting point is 0 degrees in spring (sort

Tea picking in Grain Rain: There is a custom of picking tea in Grain Rain in the south, and Grain Rain tea is also tea before rain, which is spring tea picked in Grain Rain season, also called spring catechu. The moderate temperature and abundant rainfall in spring, coupled with the recuperation of tea trees in winter for half a year, make the buds and leaves of spring shoots plump, green in color, soft in leaves, rich in vitamins and amino acids, and make the taste of spring tea fresh. It is said that Grain Rain tea on this day can clear fire, ward off evil spirits and improve eyesight. So no matter what the weather is in Grain Rain, people will go to Chashan to pick some new tea and come back to soak in water.

Sacrifice to the sea: Grain Rain Festival is also called the "strong festival" for fishermen to go fishing in the sea. [12] In Grain Rain season, the sea is getting warmer, and hundreds of fish go to the shallow sea, which is a good day to go fishing. As the saying goes, "Go online by Grain Rain." In order to go to sea safely and return home with a full load, fishermen will hold a sea sacrifice in the Grain Rain on this day and pray for Poseidon's blessing. Therefore, the Grain Rain Festival is also called the "strong festival" for fishermen to go fishing. In the past, every village had a temple of the sea or mother. When it's time for sacrifice, fishermen carry their offerings to the front of the temple for sacrifice, while others carry them to the seaside, beating gongs and drums, setting off firecrackers and offering sacrifices to the sea. The scene is very grand.

Go to Grain Rain: There was a custom of "going to Grain Rain" in ancient times. On this day in Grain Rain, young women went to visit relatives in the village, and some people came back after walking in the wild. The implication is to integrate with nature and keep fit.

Eating Spring: Before and after Grain Rain, Toona sinensis was mellow and refreshing, with high nutritional value, so it was said that Toona sinensis was tender as silk before rain. People say that picking and eating Toona sinensis in spring is "eating spring". Toona sinensis is generally divided into purple Toona sinensis buds and green Toona sinensis buds, especially purple Toona sinensis buds.

Sacrifice to Cang Xie, Wen Zu: According to legend, since the Han Dynasty, there has been a custom of offering sacrifices to Cang Xie, Wen Zu in Baishui County, Shaanxi Province. According to legend, Cang Xie created characters and made great contributions to the world. The Yellow Emperor was moved by it and took "Grain Rain" as his reward for creating characters. Since then, there has been a "Grain Rain Festival". Since then, every year during the Grain Rain Festival, nearby villagers will organize temple fairs to commemorate Cang Xie. [ 13]

Grain Rain posted a ban on killing five poisons. After Grain Rain, the temperature rose, and pests and diseases entered a high breeding period. In order to reduce the harm of plant diseases and insect pests to crops and people, farmers erected Grain Rain columns to pray for exorcism and good luck. This custom is very popular in Shandong, Shanxi and Shaanxi. In the old days, a Japanese Grain Rain painting, Zhang Tianshi, was posted on the door in Linfen, Shanxi, named "Forbidden Scorpion". Shaanxi Fengxiang Scorpion Curse is woodcut, which shows that there is a great demand. It was printed with the words: "In Grain Rain, in mid-March, scorpions showed off their bravado. God chicken bites, poisonous insects turn into water ... "In the center of the picture, the rooster holds the insect with a big scorpion under his paw. This painting is printed with a spell. The saying that the rooster cures the scorpion has been circulating among the people for a long time. Scorpions are also forbidden in Shandong folk customs. Xiajin county annals in the sixth year of Qing Qianlong: "Grain Rain, cinnabar forbids scorpions." The folk custom of "banning scorpions" reflects people's feelings of expelling pests and longing for harvest and peace.

Flower viewing, around Grain Rain, is also an important time for peony to blossom. So peony flower is also called "Grain Rain flower". "Three generations of Grain Rain visited peony", and peony appreciation became an important recreational activity in people's leisure time.