What's Tomb-Sweeping Day angry about?

Qingming is one of the 24 solar terms in China. Every year on April 5th or 6th of Gregorian calendar, when the sun reaches longitude 15, it is Tomb-Sweeping Day Qi. "Twenty-four solar terms" said: "March Festival, ... at this time everything is clean and clear." Therefore, "Qingming" means the melting of snow and ice, lush vegetation, sunny weather and prosperity of everything. Famous sentences such as "the willow shoots are green and smoky, and the February sky is clear", "the solar terms are clear and the peaches and plums are smiling" and "the original vegetation in the suburbs is soft after the rain" are vivid descriptions of the phenology of heaven and earth in the Qingming season.

Qingming is a solar term representing phenology, which means sunny weather and lush vegetation. Tomb-Sweeping Day has folk customs such as climbing mountains, eating cold food and sweeping graves. However, before and after Tomb-Sweeping Day, cold air still invaded from time to time, even making the average daily temperature lower than 12℃ for more than three consecutive days, resulting in rotten seedlings of middle rice and dead seedlings of early rice. Therefore, it is necessary to avoid warm tail and cold head when sowing and transplanting rice. In the northwest plateau, livestock are weak under the influence of severe winter and insufficient forage, so it is necessary to guard against the harm of strong cooling weather after spring to old, weak and young livestock.

"There are many rains during the Qingming Festival" is a portrayal of the spring rain in the south of the Yangtze River by Du Mu, a famous poet in the Tang Dynasty. But in some areas, this is not the case. Especially in the western part of South China, it is often in the spring drought period, and the rainfall in early April is generally only 10 to 20 mm, which is less than half of that in the south of the Yangtze River. Although there are many spring rains in eastern South China, the rainfall in early April is generally only 20 to 40 mm, so natural precipitation is not enough for agricultural production, so it must be replenished by storing water years ago. In addition, May-June is the month with the most hail in a year, so the prevention of hail disaster should be strengthened.