Climate change around Tomb-Sweeping Day.

Before and after Tomb-Sweeping Day, the warm and humid air flow became active, the atmospheric circulation began to change to summer type, and the temperature in various places continued to rise. In addition, the warm and humid airflow is active, and the cold air still has a strong southward force, which makes the cold and warm air frequent and makes the precipitation increase a lot compared with winter. Because the temperature is suitable and the precipitation increases, this period of time is also the time for all localities to start spring sowing. However, because the cold air still has a certain intensity at this time, it can form a cold wave southward, which greatly reduces the temperature and forms a spring freezing injury. Therefore, when sowing in spring, we should pay attention to the freezing injury and late frost threat caused by strong cold air going south to crops.