Why is spring the rainy season?

Meiyu season is in summer, especially in the middle and lower reaches of the Yangtze River in China. After beginning of spring, due to the rising temperature in the northern hemisphere, warm and humid air currents in the Pacific Ocean and Indian Ocean began to affect China. But cold air activity is still very common. Under the influence of cold and warm air, China will enter the spring rainy season in beginning of spring, Rain, Scare, Qingming and Grain Rain. The rainy season at this time is not called rainy season, and the specific name is not very clear. Generally, only when it rains does China enter the rainy season.