Why are there many thunderstorms and heavy rains in summer?

High temperature and humidity are the main conditions for the formation of thunderstorms.

In summer, the temperature is higher, the water evaporates more, the air humidity is higher, the clouds are thicker, and friction discharge is more likely to occur between clouds, so there are more thunderstorms in summer.

In winter, controlled by the continental cold air mass, the air is cold and dry, the solar radiation is weak, and the air is not easy to form violent convection, so thunderstorms rarely occur. But sometimes the weather is warmer in winter, and the force of warm and humid air flow is stronger. When the cold air in the north occasionally moves south, the warm and humid air is forced to rise, and the convection intensifies, which will form thunderstorms. The occurrence of thunderstorms does not depend on the temperature itself, but on the upper and lower distribution of temperature. That is to say, although the temperature is not high in winter, if the temperature difference between the upper and lower reaches a certain value, strong convection can also be formed, resulting in thunderstorms. Thundering in winter is rare in China, but it often happens in Toronto in winter.