Causes of severe convective weather

Strong convection is actually a weather phenomenon caused by strong vertical movement of air. The most typical is the strong convective weather in summer afternoon: during the day, the ground constantly absorbs short-wave radiation from the sun, and the temperature rises, releasing long-wave radiation to heat the atmosphere. When the air near the ground receives enough heat from the earth's surface, it will expand and reduce its density, and then the atmosphere will be in an unstable state. It's like oil and water in a water tank. When the less dense oil is at the bottom of the water tank and the water is at the top, there will be a strong upward movement, and finally the oil will float to the water surface. In the same way, the hot air near the ground rises under the buoyancy, forming a rising hot and humid airflow. When it rises to a certain height, the water vapor contained in the air will condense into water droplets due to the temperature drop. When water droplets fall, they are picked up by stronger updraft, and so on. Small water droplets begin to accumulate and integrate into large water droplets until the upper air cannot support their weight, and finally they fall into the rain. This is why thunderstorms in summer are not as rainy as spring rains in Mao Mao, and the water drops are bigger.

Of course, the physical process of the formation of various severe convective weather is not exactly the same, which is closely related to the influence of dynamic and thermal effects of the underlying surface. Moreover, strong convective weather is based on large-scale weather systems, which affects or determines the generation, development and movement of small and medium-scale weather systems. For example, during the Meiyu period, a wide range of cold and warm air meet to form a Meiyu front rain belt, which will produce heavy rain in some areas if it is matched with favorable conditions such as topography.