Explain weather phenomena

High altitude trough: the trough line in the center of high altitude and low pressure.

When a low-pressure center appears at high altitude and moves over Chongqing, low altitude is a high-pressure center. This air movement moves from Chongqing to its vertical sky, so it is a convection movement.

Bottom shear convergence system: right thumb up, four fingers in the palm. The movement of your four fingers is just like the air movement around Chongqing.

When the air at the bottom of Chongqing rises, it becomes a low-pressure center relative to the surrounding area, and the surrounding air will move to Chongqing as a low-pressure center, making a convergence movement, thus forming a convergence system.

South wind airflow: generally refers to the airflow from the south (southeast airflow or southwest airflow). Needless to say, the airflow in the south is hot and humid.

So once these humid air rises, the temperature will drop, and the water vapor in the air will condense into water droplets, forming heavy rainfall. It's convective rain

Convective weather: In fact, after the low pressure center is formed due to the sharp rise of air, the rainy weather formed in the atmospheric convection movement is convective weather. This is the reason for the afternoon rainstorm in Chuanchuan.

This knowledge is in the geography book.