Who knows what the meteorological shear line means? what do you think?

The dividing line between two horizontal air flows in different directions of cyclone (counterclockwise in the northern hemisphere) is called shear line. On the weather map, it is shown as a discontinuous wind direction line. In meteorology, the shear line generally refers to the weather system on the isobaric surface at low altitude of 850 HPA or 700 HPA. On the shear line, the airflow often has horizontal convergence and upward movement, which is easy to produce rainy weather. Shear lines may appear all year round, but they are most frequent in late spring and early summer. Spring activity is in South China, which is called South China Shear Line. At the turn of spring and summer, it is mostly located in the Jianghuai basin, which is called the Jianghuai shear line. From mid-July to August, it mainly appears in North China, which is called North China Shear Line. The distribution of precipitation on the shear line is very uneven, and heavy rains often appear in areas with strong support and abundant water vapor supply.