What is a shear line?

Shear line refers to the discontinuous line of wind direction or wind speed, which is actually the dividing line between two opposite airflow.

In other words, the shear line is a long and narrow area where the wind direction or wind speed changes sharply. The shear line is different from the front, and the temperature difference between the two sides of the shear line is not obvious, but the horizontal cyclone shear of the front is very large.

The shear line can appear on the ground and at high altitude, but it mainly appears at 700 HPA or 850 HPA. There is a strong convergence near the shear line, and precipitation weather often occurs. Generally speaking, precipitation occurs in the area south of the 700 HPA shear line and north of the 850 HPA shear line.

Extended data:

Characteristics of shear line:

According to the type of wind field, it can be divided into cold front, warm front, quasi-static front and north-south shear.

The distribution of precipitation on the shear line is very uneven, and heavy rains often appear in areas with strong convergence and sufficient water vapor supply. The eastward movement of southwest vortex along shear line is often the main reason for enhancing convergence. High-altitude shear lines can appear all year round, but mostly in late spring and early summer when cold and warm air moves frequently.

The weather where the shear line is formed changes with the seasons. In winter, due to the low water vapor content in the air, the atmospheric stratification is relatively stable, with more continuous precipitation and a wider precipitation area, but less precipitation.

Reference source: Baidu Encyclopedia-High altitude shear line

Reference source: Baidu Encyclopedia-Clipping