Analysis of the Microphysical Precipitation Mechanism for a Cold Vortex Process

The distribution characteristics of microphysical elements, growing mechanism of precipitation particle and evaporation effects of subcloud raindrop in a cold vortex process are analysed. The results show that the cloud system consists of two vertical lavers, lower warm stratocumulus and principal cool altostratus. The altostratus base is 2 km high, and cloud top is higher than 5 km. The supercooled water exists abundantly in the cloud, the maximum is up to 0.21 g · m – 3 at – 11.20℃, but its distribution is not homogeneous, 87% of continuous distribution width are less than 2.4 km, which is disadvantage to the rime increasing of ice crystal in the cloud. Meanwhile, the evaporation effect of subcloud raindrop is very big, the diameter of raindrops which could not arrive the ground is less than 1 mm. Therefore, the cold vortex process produces the weak precipitation.