2021年5月甘肃白银一次强对流天气过程诊断分析
Diagnostic Analysis of a Strong Convective Weather Process in Baiyin, Gansu Province in May 2021

本文对2021年5月22日在甘肃省白银市一次强对流天气的进行分析，从强对流天气过程的形成和发展过程，实况、环流形势、水汽条件、动力条件以及不稳定能量方面进行分析，在700 hPa上有较为显著的冷平流，冷暖气团在甘肃省南部地区的交汇处较为显著，为不稳定天气的产生与发展提供了较好的热力条件；在此次强对流天气过程中产生的降水，是由中低层水汽的不断聚集，并与高空干冷空气交汇所造成的；在白银地区上空有着强烈的垂直运动，动量交换频繁，加之空中槽过境，为强对流天气的发生发展提供了较好的动力条件；西北向东南倒灌的湿冷空气加强了南北温差，冷暖空气的交汇进一步加剧，使得大气层结不稳定度也增大。同时随K指数的增加，温度差也增大，这表明在垂直方向上的湍流运动增强，为强对流天气的形成与发展提供了较为有利的热力不稳定条件。
This paper analyzes a severe convective weather in Baiyin City, Gansu Province on May 22, 2021, from the aspects of the formation and development process of the severe convective weather process, the actual situation, circulation situation, water vapor conditions, dynamic conditions and unstable energy. There is a relatively significant cold advection at 700 HPA, and the intersection of cold and warm air masses in the southern region of Gansu Province is relatively significant, It provides better thermodynamic conditions for the generation and development of unstable weather; the precipitation produced in this severe convective weather is caused by the continuous accumulation of water vapor in the middle and lower layers and the intersection with the upper dry and cold air; strong vertical motion, frequent momentum exchange and air trough transit over Baiyin area provide good dynamic conditions for the occurrence and development of severe convective weather; the wet and cold air pouring from northwest to Southeast strengthens the north-south temperature difference, and the intersection of cold and warm air is further intensified, which also increases the instability of atmospheric stratification. At the same time, with the increase of K index, the temperature difference also increases, which indicates that the turbulent movement in the vertical direction is enhanced, providing a more favorable thermal instability condition for the formation and development of severe convective weather.