宁夏中北部地区沙尘暴天气发生过程中的不稳定条件分析

从沙尘暴的形成条件入手，对宁夏中北部地区近30a来沙尘暴天气发生过程中的不稳定条件进行了较为详尽的分析。结果表明：沙尘暴发生三前，大气的不稳定性明显增强；沙尘暴天气发生时不稳定性主要发生在700hPa以下，最为突出的是850hPa以下；沙尘暴发生过程中不稳定性达到最强。

Analysis on Unstable Condition in Sandstorm Processes in Middle and North Area of Ningxia

The atmospheric stability in the processes of sandstorm taking place in the middle and north area of Ningxia was classified by using the P-T method and based on the general weather data for 30 years. Meantime the Richardson parameters of each altitude were computed. The atmospheric instability became more obvious just before sandstorm, and it mainly took place at altitude below 700 hPa, especially below 850 hPa. The atmospheric instability has already occurred at least one day before sandstorm taking place, and the long time accumulative process the long persisting time of strong sandstorm. The abruptly happened sandstorm rapidly accumulated its unstable energy before its happening. When the energy became the strongest, sandstorm took place. The atmospheric instability will gradually disappear after sandstorm ending.