中文摘要：

2005年4月6日、19日辽宁省出现了两次降水天气过程。通过资料显示，这两场降水的影响系统，虽然都主要是北涡南槽的天气系统（这里的北涡南槽是指，由蒙古至贝加尔湖低涡和河套地区东部的高空槽以及槽前的西南气流组合的耦合系统）。但是由于具体影响的物理因子的不同，所以产生的降水性质也不同。6日的降水是不稳定的雷阵雨天气，是由中小尺度不稳定雷雨云团与东北西部东移的低压冷锋相结合的物理过程；19日是以稳定性降水为主，伴有阵雨、雷阵雨的混合性降水天气，是由东移的蒙古低涡与河套地区东部高空槽相结合的物理过程。

英文摘要：

There are two different precipitation nature weather courses in Liaoning on April 6--19, 2005. Analysis showed that both main synoptic systems are northern vortices and southern trough, though the physical variables are different. On April 6 the precipitation nature is an unstable thunderstorm or shower and physical course is the combination of meso-small scale unstable thunderstorm and low-pressure system-cold-front in the west of northeast. On April 19 the precipitation nature is stable, accompanied with shower and thunderstorm, and the physical course is the combination of Menggu low system and upper trough in the south of Hetao area.