To the large - scale atmosphere , we separate the terms of the horizontal vorticity converting into the vertical vorticity , which considered as the baroclinic terms , from the terms that not including horizontal vorticity by the rules of the p coordinate transforming to the z coordinate in the traditional vorticity equation , and carry out the scale analysis , and then conclude that the baroclinic terms are able to reach the same magnitude grade as the partial derivative of the vertical vorticity to time when it takes place the large scale precipitation in the summer monsoon period in china . by analyzing the game reanalysis data from april to august in 1998 in the region of chinese continent , we found that the baroclinic terms is important to the large - scale cyclone developing above the 600hpa , and the magnitude changing of the baroclinic terms is nearly in - phase as the monsoon movement , so which imply exactly that the magnitude changing of the baroclinic terms is the one of the natural characters of the summer monsoon evolution and equivalent to the movement rule of the subtropical high of the western pacific 在p坐标垂直涡度方程中，利用p坐标向z坐标转换的公式将水平涡度向垂直涡度转化的所有项分离出来，这些项具有明显的斜压特征，对其进行尺度分析后，得出在可以忽略潜热释放对涡度影响的对流层中、高层，此转化项是大尺度斜压涡度发展的重要项。通过对1998年48月的game再分析资料进行实际计算也发现，转化项在东亚夏季风上升支的600hpa及以上层次对垂直涡度的局地变化贡献很大，不能忽略。同时发现水平涡度向垂直涡度的转化在南海季风爆发时和江淮梅雨入梅及发展过程中均有指示性意义，在南海季风爆发以后，在中国东南部地区，转化项的大小与夏季风的活跃和中断等活动有着几乎一致的变化规律，这从侧面也指出了，此转化项的变化是夏季风演变所具有的本质特征，并且它反映出了西太平洋副高在中国大陆的活动情况。
