Data from Vaisala RS-92 GPS radiosonde,and observed by aircraft are analyzed to research the feature of one spring stratiform cloud precipitation of 2009 at Zhangjiakou.Analyses of quasi-saturation areas,potential instability districts and the evolution of the wind field show the weather characteristics of this event.The result shows the reason of the water vapor variation through its transportation,total content variation and uneven distribution along the altitude.Furthermore,comparison between the Vaisala...