水汽含量或称可能降水量,它所表示的是,若地表单位面积上空气柱内包含的水汽,全部凝结成降水落下所形成的水层深度。大气湿润状况的表示方式很多,但为了作降水的定量计算或研究水汽对辐射的吸收影响等,便需要知道整层大气内的水汽含量。

The monthly mean values of the precipitable water from about 70 radiosonde sta-tions in China have been computed for the period 1957 to 1959, and for each month a chart has been prepared. The distribution and variation of the precipitable water over China is closely sociated with the monsoon system over East Asia. The yearly mean precipitable water decreases from southeast to northwest. The dis-ttibution of precipitable water is influenced by the topography, particularly in summer. The area of maximum precipitabie water occurs in South China in winter and moves to. the lake basins of Tungting and Poyang during the summer months. In winter, except South China, the precipitable water of most of the country is below the normal for the latitude; in summer, the eastern half of China is above the normal, while the west re-mains below. Accordingly, the annual range of precipitable water is largest in the eastern half. The gradient of the precipitable water is larger in summer than in winter.