空气并不是纯净的,除了组成它的各种气体以外,还有很多的夹杂物。当阳光穿过玻璃窗射入暗室的时候,我们就能够清楚的看到,在阳光照射的途径中,有很多的微粒在活动着。在大气中,各种各样的夹杂物很多,不但在低层的空气里有:就是在高空中也有。这些夹杂物的来源很多,它们的性质也各有不同,但是它们对天气的影响却很大。云、雨、雾等的发生都是由于它们作用的结果。实验证实纯净无尘的空气虽然达到过饱和状态,仍然不会发生水汽的凝结现象,而在大气中,有 The air is not pure, and there are many inclusions other than the various gases that make up it. When sunlight enters the dark room through the glass window, we can clearly see that there are many particles in the sun’s path. In the atmosphere, there are many kinds of inclusions, not only in the low-level air but also in high altitudes. There are many sources of these inclusions, and their properties are also different, but they have a great impact on the weather. Clouds, rain, fog, etc. are all the result of their effects. The experiment confirmed that although the pure dust-free air reaches supersaturation, water vapor condensation will not occur, but in the atmosphere, there are