/kloc-within 0/hour. One kind of artificial rainfall is to spread the coolant such as dry ice into the cloud by plane, which makes the temperature in the cloud drop significantly, and the tiny water droplets and ice crystals increase rapidly, forcing them to drop and forming precipitation. The other is to use rockets and shells to shoot chemicals into the sky, bombarding clouds to produce powerful shock waves, so that cloud droplets collide with each other and merge into raindrops to land. Artificial rainfall in Nanning will stop within an hour. According to the physical characteristics of different clouds, the method is to choose the right time to spread dry ice, silver iodide, salt powder and other catalysts into the clouds by planes and rockets to make the clouds precipitation or increase precipitation, so as to alleviate or alleviate farmland drought, increase irrigation water or reservoir water supply capacity, or increase power generation water.