Any device or process that will cause clouds to empty to rain. The hope that humans might control weather has a long history. Rain, or the absence of rain, can have very serious consequences. As rain comes and goes of its own accord, beyond human control, it can be frustrating. Societies in many parts of the world, particularly those in regions subject to drought or to torrential rain, have sought to control it by various sorts of magic and, latterly, through science and technology. Rain dances by Native North Americans are an obvious example. Medicine men in many places have also used different types of magic to bring rain. In more recent times, charlatans have developed devices to bust clouds. In the early 1950s Wilhelm Reich invented a device that consisted of nothing more than a battery of hollow pipes and tubes. He claimed that it sucked orgone energy out of clouds, causing them to break up and produce rain. He installed five such machines in the United States two in North Carolina and three in Rangeley, Maine; their alleged success established him as a modern rainmaker
There have also been research programs aimed at persuading clouds to let down their water content at selected times and places. When an area has been desperately short of rain for a long time, threatening its agricultural economy, it is frustrating to see clouds form, build up, and then either move off or melt away without rain resulting. The likely explanation for this weather pattern is that the clouds lack nuclei dust or similar particles about which moisture could condense until it forms large enough droplets to overcome the upward convection currents within the cloud and descend as rain. So attempts were made, starting in 1946, to seed promising clouds with very small silver iodide or solid carbon dioxide crystals in sufficient quantity to produce rain. These precipitation nuclei were injected into the clouds from small aircraft, rockets, cannon, or ground generators. The results were mixed. In one particularly successful series of seeding experiments in Florida, three times as much rainfall was obtained from seeded clouds as from unseeded. There is the problem that, if and when one area gains from increased rainfall, a neighboring area may lose. At the other end of the scale, seeding has been used to reduce the effects of too much rain and accompanying wind and to minimize hail.