Originally Posted by
ToiletDuck
It's big in Texas. The state pays them to do this. It isn't really used to produce rain. The goal of it is to reduce hail. They look on radar and if they see hail conditions forming they drop crystals beneath that are sucked up. They act as condensation nuclei and cause the water to form on them and fall before it is able to build up into a massive storm. It's a big deal on coastal areas where we can get tops at 30+k feet. It's actually paid for by the agriculture department on Texas.
Depends on the project. A great deal of the projects in Tejas actually do rain augmentation only, while a select few do hail suppression, from what I've heard from the wx-modders down there. ToiletDuck's description of hail suppression seeding (what I got to do) is pretty accurate. There's also projects in California, and all over the world with Weather Modification, Inc. (WMI hires lots of UND grads from what I've heard).