three methods of cloud seeding

Old-vid., (simple) - R.F. and lasers NOT included! (Dynamic cloudseeding= fun)

There are three cloud seeding methods: static, dynamic and hygroscopic.

Static cloud seeding involves spreading a chemical like silver iodide into clouds. The silver iodide provides a crystal around which moisture can condense. The moisture is already present in the clouds, but silver iodide essentially makes rain clouds more effective at dispensing their water.

Dynamic cloud seeding aims to boost vertical air currents, which encourages more water to pass through the clouds, translating into more rain [source: Cotton]. Up to 100 times more ice crystals are used in dynamic cloud seeding than in the static method. The process is considered more complex than static clouding seeding because it depends on a sequence of events working properly. Dr. William R. Cotton, a professor of atmospheric science at Colorado State University, and other researchers break down dynamic cloud seeding into 11 separate stages. An unexpected outcome in one stage could ruin the entire process, making the technique less dependable than static cloud seeding.

Hygroscopic cloud seeding disperses salts through flares or explosives in the lower portions of clouds. The salts grow in size as water joins with them. In his report on cloud seeding, Cotton says that hygroscopic cloud seeding holds much promise, but requires further research.

­China has a reputation for launching ambitious projects, from the Great Wall in ancient times­ to the highest railroad in the world, connecting Qinghai to Tibet. But is the investment in cloud seeding worth it, and can the government really make it rain whenever it sees the need? On the next page, we'll look at some of the criticism surrounding cloud seeding.

http://science.howstuffworks.com/nature/climate-weather/meteorologists/cloud-seeding1.htm