Cloud seeding is a form of weather modification which involves the introduction of silver iodide (or sometimes dry ice) into the clouds to activate the formation of precipitation in the form of rain or snow. Cloud seeding has evolved over the years and scientists now know more about the process and what works and what doesn’t.
The technology of seeding clouds was introduced 70 years ago by the experiments of Vincent Schaefer. In 1946, this self-taught chemist seeded clouds over the mountains of Massachusetts with six pounds of dry ice. This experiment resulted in snowfall. Since then, his experiment has led to the belief that cloud seeding could be an answer to the ongoing problems of drought, control of forest fires, control of mega storms and the reduction of damaging hail.
Los Angeles County has attempted to increase precipitation by using cloud seeding since 1950‘s. In the recent rainfall in early March, 2016, clouds were seeded over Los Angeles. This was the first cloud seeding in LA done by the Department of Public Works since 2005.
How Is Cloud Seeding Done?
There are a couple ways to seed clouds. One way is via an airplane flying into the clouds with flares on the wings to release aerosolized silver iodide to stimulate rain and snow. Another way is using generators, which resemble mini missile launchers that sit on the ground and shoot silver iodide smoke into the clouds. The particles in the smoke attract water vapor which freeze onto the particles. When the frozen particles become heavy enough, they fall as rain.
Is Cloud Seeding Safe?
Because the small amount of silver iodide that is used, it is generally conceeded that cloud seeding does not harm the environment. According to the Centers for Disease Control and Prevention, “there is no reason to fear any toxic effects.”
Does Cloud Seeding Really Work?
The process of cloud seeding has improved over the years, but there is a difference of opinion as to whether or not cloud seeding really works, and if there are any long-term negative repercussions on the environment from the use of this process. In an article published in the LA Times, the Los Angeles County officials stated that their studies show that cloud seeding results in about a 15 percent increase in rainfall. However, there is is some disagreement coming from the scientific community regarding this figure. To quote from Lynn Russell of Scripts Institute’s Department of Atmospheric Chemistry, “there is no scientist who actually thinks that cloud seeding works.” She stated in an interview with NBC San Diego, that “there is has been no scientific increase in rainfall totals when seeding techniques are used.” In addition, there are still questions about how much extra precipitation seeding actually creates. The Desert Research Institute of Nevada has estimated that cloud seeding has produced an increase of ten percent in the snowpack. However, in 2013, the California Department of Water Resources issued a report that stated that cloud seeding only produced an average snowpack of four percent.
The Future of Cloud Seeding
Cloud seeding programs across the country are awaiting the completion of a 13 million dollar study started in 2005 by the state of Wyoming. This is the first truly exhaustive, in depth study of the technology. It will attempt to determine whether or not cloud seeding will increase the snowpack in the state’s mountain ranges. It is believed by many in the field that this study will bring new credence to the process.
However, Robert Moore of the National Resources Defence Council (NRDC) states that “the efficient use of water is the cheapest and most reliable way of making more of it available for future use.”