While reading the latest issue of Weatherwise, I learned that The Desert Research Institute of Nevada has been conducting experiments using a drone for cloud seeding.

https://www.engadget.com/2016/05/04/cloud-seeding-drone-makes-first-flight-over-nevada/

This is surprising considering that many cloud seeding experimental programs were suspended following The Rapid City Flood in June 1972. Cloud seeding was being conducted nearby at the time.

http://www.weathermodification.org/publications/index.php/JWM/article/viewFile/166/212

Weather modification is a double edge sword and results have been dubious at best. In 1972, there were lawsuits against those that were conducting cloud seeding near Rapid City, even though there was little evidence that cloud seeding had augmented the rainfall that caused the flooding.

Penn State had also been conducting similar experiments in the seventies with their own aircraft. That program was also suspended. The plane that was being used for weather modification was refitted for air pollution studies.