There's a fascinating article on Atlas Obscura which looks at the work of weather modification companies [atlasobscura.com]:
Weather Modification Inc., or WMI, the world’s largest company of its kind, and one of the oldest, started by a group of Bowman, North Dakota, wheat farmers in 1961.
The article looks at the work of the pilots involved, the methods they use, and the evidence for the effectiveness of the approach.