There is an operation in Calgary that seeds clouds in the Spring and early Summer as a method of controlling hailstorms. The purpose is to provoke precipitation prior to the hailstones getting to the size where they cause damage. They use a light twin to seed. I heard it was funded by a group of insurance companies. They have had some fairly major incidents of damage in the past.
See link below
http://www.bbsr.edu/rpi/meetpart/nov00/smith/
Regards