The cloud seeding technique was accidentally discovered by Vincent Joseph Schaefer (1906-1993) at a
GE lab in
Schenectady. Schaefer was interested in how ice forms on wings as planes pass through clouds. He used a home freezer to create clouds. One day in 1946, he added
dry ice to his "cloud hatchery" to cool the internal temperature down. Much to his surprise, the clouds not only formed, but began to rain. Curious if this could be duplicated in
Real Life, on November 13, 1946 he had a plane fly into a cloud over Mount Greylock,
Massachusetts and seed the cloud with several pounds of dry ice pellets (the term cloud seeding likely got the name because the pellets looked like seeds).
A bit of a joker, Schaefer one day repeated his cloud seeding demonstration for GE
brass, and he was able to get the dry ice pellets to disperse such that they "cut" GE's logo into the cloud on a rather massive scale.
Interestingly enough, Bernard Vonnegut (the brother of author
Kurt Vonnegut) was an associate of Schaefer. He too was interested in the cloud seeding
phenomenon. He suspected that if one could introduce a substance that was molecularly similar to ice, better results could be achieve. A literature search suggested
silver iodide, which did indeed prove to be more effective than dry ice.
Bernard Vonnegut's earlier weather-related work was a project for the Army
Signal Corps, wherein he worked on a project somewhat opposite of creating rain clouds. The Army wanted him to develop a method for clearing fog and overcast skies. This was probably the basis for Vonnegut's famous
Ice-Nine invention in
Cat's Cradle.