Pat Shingleton: A Hail of A Blast
In 1907 the Italian Royal Academy of Sciences noted that tests of anti-hail cannons weren't effective and urged the government to cease encouraging expensive and useless work. By the early twentieth century, anti-hail cannons disappeared. Replacing them were rockets that would explode 800 grams of dynamite, above the ground, to prevent hail formation. The explosions caused cold core eddies that develop hail to break up. The rockets were in conflict with safety measures designed by civil aviation. In 1972, the French company, Corballan, marketed a new version of the hail cannon and remains the largest manufacturer. The new cannons substitute acetylene for black powder, automatically load and reload and are fired from remote locations.