Originally Posted by Tainui

I've seen those hail cannons in action in the apple orchards of South America. I'll look for the video and post it. Pretty cool system really.

The premise is to fill an iron chimney with propane and then ignite it. Think artillery simulator and it sounds just like a howitzer firing. In person, I could see the shockwave exit the cannon and disperse into the air. It supposedly shatters the hail stones into harmless pieces.