The great hail war
If you're stuck in a car during a hailstorm, the racket may be enough to make you think you're in a war zone. Indeed, humans have treated hail as if it were a living, breathing enemy. Europeans of the 1800s fired rockets and cannons at hailstorms, hoping to either deflect the storm or break its hail into less damaging fragments. A more scientific approach was adopted shortly after World War II, when cloud seeding showed promise as a way to reduce hail damage. The idea was to drop huge quantities of silver iodide from aircraft into the parts of a storm laden with supercooled water. Ideally, the water would freeze on the silver iodide particles instead of on hailstones, thus limiting the hail's size. This sounded good in theory, but the actual effect on hail proved nearly impossible to measure. Hailstorms are so variable to begin with that nobody could say for sure how a given storm would have evolved had it not been seeded. Today, the raindouds above several US states are still being seeded to reduce hail, despite the lack of published evidence to support this technique.