What's the difference between hail, ice pellets and sleet?
Hail and ice pellets are both produced by thundershowers, specifically the repeated freezing of rain drops in the updrafts and the addition of new liquid water in the downdrafts. Ice pellets become hail when they reach a diameter of 1/4" or more. Sleet, on the other hand, forms when rain drops fall through much colder air and freeze. Freezing rain, by the way, occurs when the rain drops don't freeze until they hit the ground...which is at or below freezing.