part of derives from ice mass cloud hail stone 2021-04-14T18:57:18.275Z envoCryo An ice mass which 1) occurs in a ball-shape or irregular lump, 2) has a minimum diameter of 5 millimeters (or 0.2 inches), and 3) is formed within convective clouds. envoPolar Nearly always formed within cumulonimbus clouds. Typically have a diameter ranging between 5 and 50 millimeters.