A form of snow made of roughly spherical lumps of ice, 5 mm or more in diameter, formed when a frozen raindrop is caught in the violent updraughts found in warm, wet cumulo-nimbus clouds. As the drops rise, they attract ice, and as they fall, the outer layer melts, but refreezes when the droplet is again lifted by updraughts, often causing the hailstones to show an onion-like pattern of alternating clear ice (glaze) and opaque ice (rime). A hailstone will descend when its fall speed is enough to overcome the updraughts in the cloud. Soft hail is white and low-density as it contains air. See Billett et al. (1997) Weather & Fcst 12, 1 on the prediction of hail size and Gavrilov et al. (2010) Phys. Geog. 31, 5 on hail suppression.