What weather conditions separate rain from hail and hail from snow?
Michael Manzella, Chicago
Rain is precipitation that reaches the ground as liquid water and does not freeze as it makes contact. If it freezes, the precipitation is called freezing rain. Hail is concentric pellets of ice that occurs mainly in thunderstorms. It forms when raindrops are carried into sub-freezing air and freeze, then are again coated with water that freezes once again. The process may repeat several times. Sleet is frozen raindrops that reach the surface. Rain falls through sub-freezing air and freezes. Snow consists of ice crystals that form in the atmosphere at sub-freezing air temperatures and fall to the surface. Hail, aloft, usually melts into raindrops before it reaches the ground, but occasionally falls to the surface.