Hi Ladies and Gentlemen Watching an episode of Mythbusters a couple of weeks ago, . . it just hit me .. maybe this is how ice is formed in clouds. You have a supercooled bottle of waterbased liquid. You strike a blow to the bottle and watch the liquid turn instanly into ice. Is not it possible that the sonic boom of lightning would cause the supercooled rain drops to turn to ice. ? ? If so, this explain why hail is usually all of a uniform size. If so, this might explain the colours you see in clouds when the lightning lights them up - either a pinkish or greenish hue - because some wavelength might be used up in the change of state (liquid to solid) of the rain drops.