The structure of a hailstone reflects its
growth history. It can be translated through experiments in icing-wind tunnels.
Knowing the shape allows us to deal with free fall, and, based on it, with heat
and mass transfer - which controls freezing. The various facilities used in his
venture will be discussed, together with the ‘New Hailstone Physics’. Thereby a
big factor is played by ‘Spongy Ice’, an ice lattice that is filled with water.
It explains the explosive growth of hailstones.