All methods and instruments currently being used for the physical characterization of hailstones are listed and discussed. Apart from the simpler measurements of diameter, shape, roughness, surface temperature, etc., particular attention is paid to the aerodynamic forces acting on free-falling hailstones and to the way these forces are ascertained. Further paragraphs are devoted to the technique for obtaining thin sections and to their importance in explaining the growth of ice particles. The application of calorimeters and separators in demonstrating the presence of liquid water in the hailstones is also discussed.
All these methods can be used for investigating artificially produced ice particles.