Hailstone Shapes

Abstract Hailstone growth results in a variety of hailstone shapes. These shapes hold implications for modeling hail processes, fall behaviors including speeds, and remote sensing signatures hail. This study is an in-depth analysis natural shapes, using large dataset hailstones collected the field over 6-yr period. data come from manual measurements with digital calipers three-dimensional infrared laser scans. Hailstones tend to have ellipsoidal geometry minor-to-major axis ratios ranging 0.4 0.8, intermediate-to-major between 0.8 1.0. suggest are better represented as triaxial ellipsoids opposed spheres or spheroids, which commonly assumed. The scans allow precise sphericity measurements, first time. become increasingly nonspherical increasing maximum dimension, typical range values 0.57 0.99. were used estimate drag coefficient, was found 0.5 0.9. dimension tends be 20%–50% larger than equivalent-volume spherical diameter. As step toward understanding quantifying this may aid parameterizations models detection sizing algorithms.