Observations of Hailstone Sizes and Shapes from the IBHS Hail Measurement Program: 2012–2014
The Insurance Institute for Business & Home Safety (IBHS) began a field measurement program in 2012 focused on evaluating the compressive strength of hailstones (Brown et al. 2012). Through this program, detailed physical measurements of the major and minor axes and the mass were made for over 2500 hailstones from nearly 30 different parent thunderstorms in the Great Plains of the United States over the past 3 years. In addition, a compressive strength test was performed to evaluate the relative strength of hail. This study leverages this relatively large observational dataset to examine hailstone sizes and shapes to provide a comparison with historical literature. The distribution of measured hailstones ranged from a minimum diameter of 3 mm to a maximum of 106 mm. A subset of over 500 hailstones collected during the 2014 field phase featured measurements of the major and minor diameters as well as a third intermediate dimension. This information is used to further characterize the shapes of measured hailstones beyond the axis ratio.