Measurements of Local Density in Artificial and Natural Hailstones

Abstract

Local density measurements were performed in the internal structure of hailstones by means of photometric observations on x-ray micrographs of thin slices. Comparison with the results of measurements performed by the same technique on ice artificially grown by accretion shows that dry growth near the net limit or dry growth wetted in a final stage is probably the most common condition of growth in natural hailstones. The technique is also suggested as a method for obtaining accurate quantitative data an air bubble size and concentrations which are needed in relating structure to growth conditions,. As a cross check, measurements of the total density by the usual immersion technique were also performed on hailstones from the same hail-fall as those examined by the x-ray absorption technique.