The Growth Rates and Densities of Ice Crystals between −3°C and −21°C

Abstract

Ice crystals were grown in a supercooled cloud at temperatures ranging from ?3°C to ?21°C for periods from 30?40 s to 150?180 s. When the axial dimensions at a given time were examined as a function of temperature, there was a marked maximum along the a axis at ?15°C and a secondary broader maximum along the c axis at ?6°C. The growth of the axial dimensions can he adequately represented by a linear function of time. A power function of time was fitted to the crystal mass growth measurements; these show a sharp maximum at ?15°C and a secondary broader maximum at ?7°C. Crystal bulk densities estimated from the masses and axial dimensions vary with temperature in a complicated way, with a minimum of about 0.4 Mg m?2 at ?5 and ? 17°C, and a maximum of 0.92 Mg m?2(pure rice) at and appear to he independent of time.