Observations of the Embryos of Graupel

Abstract

Embryos in natural graupel particles were studied with a setereomicroscope by carefully disassembling samples gathered at two locations globally apart. For the majority of graupel particle clearly identifiable embryos did not exist, suggesting that embryos of graupel occurred as a result of rime breakup. In some cases, ice particles, frozen drops, plates, dendritic crystals, and broken crystals were found as embryos; the minimum sizes of embryos of graupel were 0.3 mm (dendritic crystal) and 0.1 mm (others). Isometric crystals, which show a high probability of growing into graupel due to their fast fall velocities, were also confirmed as being embryos of graupel.