A general equation for the terminal fall speed of solid hydrometeors

Abstract

It depends on three particle parameters: mass, the mean circumscribed area presented to the flow, and the mean effective projected area presented to the flow. This formula is deduced from a single mean Davies number-Reynolds number relation based on boundary layer theory and therefore includes environmental conditions (air density and temperature). Terminal velocity is predicted with errors ≤10% for a wide variety of particles, e.g., various planar and columnar crystals, rimed and unrimed aggregates, graupel (lump, conical, and hexagonal) and hail up to over 10cm in diameter. -from Author