Insoluble Particles in Hail and Rain

View More View Less
  • 1 National Center for Atmospheric Research, Boulder, Colo.
© Get Permissions
Full access

Abstract

Varying concentrations of different sized, solid, water-insoluble particles in rainwater and hailstones collected during thunderstorms indicate the existence of several scavenging mechanisms of micron-size particles. It is shown that Stefan flow is probably the predominant mechanism of in-cloud scavenging of particles 1.5–5 μ in diameter when solid (ice crystal) and liquid (supercooled cloud droplet) phases are present simultaneously. Particles larger than 5 μ in diameter were scavenged primarily by impaction. On many occasions, concentration of particles larger than 100 μ diameter in rainwater was found to be inversely proportional to rainfall intensity. Studies of spatial distribution of solid particles in hailstones should be supplemented by isotopic analysis.

Abstract

Varying concentrations of different sized, solid, water-insoluble particles in rainwater and hailstones collected during thunderstorms indicate the existence of several scavenging mechanisms of micron-size particles. It is shown that Stefan flow is probably the predominant mechanism of in-cloud scavenging of particles 1.5–5 μ in diameter when solid (ice crystal) and liquid (supercooled cloud droplet) phases are present simultaneously. Particles larger than 5 μ in diameter were scavenged primarily by impaction. On many occasions, concentration of particles larger than 100 μ diameter in rainwater was found to be inversely proportional to rainfall intensity. Studies of spatial distribution of solid particles in hailstones should be supplemented by isotopic analysis.

Save