Atmospheric Diffusion of Settling Particles with Sluggish Response

Abstract

A study is presented of the settling of heavy particles in a turbulent medium and quantitatively applied to the lower atmosphere. The response time of settling particles to changes in the velocity of their surroundings is estimated for a wide range of particle sizes and this time is then compared to the period during which such changes may be expected to occur during settling. The reduction in diffusion due to insufficient response time is predicted. If the time of fallout is sufficiently large compared to the particle's response, time, no significant reduction is effected, as had been previously suggested. An attempt is included to numerically predict the diffusion of settling particles.