ABSTRACT
Observations of a smoke plume in the atmosphere show that its instantaneous structure is “puffy” with wide sections interspersed between narrow ones and that the plume meanders in a highly variable manner. Such variability is caused by the randomness of the turbulent wind field in which the plume is embedded. The turbulence is produced by wind gusts or mechanically generated “eddies” due to flow over the rough ground and, during daytime, by warm convective plumes or thermals rising from the heated surface. The turbulence exists primarily in the lowest part of the atmosphere known as the atmospheric boundary layer (ABL), which typically extends from 1 to 2 km above the surface during the day and from a few tens to a few hundreds of meters at night. Since dispersion is driven by turbulence, one needs information on the ABL turbulence properties in order to estimate dispersion.
