The long-range dispersion of a plume from an isolated point source

The dispersion of the plume from a sulphide smelter at Mount Isa, Australia, has been determined at distances of up to 1000 km from the source. Simultaneous measurements by an airborne correlation spectrometer, flame photometer and aitken counter have allowed accurate determinations of plume width at these large distances. Radiosonde and pilot-balloon data from four positions spanning the region have been used to calculate the trajectories of each of the plumes measured in the study. In each case the measured plume position was in good agreement with the position predicted on the basis of the wind data. A simple model based on the diurnal variation of the structure of the atmosphere, as well as the turning of the wind with height, is shown to account adequately for the measurements of plume width during well-mixed atmospheric conditions at distances of between 25 and 1000 km from the source.