Some Remarks on the Vertical Diffusion of Smoke near the Ground

Abstract

The author deals with the vertical diffusion width of smoke in the wind near the ground. At first the diffusion phenomena are clearly separated in two states, i.e., the transient and the ultimate state, and also in two zones, i, _??_., the I-class and the II-class zone. These separations are shown to be possible by means of the mutual comparisons of the Lagrangian averaging-time and the life-time of the absolute largest turbulon in the flow, and also of the Lagrangian process-time and the life-time of the effective largest turbulon.
As to the ultimate state of the vertical turbulent diffusion of smoke near the ground, the theoretical results are compared with recent F. A. Record's (1951) experimental ones in general agreements.
On the other hand, concerning O. G. Sutton's (1951) recent question about the interrelation between the smoke width and the averaging-time the author presents a certain reasonable explanation making use of the concept of the transient state of vertical diffusion.