Abstract
In this paper the author treats theoretically how the essential feature of the atmospheric diffusion appears to be remarkably dependent upon the duration of time T* during which the phenomenon is observed. T* is called the averaging time. This problem is considered in view of extending the author's previous study, in which only the case of T*=∞ was discussed. The most important difference between the present and previous considerations is that in the present one, the eddies smaller than those of a certain scale related to the averaging time only are considered to be relatively effective for the turbulent diffusion, while in the latter all eddies were considered to be so irrespective of their scale.
