On the Turbulent Diffusion in the Atmosphere. (I)

[摘要] The remarkable diffusing power in the turbulent flow is supposed to be caused by the irregular motion of turbulons (ordinarily named eddies) in the flow. Representing the interaction between turbulons by means of the turbulent friction, the relationship between the scale _??_ and the velocity V of turbulon is obtained. From this result, the spectral function of turbulon energy with regard to its own period τ (or the life-time, given by _??_/V) is deduced as follows: F(τ)_??_const.The so-called Lagrangian correlation function R(ξ) (Taylor, 1922) is obtained in connection with F(τ), and finally deduced to R(ξ)=1-(ξ/τ0), where τ0 means the life-time of the largest turbulon. On the other hand, putting the limit of application for the theory of turbulent diffusion, the state of the smallest turbulon is given by ν=_??_∞V∞. The distinct differences between R(ξ) and R(t), the Eulerian correlation function, are made clear. And also the relations between the smallest turbulon in this paper and the smallest eddies in the meanings of Taylor are shown.The practical applications of the results are left for the following papers.

[学科分类] 大气科学