Atmospheric Diffusion in the Range 20 to 2000 Kilometers
It was recently argued on theoretical grounds, by Gifford (1984), that the earth’s rotation should define the outer, or integral time-scale of atmospheric turbulent diffusion, a finding well supported by atmospheric diffusion observations over a wide range of scales (Gifford, 1977, 1983a; Barr, 1983). The consequences of this result, which have so far not been considered in dealing with diffusion at shorter ranges, become important for longer range diffusion problems, beyond about 20 km distance or an hour of diffusion time. In this paper some recent atmospheric diffusion data obtained at long ranges will be compared with earlier data. The form of diffusion in the range 20 to 2000 km, as well as the general nature of diffusion at still larger scales will be briefly discussed in relation to the time-scale of diffusion.
KeywordsPlanetary Boundary Layer Diffusive Motion Relative Diffusion Atmospheric Diffusion Plume Width
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