€, * re and ca:culatea as waces of strontium-95 fFaiiout. The caicu:za- mn tior. of fallout sates from the air fiiter data was madd vy acsumia.,; the mean :esidence time in the Lowec atmosphere to be three days. Ten thoucand feet ic estimates to se the avevaze thickness of the aiv tying beiow the catu ovigin. The opservec fallout rate in Pictzoucgn for tne same period of time checks very weli with the calculated rate for Washington, D. C., from the aix filter data. Tabie I, and II give the cesuléz: of similar caicutations for The cheoretica: va: ues ave those caicuiated < is various latitudes. Fe & both mixed fission products and air £ Ltes strontium-9., data for from the model, assumiu, the avesase trogocpheric resiserce time of one month ard of the stratospheric materia. ten yeas. The mean average coucentration in the Lower atmosphere durin, the Last montnc of 195/ and the first few months of 1956 was apout i aicinte sation pes minute pes 1j0 standard cubic meters or 3.25 per stanaaia cuvic foot in the Northern Hemisphere. At chis time tne content of che nines troposphere would have veen rs ‘ Joe Q Minute pes tno..and xtandacd cub ox 3 to 4 cicintegrations per oO expected to be about 15 times this c . feec. ¢ a s ae This wouid be expected or air juct be-ow the tropopause in the hi:ner Levels of che tropospnere. vie umuerstana the broad probiemc of the residei.ce time ana che scavensit., mechanicm for the troposphese. In brief, falsout

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