FISSION PRODUCTS OVER THE PACIFIC NORTHWEST MW ee cml — 435 eTTTT TTT TTT?) TT ene © STRATOSPHERIC SAMPLES = O TROPOSPERIC SAMPLES Fig. 7—Ratios of “Mn/'"Cs activities in stratospheric and tropospheric air samples. was produced in relatively large quantities in the 1961 and 1962 tests. The maximum is probably due to the late arrival of this radionuclide from higher altitudes.