620 VOLCHOK these data, although some specific oscillations should be mentioned, For instance, at Chacaltaya a peak in July or August seems to appear quite regularly, whereas at the three southernmost sites, Santiago, Puerto Montt, and Punta Arenas, a peak in the early part of each year seems to appear. These variations are believed to be quite significant and will be referred to again in a later section. 89¢r/390Sr RATIO IN GROUND-LEVEL AIR A broad impression of the homogeneity of the ground-level air in 1963 can be gained by study of the "*Sr/*Sr ratio measured in 80th meridian samples. Figure 4 is a plot of this ratio for sites in the northern hemisphere. Also included on the graph are data from a few PO 50 E | . rs a 10 T wv \ TY AIR-FILTER SAMPLES © THULE AND MOOSONEE (50 AND 80°N)-4 ; ¥ WASHINGTON, D.C,AND MIAMI (20 AND 40?N) 7 a SAN JUAN AND MIRAFLORES 4 (0 AND 20°N) % MAUNA LOA (19.5°N, ~11,000 FT) RAIN SAMPLES \ @ WESTWOOD, N.J. © @ RICHMOND, CALIF. NG SEATTLE, WASH. _ — pe — 2 < \B L 3s” NN Za Ww i & g Q ¥ ~ L 7 4 Ns %5°/%s DECAY co — ; a = 3 & — 0.5 oN 4 — a7 \ eo toy et eg JAN FEB MAR APR MAY JUN JUL AUG SEPT OCTNOV DEC Fig. 4—"Sr/?Sr in air and precipitation in the northern hemisphere in 1963,

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