RADIOACTIVITY AND POTENTIAL VORTICITY \ 443 | 4000 > P FILTER PAPER Zz = 3000 |- CHANGED o z A 8 fr ! Sf 100 o~AN > 70 O 80 é 5 2000 -— 70 a < 50 3 —-34 = ar Y a a T a 40 Z — -36 30 = 4-38 1000 t— 20 «4-402 —+-42 8 ~~" — 44% = 4-462 —! -48 0 19 TIME, Z Fig. 5—-Wind speed, temperature, and accumulated radioactivity re- corded by WB5O0 aircraft (see Fig. 4. Apr. 18, 1963, at 23,000 to 27,000ft. The slope of the accumulated radioactivity was not as steep as during the first transit. It was on the second transit that the filter sample was taken which gave a total beta count of 136 dis/min per standard cubic foot. On the first transit, values of 200 dis/min per standard cubic foot would be expected from the accumulation rate. In Fig. 6 the Sr activity in disintegrations per minute per 1000 scf are plotted against the distribution of potential vorticity. This distribution was tediously calculated by hand from the © and isotach analyses of Fig. 4. The distribution is presented as calculated, but no claim is made for accuracy of the details. Maximums and minimums may be shifted by slight changes in the original analyses, but the general pattern cannot be significantly altered. The numerical correspondence between the Sr activity and P,/g is remarkable, It lends support for the assumption of a positive correlation between radioactivity and potential vorticity. It also implies that the radioactive layer in the troposphere extends to the 500-mb, or 18,000-ft, level. Unfortunately, no measurements were made below 27,000 ft to confirm or refute this implication.