Turbulence Damping and Drag Reduction Produced by Certain Additives in Water

TLDR: In this paper, the U.S. Naval Research Laboratory has published data on gross beta and strontium-90 activity in ground-level air along the 80th meridian West I957-62.

Abstract: seasonal variations in the air activity ratio may then be connected with the variations in the precipitation ratio and in the wind variability. The apparent connexion between air activity and precipitation in Norway makes it of interest to look for similar tendencies in more world-wide observations. The U.S. Naval Research Laboratory has published data. on gross beta and strontium-90 activity in ground-level air along the 80th meridian West I957-62 (ref. 2). The strontium-90 activity at the measuring stations in the northern hemisphere follows the same overall seasonal pattern as shown by the ca.esium-137 concentration in Fig. 2A. The precipitation in the northern hemisphere also shows a seasonal variation, with a minimum in spring and a maximum in autumns. The data in refs. 2 and 3 thus indicate a correlation between air activity and precipitation in the northern hemisphere similar to that of the model in Fig. I. From ref. 2 it seems that the spring peaks in the northern hemisphere tend to appear later at 39° and 51° than at the stations north and south of these latitudes. The minimum in mean precipitation as estimated in ref. 3 also appears later in the middle latitudes. This apparent correlation may be due to the larger exchange of air in zonal than in meridional direction in the troposphere. It might then be expected that latitudinal variations in precipitation would lead to latitudinal, inverse variations in air activity. Such an effect might be deduced from Fig. 4. Curve A shows mean annual precipitation (December-November) from 5° N to 90° N, based on ref. 3. Curve E, which is the most complete Naval Research Laboratory profile available over 12 months, shows the average beta activity in air over the period December 1958 to November 1959 at six Naval Research Laboratory stations. A seasonal variation in the latitudinal distribution of precipitation is evident from curves Band 0. In December-May there is a precipitation minimum at 15°-20° N. In June-November the minimum is found at 30°-35° N. It appears from curves D and F that there is a corresponding shift of the air activity maximum from around 25° N in December 1958-May 1959 to around 40°-50° N in June-November 1959. Summarizing, it may be said that seasonal and latitudinal variations in ground-level air activity appear to be correlated to seasonal and latitudinal variations in precipitation. It is realized that other geophysical processes also cause variations in air activity. However, the effect discussed in the present article seems to form a necessary part of the complete fall-out picture.