Comparison Between Size Distribution of Natural Aerosols and That of Radioactive Aerosols in the Atmosphere

Abstract

The size distributions of natural aerosols and those of radioactive aerosols have been determined simultaneously based on mobility measurements on those charged particles. The apparatus is a cylindrical aspiration chamber. In the case of radioactive aerosols, the central electrode of the condenser is essentially a gas flow counter.
The counter covers the size range with approximate limits of 1×10-5 and 0.8×10-6cm in radius. The results indicate that the maximum number concentration of aerosols is located in this size region, and the distributions of radioactive aerosols are shifted toward larger size region compared with those of natural aerosols. This tendency is also marked with a number of measurements of the mean radius obtained by a diffusion battery.
The size distributions of radioactive aerosols computed theoretically from those of natural aerosols are compared with the results obtained by direct measurements. The experimental results agree with the theoretical distribution as a rough first approach. But, the available data seem to indicate that the experimental results are shifted toward somewhat greater sizes than the theoretical ones.