THE SIZE DISTRIBUTION AND AGING OF NATURAL AEROSOLS AS DETERMINED FROM ELECTRICAL AND OPTICAL DATA ON THE ATMOSPHERE

Abstract A first attempt at surveying the complete size distribution of natural aerosol particles is made. The size range covers more than three orders of magnitude in radius, with approximate limits of 2 × 10−3 and 5 × 10−7 cm. Previously only parts of this spectrum had been carefully investigated, due to the size limits of the various experimental methods used. Particle spectra down to radii below 10&-4 cm are well known, having been obtained by direct count under the microscope. Particles of radius less than 10−5 cm are counted in the Aitken counter, but their size distribution can only be determined from mobility measurements on those particles which are charged. However, to deduce nuclei spectra from ion spectra, the fraction of charged particles must be known. Previous determinations of this fraction are examined and are shown to contain inaccuracies or errors. The expression derived here theoretically, is used to convert some of the ion-spectra data into nuclei spectra. The particle-size range betw...