At head of title: Illinois State Water Survey, Meteorology Laboratory at the University of Illinois. Urbana, Illinois. "July 19, 1961". Final report. "National Science Foundation G-6352". Includes bibliographical references (leaves [2]-[3]) at end.

"The temporal and spatial distribution of giant nuclei in the atmosphere over Illinois was investigated to determine whether their presence was directly related to precipitation processes occurring in that area. A semiautomatic aerosol sampling device was designed and constructed to obtain up to 20 individual samples. A spot test technique was used to determine the chemical types of the particulates captured on a membrane filter. The results of the analyses indicated that the size and number distribution of particulates does not correlate with precipitation occurrences. There is no obvious relationship between the chloride particle concentration and the prevailing air mass type. Certain industrial areas were examined and found to be reasonably good sources of giant hygroscopic nuclei. However, a cursory examination of rainfall records does not indicate that they are important in modifying the precipitation patterns in the vicinity of the sources."--Abstract.