Scripps Institution of Oceanography

SIO Reference 61-1. Certain optical measurements of the atmosphere were made by the Visibility Laboratory of the University of California, San Diego, 21 June 1958, over central Minnesota. Data were recorded from daybreak to midmorning during the time four balloons carrying optical instrumentation from the Geophysics Research Directorate, Air Force Research Division, Bedford, Massachusetts, were floating at a higher altitude.