As an initial step toward determining the amount of ultra violet light in skyshine and in sunshine it was deemed desirable to determine the ratio of skyshine to sunshine in the visible spectrum. Accordingly readings were taken on a horizontal plane on top of a tall building, once with the test plate of a Macbeth illuminometer exposed to the entire dome of the heavens including the sun and again when the sun was blocked out by an opaque disk. Observations were made every hour on perfectly clear days only.
Proceedings of the Iowa Academy of Science
©1930 Iowa Academy of Science, Inc.
Kunerth, William and Miller, Russel D.
"Skyshine and Sunshine at Ames,"
Proceedings of the Iowa Academy of Science, 37(1), 303-305.
Available at: https://scholarworks.uni.edu/pias/vol37/iss1/73