Photoelectric detection of shadow bands

Faint light and dark bands that are seen moving across the face of the earth just before and after the total phase of a solar eclipse are commonly called shadow bands. In anticipation of detecting these bands at an eclipse, the author constructed equipment which can detect very small light variations that are continuously present in sunlight and thus felt to be certainly sensitive enough to detect shadow bands.The equipment consists of a seven channel recorder used for spectral dependence of light variations and an eight channel power spectrum analyzer which displays the dominant scintillation frequencies present.The equipment was taken to the 10 July 1972 eclipse in Nova Scotia where the equipment detected light variations even though shadow bands were not as visible as previously observed. The dominant frequency on both types of equipment was around 6 Hz.