Abstract: More than three years of 3-hr high-contrast whole-sky photographs, sky-cover observations, and cloud-type observations were utilized to develop two methods for estimating cloud-free line-of-sight probabilities through the ...

Abstract: Relative frequencies of cloud-free lines-of-sight were determined at specified elevation angles and directions by utilizing data from photographs taken with a camera with a 180° (fish-eye) lens and infrared film to produce ...

Abstract: Effects of sky cover variations on daylight total hemispheric radiation were determined from measurements made at Columbia, Mo. Total hemispheric radiation was measured by a Beckman and Whitley radiometer, solar radiation ...