Thesis (Ph. D.)--Johns Hopkins University, 1914. / Vita. Reprinted from the Physical review, second series, vol. v, no. 3, March, 1915.

Thesis (Ph. D.)--Pennsylvania State College, 1933. / Cover title. "Bibliography on amplifiers": p. 8.

A method for determining percent cloud cover by taking two consecutive images using different color contrast filters, specifically a red filter and a blue filter, is described. This method (RF/BF estimate) involves dividing the "red" image by the "blue" image, pixel by pixel, and determining the percentage of pixels in the resultant image with intensity values of one. This is the percent cloud cover. The RF/BF estimate is based on the different effects of molecule and particle scattering of electromagnetic waves in the visible portion of the spectrum. These two types of scattering, Rayleigh and Mie scattering respectively, are described as they relate to this methodology. The RF/BF estimates are compared to visual estimates of percent cloud cover using the northern portion of 100 Central Florida skies collected during the period from January 28, 1988 to February 25, 1988. A strong correlation r=0.94 was found between the RF/BF and visual estimates. Advantages of the method are discussed along with implications and suggestions for follow-up studies.