ON THE PHENOMENON OF THE COLORED SUN, ESPECIALLY THE "BLUE" SUN OF SEPTEMBER 1950
AIR FORCE CAMBRIDGE RESEARCH LABS HANSCOM AFB MA
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The phenomenon of the colored sun and moon of September 1950 was explained by utilizing Mies theory of large particle scattering. The particles were attributed to the smoke generated by large forest fires in Alberta, Canada. The radii and concentration of the particles were calculated to be between 0.5 and 0.8 Mu and between 175 and 127 particlescu cm, respectively. The total amount of smoke was calculated to be about 4.7 to 6.5 x 10 to the power of 7 particlessq cm column. A uniform-size and 2 Gaussian distributions were assumed as well as scattering by spherical particles and a refractive index equal to that of water droplets. Calculations of the intensity of the solar spectrum between 3500 and 7000 A, after passage through the smoke lazyer, indicated a pronounced maximum around 4100 and 4600 A in all cases. The physiological impression of such a spectrum was considered to be bluish.