Equations governing the radiance of the sky at a specific wavelength and distance from the sun are stated, and graphs of the Mie scattering coefficient are presented. Observations of the angular distribution of light in the aureole from ¼° to 3° from the solar limb, and of the wavelength distribution from 4500 A to 8200 A were made with a special photographic sky photometer at altitudes from 5420 ft to 12450 ft above sea level. The analysis of the data shows: (1) The Mie particle density decreases exponentially with altitude. (2) Most of the light in the aureole is that which has been scattered by large particles. At 12 000 ft altitude, the radiance 2° from the center of the solar disk is six times the radiance of the Rayleigh atmosphere. (3) The relative density of large particles is greater in air masses which have been in convection over land for several days and in the air behind a warm front than in other systems. (4) An increase in the relative density of large particles seems to be encountered in the jet stream.
GORDON A. NEWKIRK, JR., "Photometry of the Solar Aureole," J. Opt. Soc. Am. 46, 1028-1037 (1956)