The atmospheric transmittance and the astronomical refraction for low-elevation trajectories are discussed and quantitatively developed. The results are used to describe and calculate some of the fascinating atmospheric phenomena occurring shortly before and during sunset, such as the diminishing apparent luminance of the sun, its shape during sunset, and the green flash.
© 1980 Optical Society of America
M. Menat, "Atmospheric phenomena before and during sunset," Appl. Opt. 19, 3458-3468 (1980)