The Contribution of the Intensity in Scattered Light of Each Wavelength to the Sky Light at Sunrise and Sunset

Abstract

The contribution of scattering received at the earth's surface from any point in the atmosphere has been found to obey some rules.
In the primary scattering, irrespectively of direction, the intensity generated by the higher atmosphere is predominant in the longer wavelength. The intensity is maximum in the sun's direction and minimum in the direction rectangular to it, being intermediate between both extremities in anti-solar direction, in constant altitude and wavelength. It diminishes with increase in altitude and becomes minimum in zenith, in constant azimuth and wavelength.
The intensity of secondary scattering received at the earth's surface from any point in the atmosphere generated by the primary scattering coming from all directions is predominant in shorter wavelength in higher atmosphere and at larger altitude.
The partial intensity for each wavelength increases progressively with decrease in elevation in every direction. It decreases with increase in altitude for each azimuth and elevation.
The partial intensity for each wavelength is maximum in the sun's direction and minimum in the direction rectangular to it, being intermediate between the two in antisolar direction at constant altitude. It . decreases with increasing altitude in each azimuth. The position of the wavelength in which the maximum value takes place for each azimuth displaces to the shorter at larger altitude.
The partial horizontal scattering intensity is maximum at the shortest and decreases monotonously with increasing wavelength.