Fraunhofer Line Filling In (3855–1455 Å)

Noncoherent scattering of solar radiation, resulting in the filling-in of Fraunhofer lines, has been observed in the day sky spectrum from 3855 to 4455 Å. The filling in shows a continuous and almost constant effect over the wavelength range covered, although there is a tendency for the magnitude to decrease at shorter wavelengths. Observations taken over different terrains and at different times of the day and year show that the filling in tends to be higher for a high ground albedo in winter and for small solar zenith angles.