Fig. 3From: Accurate analytic approximation for the Chapman grazing incidence functionRelative error as a function of the scale parameter for small (dashed) and large (solid) solar zenith angles. Three analytical formulas are compared: a is Eq. (36) obtained in this work, b is the Kocifaj formula (Kocifaj 1996) that shows the best performance among analytical approximations found in the literature, and c is the empirical formula of Green and Barnum (1963); Green et al. (1964)Back to article page