Hautière et al. [8] presented a model to describe the road surface luminance curve. Fitting this model to the reality allowed them to measure atmospheric parameters and, in turn, the meteorological visibility. We introduce a more complex and appropriate model based on the theory of radiative transfer. Through modeling the inscattered light by Koschmieder’s Law and assuming a simple scene geometry we can find a correspondence between the extinction coefficient of the atmosphere and the inflection point of the luminance curve. Contrary to the work of Hautière et al., this relation cannot be formulated explicitly. Nevertheless an approach based on look-up tables allows us to utilize the improved model for a low-cost algorithm.