The sky glow emitted from any city is characterised, in the first instance, by the actions of the individuals living within the community, and all the features that comprise the urban system. The second important factor is the atmospheric optical conditions that cause the light beams to scatter and attenuate along their paths through the atmosphere.

The night sky brightness correlates with different components of the atmos phere, especially with aerosol particles constantly suspended in the troposphere. The aerosol optics and Rayleigh scattering are decisive in forming the sky radiances. However, clouds can significantly change sky radiance patterns. Clouds, containing both natural and artificial aerosols, are the most important atmospheric constituents that modellers need to evaluate in order to provide correct predictions. Therefore, it is of great importance to develop methods that allow us to obtain reliable analyses of the sky glow by considering not only clear sky situations but also the interaction of overcast periods with artificial lighting in nocturnal environments.

The core of this work follows a theoretical approach based on the method of successive orders of scattering (SOS). The concept of SOS was incorporated into more general sky glow model in order to determine the optical behaviour of the overcast sky depend ing on direction of observation. Criteria for selecting types of clouds include long-term observations in Slovakia and weather fluc tuations that are commonly found in México.