To get from the sky and atmosphere drawn by an artist to the image calculated by a physical model, it is necessary to consider many factors. Ignoring even the smallest of them leads to a serious deviation of the visual result from the reality that we observe with our own eyes in real life. The model must take into account the chemical composition of the atmosphere, the distribution of atmospheric parameters by layers, fine suspended particles in the lower atmosphere (dust, rain, fog, etc.), the inclination of the sun relative to the zenith position, the shading of the atmosphere by the Earth’s surface, and much more.