The atmosphere in UNIGINE worlds is rendered dynamically with regard to the current rotation of the World light (time of day) and the Scattering mode used. Environment lighting incorporates the sky cube map, ambient lighting, and global reflections. In this video, you will learn how to customize environment lighting.
More on customizing environment lighting in UNIGINE 2: https://l.unigine.com/vUVolkyHP
Download UNIGINE 2 SDK: https://l.unigine.com/2FfBzWpIq