A physical effect (optical effect), which may be observed in solar irradiance as shading due to a cloud passing overhead may be approaching a given location (e.g., a location at or proximate a solar power generator), has been discovered. This optical effect takes place prior to an occurrence of a solar obscuration event by the cloud, and thus this optical effect may be effectively sensed and processed in apparatuses, systems and methods to predict the occurrence of a solar obscuration of the power generator.