Vertical Variability of Night Sky Brightness in Urbanised Areas

Abstract Excessive amounts of artificial light emitted into the lower atmosphere at night have already become an everyday feature of modern urban landscapes, and gradually also a phenomenon associated with areas located outside large human settlements. Urban islands of light have been the subject of targeted research conducted for several decades by scientists representing miscellaneous fields of science. In Toruń, regular research on the phenomenon of light smog has been carried out for several years at a number of sites located throughout the city. Recently, research has been started on the variability of the night sky brightness in a vertical gradient. To this end, repeatable measurements were made at specific altitudes at two locations in the city using a drone with an automatic light metre on board. The values of the night sky brightness thus obtained allowed us to determine its variability in the vertical gradient up to an altitude of 120 m, as well as to test the possibility of using drones in targeted studies of the light pollution phenomenon.