Sky Brightness and Cloud Cover at Several Locations Across Missouri

We present an analysis of zenith sky brightness data from five different locations across the state of Missouri using Unihedron Sky Quality Meters (SQM’s). This work is part of an ongoing collaborative effort led by members of the Missouri chapter of the International Dark Sky Association and local volunteers from various locations across Missouri. This arrangement allows for data to be collected in locations with varying levels of light pollution, ranging from heavily polluted urban areas to relatively unpolluted semi-rural areas. We combine the SQM data from each location with cloud cover data obtained from a nearby airport to measure the effect of cloud cover on the sky brightness at that location. We find that the difference in sky brightness between cloudless versus cloudy nights is strongly correlated to the level of ambient light pollution at a given location, ranging from a dramatic 3.7 +- 1.4 magnitudes per square-arcsec (higher levels) to 0.5 +- 0.7 magnitudes per square-arcsec (lower levels of light pollution). We use this correlation to develop a predictive model for the effect of cloud cover on sky brightness under differing levels of ambient light pollution.