Light Climate in Moscow

The light climate of Moscow is presented based on the long-term observations of natural illuminance of the Earth’s surface, illuminance of differently oriented vertical surfaces, and factors influencing their variability, which have been performed at the Moscow State University Meteorological Observatory. The obtained normals are sufficient for any practical applications in most cases. An issue analyzed in the study is conditions that lead to a decrease in illumination below the critical values for which the use of combined or artificial lighting of premises is required. It is shown that illumination can be forecasted based on low-level clouds predicted using a general weather forecast.