The 1908 Tunguska event and the atmospheric optical anomalies

Abstract: This paper is a continuation of a series of works, devoted to various aspects of the 1908 Tunguska event. In the late June - early July, 1908 there were various optical anomalies in the atmosphere. Early the Author already considered "bright nights", and in this paper some other atmospheric optical anomalies are considered, such as prolonged twilights, etc. Much attention is paid to the review of works on the study of atmospheric transmission at the Smithsonian Astrophysical Observatory in 1908. The main features of the atmospheric optical anomalies and their consequences for the interpretations of the Tunguska event are described. It is shown that neither the asteroidal nor the cometary interpretation of the Tunguska event is consistent with the anomalies. The geophysical interpretation can explain the atmospheric optical anomalies at the qualitative level at least. Quantitative explanation is currently difficult due to limited observational data and the lack of clarity in the details of physical phenomena.