Based on many years of measurements and observations on the frequency and intensity of deposition of various types of rime which have been conducted by the Department of Meteorology and Climatology of Wroclaw University at the top of Szrenica, Sudety mountains, a hundred meters above the tree line, the essential factors influencing this feature have been determined and are discussed. The upper parts of the Sudety mountains belong to the regions with the most frequent and heaviest rime deposits in Europe, which often appears to be hazardous to farming. It has been found that intensity of rime deposition depends clearly on air temperature and wind velocity, and it is related to certain types of weather situations characterized by types of atmospheric circulation delineated by Konček and Rein (1971).