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Show f, - fe. 8m - 95" ( 9) where t| is the beginning of the avalanche hazard t^ is the termination of the avalanche hazard and Wl is the snow transport by wind ( gm cm'^ min ) Because this method is simple, reliable ( as justified in practice), and indeed a method of predicting the future conditions, we prefer such an approach for forecasting various types of avalanches in certain regions. Relatively recently. K. L. Abdushelishvi 1 i and V. Sh. Tsomaia ( 1963) proposed a method of forecasting avalanches in the Caucasus which emphasized variations in the relative humidity of the air. As in the method of V. N. Akkouratov, the authors emphasized the empirical aspects of the problem. From their observations, the avalanche hazard almost always arises when the relative humidity attains a steady value of 75%. In order to determine the time of descent of avalanches of freshly fallen snow, they assumed that the critical amount of deposition depends on the thickness of the old snow layer at the moment the relative humidity attains 75%. The authors prepared avalanche forecasts based on the weather forecasts of expected deposition. They established the following empirical dependence for the critical deposition as a function of the thickness of the old snow layer when the relative humidity attains 75% X„= 5- 5- 2. o/ t 7$- ( I") where Xvj is the total deposition necessary for avalanches of freshly fallen snow and h75- is the thickness of the old snow layer on the day before the mean daily relative humidity attains 75%. It is doubtful that this can be considered a fundamental method of forecasting avalanches. In the first place why should the relative humidity be a dependable indication of the avalanche hazard? The data cited by the authors on a graph of avalanche conditions in the winter 1960/ 61 in the region of Krestov Pass show that the moisture of the air attained 75% on 18 occasions; however, in only four cases did avalanches descend. Results of observations from |