On the whole, amount of precipitation received at land stations 

 is rather uniform, which is as might be expected in countries of 

 monotonous relief. This is especially true in the north central 

 portion of Siberia. Variation of the annual amounts from year 

 to year is also slight. Snowfall varies more than rainfall, espe- 

 cially where it is comparatively scarce. Depth of snow for any 

 month may exceed four times the average fall, whereas rain seldom 

 exceeds twice the normal amount. 



Although the amount of precipitation along the arctic coast is 

 small, the ground remains soaked for a long period in summer. 

 Underground drainage is prevented by the permanently frozen 

 subsoil. Even though somewhat larger amounts of precipitation 

 are received farther south at inland stations, the summer tempera- 

 tures are so much higher that drought conditions become manifest. 



The amount of precipitation decreases considerably toward the 

 North Pole, especially in winter. In precipitation, as in tempera- 

 ture, interzonal differences are apparent. In the Canadian archi- 

 pelago and on the north coast of Asia summer precipitation is 

 greater than that of winter, but in the North Sea low pressure 

 area, between the east coast of Greenland and Novaya Zemlya, 

 averages are greater in winter than in summer. In the region of 

 the foregoing low and the low pressure spur in Baffin Bay the 

 annual amounts of precipitation are greater than in the other 

 regions of equal geographical latitude. 



Snow may fall in every month and rain falls only in June, July, 

 August, and September. May has, on the whole, the greatest 

 number of days with precipitation and the midwinter months the 

 smallest. The contrast between conditions in summer and winter 

 appear to be greater over the pack ice than at the coast. 



No diurnal variation was found in winter in the pack ice but in 

 other seasons of the year the probability of precipitation appears 

 to be greater at night than in the daytime. The difference is 

 especially great in spring, but apparently there is no satisfactory 

 explanation of this feature. It was also found that the proba- 

 bility of precipitation was greater with northerly than with 

 southerly winds. This is also true of the coast as the land eleva- 

 tions would favor precipitation with onshore winds. 



The frequency of precipitation varies, in general, with the total 

 precipitation. Koeppe suggests that at least two-thirds of the 

 Dominion of Canada probably has fewer than 80 days per year 

 with measurable amounts (0.01 inch or more) . This area embraces 



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