February 11, 1916] 



SCIENCE 



213 



discussion with maps of the snowfall of the 

 eastern United States was published by C. F. 

 Brooks in the Monthly Weather Review, June, 

 1914, and January, 1915. 



Snowstorms of the eastern United States are 

 difficult to forecast, because a sleet or ice storm 

 frequently occurs instead. Professor H. C. 

 Frankenfield, of the Weather Bureau, has re- 

 cently made a study of the temperatures pre- 

 ceding sleet and snow storms."^ Steep tempera- 

 ture gradients northward, and high tempera- 

 tures over the Gulf and south Atlantic states 

 are necessary for sleet formation and usually 

 absent before and during heavy snows. 



The heavy snowfall problem in mountains of 

 the west is discussed by A. H. Palmer in a 

 well-illustrated paper, " The Region of Great- 

 est Snowfall in the United States." - 



Tamarack, and Summit, California, have 

 the greatest observed snowfall in the United 

 States. 



are steep to prevent similar crushing.^ For 

 thirty-two miles, from Blue Canyon to 

 Truckee, expensive snow sheds are required to 

 protect the Southern Pacific tracks from the 

 snowfall and avalanches. 



Momitain snowfall is of immense value for 

 water power and for irrigation; and to some 

 extent this value is controlled by the rate of 

 melting. Messrs. A. J. Jaenicke and M. H. 

 Foerster have written an article on " The In- 

 fluence of a Western Yellow Pine Forest on 

 the Accumulation and Melting of Snow." ^ 

 Five years of records near Flagstaff, Arizona, 

 indicate that the snowfall in the forest and ad- 

 jacent grass and farm land park is same; but 

 that the rate of melting is different. In the 

 park the minimum temperatures are lower and 

 the maxima are higher than those in the for- 

 est. Thus the soil in the park is generally 

 frozen before the winter snow cover is estab- 

 lished, while in the forest the soil may freeze 



During heavy snowfall the wind is usually 

 relatively light, in marked contrast to the 

 windy snowstorms of the east. The pressure 

 of the snow on any raised objects becomes very 



DEPTH OP SNOW ON GROUND (9-YI:AR AVERAGE) 



(inches) 



A fence made of two-inch boiler flues 

 has been bent; the snow sheds, even where 

 built of twelve- by fourteen-inch timbers occa- 

 sionally collapse, and the gables of the houses 



1" Sleet and Ice StoTms in the United States," 

 Second Pan-American Scientific Congress. 



2 Mo. Weather Bev., May, 1915. See map of 

 the snowfall of the United States by C. F. Brooks, 

 Qiiar. Jour. Hoy. Meteorological Soc, April, 1913. 



only in a few spots. Any water from melting 

 snow in winter forms an ice layer at the base 

 of the snow cover in the park, but sinks into 

 the ground in the forest. In winter on ac- 

 count of the generally higher temperatures and 

 the heating of the local bare spots and trees, 

 the snow melts more rapidly in the forest than 

 in the park. In spring, on the contrary, the 

 formation of slush, the strong sunshine, and 

 higher wind velocity in the park cause the 

 snow to melt a week, or even more than two 

 weeks, before the last drifts of snow in the 

 forest. The frozen soil and the basal ice layer 

 in the park allow the water to run off very 

 rapidly, while only occasionally is there any 

 surface run-off in the forest. The value of 

 open forest for water conservation is evident. 



3 Note the destructive effect of the heavy snow- 

 fall at Flagstaff, Arizona, December 29-31, 1915. 

 *Mo. Weather Bev., March, 1915. 



