566 



SCIENCE 



[N. S. Vol. XLVII. No. 1223 



from western Tennessee to soutliern Ohio 

 where the snow was deep at the time. One 

 Weather Bureau observer in West Virginia 

 reported a minimum of — 37° F. ; and another 

 in Iowa, — 40°. Extreme minima, — 45° F., 

 established new low records for South Dakota 

 and Maine. On January 12, "that cold 

 Saturday," a true blizzard with snow driven 

 by a gale at a temperature down to 20° below 

 zero (F.) tied up traffic almost completely for 

 two days in the Middle West. 



Eelative to the cold land or snow surfaces, 

 the open waters of the Great Lakes, Atlantic 

 and Gulf were excessively warm; therefore 

 they favored the development of numerous 

 cyclones — some of them very intense. These 

 supplied the snow which blockaded the rail- 

 roads, or the rain which produced such disas- 

 trous floods in the ice-gorged rivers.- In the 

 immediate vicinity of the Great Lakes, snow 

 fell almost daily in January; and with many 

 heavy falls, reached totals of 3 to 5 feet in 

 that month alone. Chicago with 42 inches 

 and Milwaukee with 53, saw the worst snow 

 conditions in their histories. Farther south, 

 in a belt from the Ozarks to the upper Ohio 

 Eiver, equally large amounts of snow were 

 precipitated in January by the cyclones pass- 

 ing on the south, around the edge of the cold 

 snow blanket. October and December were 

 snowier than usual, especially December, in 

 much of the eastern half of the country. 



The weather was extraordinary not alone in 

 the eastern United States : west of the Eockies 

 the winter was one of the warmest on record. 

 Extreme dryness prevailed in the southwest; 

 but extraordinary rainfall occurred in the 

 northwest. In December a temperature of 

 86° below zero (F.) was rajwrted from the 

 Upper Yukon, at the mouth of the Pelly 

 Eiver. If authentic, this established a record 

 for ISTorth America which is only 4° (F.) be- 

 low the earth's extreme surface minimum 

 — 68° C. ( — 90.4° F.), observed in Siberia in 

 1892.= ISTorthern Sweden at about the same 



2 See Mo. Weather Eev., Feb., 1918. 



3 See note, ' ' The Lowest Air Temperature at a 

 Meteorological Station," Mo. Weather Bev., Vol. 

 45, 1917, pp. 407-408. 



time had unprecedented coldness — 57° C. ( — 

 70.6° F.) at Asele, and reports from Spain, 

 central plateau of France and southwestern 

 Asia teU of a winter of extreme severity. 



Why is the world having such unusual 

 weather? This is a period of sun-spot maxi- 

 mum — a time when solar radiation comes to 

 its maximum; a condition occurring on the 

 average once in 11 years.'' Experience has 

 shown that at such times there is a general 

 tendency in winter to strong continental 

 anticyclones and ocean cyclones; with corre- 

 sponding storminess and coolness." For North 

 America, a strong winter anticyclone generally 

 seems to favor coldness in the east and warmth 

 in the west.° Locally, the snowiest and cold- 

 est weather occurs where, in spite of low tem- 

 peratures, the supply of moisture is abundant 

 and the temperature contrasts produce the 

 storminess requisite to precipitate it as snow. 

 Then this snow keeps the air cold and helps 

 to make more snow; until important changes 

 in general winds dominate the weather and 

 eliminate the snow-cover — as was the case 

 early in February, 1918. While the present 

 degree of solar activity lasts, further occur- 

 rences of extreme weather are not unlikely. 



METEOROLOGY IN THE ABMY AND NAVY 



Since weather has much to do with military 

 operations, especially flying,' it was natural 

 that before one month had passed after the 

 entry of the United States into the war, in- 

 structors had been sent to the flying school at 

 Toronto for preparation to teach meteorology 

 at the six new aviation ground schools in the 

 United States. This work has progressed 

 quietly ever since. Professor E. DeC. Ward, 



■> For a further discussion, see C. G. Abbot, 

 "The Sun and the Weather," The Scientific 

 Monthly, Vol. 5, Nov., 1917, pp. 400-410. 



5 Cf. H. Aratowski, Bull. Am. Geog. Soc, 1916, 

 Vol. 42, pp. 270-282. 



See T. A. Blair, ' ' Some Temperature Correla- 

 tions in the United States," Mo. Weather Review, 

 Vol. 45, 1917, pp. 444-450. 



7 Cf. R. DeC. Ward 's most recent articles, Scien- 

 tific Monthly, February and April, 1918; and in 

 Jour, of Geography. 



