98 HOBBS— CHARACTERISTICS OF THE [April 22, 



Peary, while on the inland-ice in north Greenland in the month 

 of March, 1894, registered on his thermograph a temperature of 

 — 66° F. and several of his dogs were frozen as they slept."" The 

 high altitudes and the general absence of thick clouds over the 

 inland-ice, permit rapid radiation, so that cold snow wastes and hot 

 sand deserts have in common the property of wide diurnal ranges 

 of temperature. The poverty of the air over the inland-ice in its 

 content of carbon dioxide, as shown by the analysis of samples col- 

 lected by Nansen, must greatly facilitate this daily temperature 

 change."^ 



From studies in the Antarctic it is now known that most of the 

 snow falls there in the summer season, and that little, if any, mois- 

 ture can reach the interior from surface winds. The same is prob- 

 ably true also of the interior of Greenland. 



Though the absolute humidity of the air upon the ice plateau 

 of Greenland is always low, the relative humidity is large, and 

 never below 'j'}^ per cent, of saturation in the levels above 1,000 

 meters. Evaporation occurs chiefly when the sun is relatively 

 high, and when the air is again chilled the abstracted moisture 

 is returned to the surface in the form of the almost daily snow 

 mists or frost snow. The observations went to show that only in 

 the warmest days of summer do the sun's rays succeed in melting 

 a very thin surface layer of the snow. Of the thirty days that 

 Nansen's party was at altitudes in excess of 1,000 meters, on only 

 six is a definite snowfall reported. Within the interior of Green- 

 land it appears that no snozc zvhatever is pcrmancnily lost from the 

 surface by melting.'^- 



While the relative humidity of the air over the central plateau 

 is so high, the absolute humidity is extremely low, being measured 

 from 1.4 mm. to 4 mm., though generally much below the maximum 

 value. The average absolute humidity was 2.5 mm. while the 

 average relative humidity was 92 per cent.*'^ 



It has been claimed by v. Drygalski that the eastern portion of 



^ Geogr. Jour., Vol. 11, 1898, p. 228. 



®^ Mohn u. Nansen, /. c, pp. 109-111. 



*' Nansen, /. c, Vol. 2, p. 491. See also Peary, Geogr. Journ., I. c, p. 214. 



^ Mohn u. Nansen, /. c, pp. 44-45. 



