Chap. I] 



MOUNTAIN CLIMATE 



6 93 



14° higher than the boiling-point of water, which at this altitude is only 



88° c: 



DIFFERENCE IN TEMPERATURE IN SUN AND SHADE ON MOUNTAINS 



AND IN LOWLANDS. 



(After Hann, Bd. I, p. 229.) 



Of the inequality in the cooling at night-time in lowlands and on moun- 

 tains respectively the following observations give instances : ' Comparative 

 measurements of the radiation at Brienz and on the summit of the Faulhorn 

 (2.110 m.) gave 37 °/ greater radiation of heat on the Faulhorn; similar 

 observations, conducted simultaneously at Chamonix and on the Grand 

 Plateau of Mont Blanc (3. 930 m.), gave nearly twice the radiation of heat 

 (at about 93 °/ o ) on the Grand Plateau, which stands 2,880 m. higher. The 

 temperature of the snow on the Grand Plateau sank on the nights from 

 the 28th to the 31st of August, 1844, to — 19-2°, whilst the temperature of the 

 air was still —6-j C * 



Regarding the lowering of the temperature at night-time on the summits 

 of Javanese volcanos, 9,000-12,000 feet high, Junghuhn 2 makes the following 

 statement, which my own experience also confirms : — 



' The sun has scarcely reached the horizon, when a quick and even sudden change 

 occurs. On the very summit all movement instantly ceases. The wind usually 

 stops entirely, not a trace of cloud passes, and the atmospheric temperature sinks 

 rapidly and so low that one makes no delay in donning an overcoat or wrap. The 

 Javanese keep squatting closer together round the blazing fire, for the thermometer, 

 that a short time before, whilst the sun went down, still stood at 8-4° R. (10-5° C), 

 has already sunk to 5-5° R. (f C), and indeed sometimes from 9-3° R. (n-6° C.) to 

 4-4 c R. (5-5° C). . . . Before midnight, the temperature often sinks even below 



1 Hann, op. cit., Bd. I, p. 235. 



Junghuhn, op. cit. 



