MOUNTAIN CLIMATE 



691 



Each reduction in the atmospheric pressure is accompanied by a corre- 

 sponding reduction in the temperature of the air, because with increasing- 

 rarefaction the absorption of the sun's rays is reduced. The cooling due to 

 increasing altitude averages 0-58° C. for 100 meters, somewhat more therefore 

 than has been assumed in the preceding table ; it is, however, to a certain 

 extent dependent on local influences. The following tables compiled by 

 Hann give the average reduction in temperature according to altitude, 

 based upon direct observations in various mountainous countries : — 



VARIATION IN TEMPERATURE PER 100 METERS IN CENTIGRADE 



DEGREES. 



(After Hann, Bd. I, p. 270.) 

 I. Tropical Mountains. 

 Andes of Columbia and Mexico (Humboldt) 

 Andes of S. America between ii° N. and 5 S. (Boussingault) 

 N. W. Himalayas (Blanford) 

 N. W. Himalayas with Tibet (Hill) 

 Central Himalayas (Blanford) 

 Nilgiris (Hann) .... 



Ceylon (Hann) .... 



Java (Batavia-Pangerango) . 



II. Temperate Mountains. 

 Siebengebirge (Bischof) 

 Erzgebirge (Reich) .... 

 Erzgebirge (Hann) .... 

 Harz (Hann) ..... 

 Alps (Hann, Hirsch, Wielenmann) 

 Blue Mountains of the north of New South Wales (Hann) 

 Caucasus and Armenia (Wild) 

 Mount Washington, New Hampshire (Hann) 

 Pike's Peak, Colorado (Hann) 

 California (Colfax, summit 1 

 At Christiania (Mohn) 



Y y 2 



c-53 



0-57° 



0-56° 



0-51° 



0-52° 



0-62° 



0-65° 



0-56° 



0-56° 

 0-52° 

 0-59° 

 0-58° 

 0-58° 

 0-51° 

 0-45° 



c-55° 

 0-63° 

 0-75° 

 c-55° 



