Appendix F. TEMPERATURE AT DIFFERENT ELEVATIONS. 



405 



with a lower mean temperature, the equivalent difference is 27°. At 

 11,000 feet this difference is equal to that of London. In more 

 elevated regions, it is still greater, the climate becoming excessive 

 at 15,000 feet, where the difference amounts to 30° at least. # The 

 accompanying table is the result of an attempt to approximate 

 to the mean temperatures and ranges of the thermometer at various 

 elevations. 



Altitude. 



Mean 

 Shade. 



Mean 



Warmest 



Month. 



Mean 



Coldest 

 Month. 



Mean 

 Daily 

 Range of 

 Tempera- 

 ture. 



Rain-fall 

 in inches. 





] 1,000 feet... 

 15,000 feet... 

 19,000 feet... 



40-9 

 29-8 

 19-8 



500 

 40-0 

 32-0 



24-0 

 11-0 



o-o 



20-0 



27*0 

 35-0 



40-0 

 20-0 

 10-0 



1°=320 feet. 

 1°= 350 feet. 

 1°= 400 feet. 



Supposing the same formula to apply (which I exceedingly doubt) 

 to heights above 19,000 feet, 2° would be the mean animal tempera- 

 ture of the summit of Kinchinjunga, altitude 28,178 feet, the 

 loftiest known spot on the globe : this is a degree or two higher than 

 the temperature of the poles of greatest cold on the earth's surface, 

 and about the temperature of Spitzbergen and Melville island. 



The upper limit of phenogamic vegetation coincides with a mean 

 temperature of 30° on the south flank of Kinchinjunga, and of 22° 

 in Tibet ; in both cases annuals and perennial-rooted herbaceous 

 plants are to be found at elevations corresponding to these mean 

 temperatures, and often at higher elevations in sheltered localities. 

 I have assumed the decrease of temperature for a corresponding 



i This is contrary to the conclusions of all meteorologists who have studied 

 the climate of the Alps, and is entirely due to the local disturbances which I have 

 so often dwelt upon, and principally to the unequal distribution of moisture in the 

 loftier rearward regions, and the aridity of Tibet. Professor James Forbes states 

 (Ed. Phil. Trans., v. xiv. p. 489) : — 1. That the decrement of temperature with 

 altitude is most rapid in summer : this (as I shall hereafter show) is not the case 

 in the Himalaya, chiefly because the warm south moist wind then prevails. 

 2. That the annual range of temperature diminishes with the elevation : this, too, 

 is not the case in Sikkim, because of the barer surface and more cloudless skies 

 of the rearward loftier regions. 3. That the diurnal range of temperature 

 diminishes with the height : that this is not the case follows from the same 

 cause. 4. That radiation is least in winter : this is negatived by the influence of 

 the summer rains. 



