XXII. On the Decrement of Atmospheric Temperature depending on the 

 Height above the Earth's Surface. By the Rev. J. Challis, 

 Plumian Professor of Astronomy and Experimental Philosophy 

 in the University of Cambridge. 



[Read February 13, 1837.] 



The temperature at any height above a given place on the Earth's 

 surface is here considered to be the mean which would be found by 

 a great number of thermometrical observations, made at that elevation, 

 for a time sufficiently long to eliminate the diurnal and annual va- 

 riations and the more irregular changes from winds. This mean tem- 

 perature, it is known, varies with the height, and the object of this 

 Paper is to enquire respecting the law of the variation. 



The causes which determine the temperature of the atmosphere at 

 a given elevation, are probably of a very complicated nature, but among 

 the principal may be reckoned the diminution of density in the higher 

 regions. In the following reasoning it is assumed, that the tempera- 

 ture and density are functions of the height, and the effect of decrease 

 of density will be considered apart from every other circumstance. If 

 then e be the temperature and p the density at the lieight x, we shall 

 have 



(d9\(j9 de dp 



\dx) dz^dp'dz' ^ ^• 



ip 

 Vol. VI. Paet III. sL 



