256 THE MECHANICS OF THE EARTH'S ATMOSPHERE. 



higher temperature inured to the places at or above which the con- 

 densation occurred. 



The mechanical theory of heat shows that the current ascending in 

 the calm zone must precipitate its water right there in the form of 

 tropical showers, and that then it must descend as a drier and also as 

 a warmer current (except in so far as it does not experience any mate- 

 rial cooling, especially at the earth's surface). This theory further 

 shows that the heat of condensation, in so far as super-saturation proper 

 does not come into consideration, never shows itself as actually warm- 

 ing but only as diminishing the cooling that accompanies the ascent of 

 the air, so that the current arrives at the upper limit warmer than it 

 would without the accompanying condensation, and that the heat thus 

 economized benefits the point at which the descending current reaches 

 the earth's surface. 



The considerations here developed can of course only be considered 

 as approximate steps that still await additions and corrections. To 

 my eye they play a role similar to that of the investigation of the so- 

 called solar climate in climatology. Moreover some of these have no 

 claim to complete novelty, but will be found here and there in connec- 

 tion with other special investigations. 



On the other hand, they have never as yet been developed in such 

 general — and never in such a simple — manner as is here done with the 

 help of the idea of " potential temperature " and of the theorems that it 

 was possible to deduce from this as to the potential temperature of the 

 different layers of air. The consequences that can be deduced from 

 this as to the static relations of the atmosphere, especially with refer- 

 ence to the fundamentally different behavior of cyclones and anti- 

 cyclones in winter and in summer, both in respect to their intensity 

 and their duration, are delayed to a later communication. 



[An Appendix as published in the original memoir by von Bezold 

 is omitted from this translation, as it has been at the author's request 

 incorporated in its proper place in the latter portion of his first com- 

 munication.] 



