XV. 



ox THE THERMO-DYXAMICS OF THE ATMOSPHERE. 



(FmST COATMUXICATIOX.} 



Bv Prof. ^VlLHELM V(.)X Bf.zold. 



lu the application of tbe mecbauical theory of heat to the processes 

 goiug on in the atmospliere we have hitherto almost exclusively con- 

 fined ourselves to those cases in which one can disregard the increase 

 or loss of heat during the expansion or compression. 



The so-called convective equilibrium of the atmosphere, the unstable 

 equilibrium in cyclones, the phenomena of the fochn winds have all 

 hitherto been treated of under tl^ assumption that we have to do with 

 adiabatic changes of condition. 



In fact, especially in the last-mentioned phenomena, the quantity of 

 heat used or produced bj" expansion and compression as also by the 

 changes in the physical condition of the water, are so prominent in com- 

 parison with those that, in these rapidly executed processes, are intro- 

 duced or taken away by other sources that the above-mentioned as- 

 sumption may be said to be thoroughly allowable. In the investigation 

 of the convective equilibrium we obtain, under this assumption, at least 

 a glimpse of the special case that lies as a limiting case between the two 

 greater groups that correspond to the loss or increase of heat. Not- 

 withstanding these extremely restrictive assumptions, still through the 

 above-mentioned investigations, the comprehension of meteorological 

 processes has been furthered to such an extent that we must consider 

 their introduction as one of the characteristic features of modern me- 

 teorology. But the more valuable are the results that are already at- 

 tained in this manner, so much the stronger must be the desire to free 

 ourselves from the above-given limitations, and to extend the applica- 

 tion of the mechanical theory of heat to those atmospheric processes in 

 which the increase and diminution of heat from without can be no longer 

 neglected. That this generalization had not already been long before 

 taken is certainly because the formulte are extremely complicated, so 



* Translated Ircnu the Sitznn;jsberiekte der Konig. Preuss. Akademie der Wissenscha/ien 

 zu Btrlin: Berliu, April 26, l!?8e. pp. 485-522. 

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