XXI 



ADIABATIC CHANGES OF CONDITION OF MOIST AIR 

 AND THEIR DETERMINATION BY NUMERICAL AND 

 GRAPHICAL METHODS 



BY DR. OTTO NEUHOFF 



I Memoirs of the Royal Prussian Meteorological Institution, Vol. I, No. 6. 

 Berlin, igoo, pp. 271-306] 



§ I. INTRODUCTION 



The investigation of the adiabatic changes in the condition of 

 moist air, that is to say, those changes that a mass of air experiences 

 when it is expanding as it rises, or when it is being compressed as it 

 sinks, without addition or diminution of its internal heat, has 

 achieved a very prominent importance in modern meteoroh gy. 

 The old view as to the formation of precipitation, in which Me 

 attributed the principal influence to the mixture of masses of air 

 having different temperatures, and also the idea that the heat of 

 condensation of water raises the temperature of the place above 

 which the condensation occurs, became untenable after the more 

 accurate study of the foehn winds in the Alps by von Helmholtz 

 (1862) and Hann (1866) had lei to very different results. It was by 

 the application of the principles of the mechanical theory of heat 

 to the processes in the atmosphere that we attained to the laws of 

 the changes of temperature in ascending or descending air, 'and 

 these latter were thus established by the most prominent philos- 

 ophers, such as Lord Kelvin, 1 Reye, 2 and Peslin. 3 



In the publications of Hann, 4 and Guldberg and Mohn, 5 the 



1 W. Thomson: On the convective equilibrium in the atmosphere. Mem. 

 Manch. Soc. (3) II, 125-131. 



2 Reye: Vertikale Luftstrome in der Atmosphare. Zeitschr. f. Math.. 

 1864, IX, S. 250-276. 



:i Peslin: Bull. hebd. de l'Assoc. scient. de France, 1868, III. 



4 Hann: Die Gesetze der Temperaturanderung in aufsteigenden Luft- 

 strOmungen und einige der wichtigsten Folgerungen aus denselben. Meteorol. 

 Zeitschr., 1874, S. 321—29, 337-46. 



b Guldberg and Mohn: Etudes sur les mouvements de l'atmosphere. 

 Christiania, 1876 and 1880. Ueber die Temperaturanderung in vertikaler 

 Richtung der Atmosphare. Meteorol. Zeitschr., 1878, S. 1 13-124. 



43° 



