346 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



of the lower stratum and the great and steadily-growing cyclone of 

 the upper stratum which are to be expected at the pole, break up 

 into a great number of irregular wandering cyclones and anti- 

 cyclones with a prevalence of the former." 



Thus at least the way is indicated by which we have to seek the 

 connection between the general circulation and the individual 

 phenomena such as cyclones and anticyclones which had hitherto 

 been considered as quite independent existences. 



We need only recall the investigations of Moeller, Oberbeck 

 and others, which also relate to the general circulation of the atmos- 

 phere. 



While theoretical researches thus pressed forward toward a 

 more general comprehensive treatment of all movements of the 

 atmosphere, Hann undertook 4 to give a basis of fact, deduced from, 

 the observations made at elevated stations, to the doubts that he 

 had previously expressed as to the incompleteness of the current 

 views. 



He demonstrated that in very various cases the temperatures in 

 the interior of cyclones and anticyclones up to considerable alti- 

 tudes are such that it is impossible to explain the existence of these 

 as due to the specific weight of the central column of air, and that 

 one is inevitably led to explain them as the result of the influence 

 of the general circulation. 



Therefore the theories hitherto accepted as to the origin and move- 

 ment of cyclones and anticyclones undoubtedly need important 

 modifications and it will be important to explain how the above- 

 mentioned local causes, or the specific gravity of the column of air 

 due to them, cooperates with the general circulation to bring about 

 the phenomena actually observed. 



It is comparatively easy to recognize this cooperation in the 

 arrangement of the mean annual and monthly isotherms of the 

 globe as I will briefly sketch it in the following paragraph. 



The difference of temperature between the equatorial and the 

 polar regions causes a flow of air in the upper regions of the equa- 

 torial zone towards the pole. This upper current will by reason of 

 the deflecting force of the diurnal rotation of the earth be converted 

 first into one from the southwest in the northern hemisphere but 



* Hann: On the relations between the variations of atmospheric pressure 

 and temperature on the summits of mountains. Met., Zeit. 1888, V, pp. 

 7-17. The Maximum pressure of November, 1889. Denkschriften d. 

 Vienna Akad., LVII, pp. 401—424, 1890. Remarks on the temperature in 

 cyclones and anticyclones. Met. Zeit., 1890, VII, pp. 328-344. 



