XIII. 



ON THE PHENOMENA OF MOTION IN THE ATMOSPHERE.* 

 (SECOND COMMUNICATION.) 



By Prof. A. Oberbeck, of Greifswald. 



I. 



A comparison of the highest and lowest atmospheric temperatures at 

 the surface of the earth shows permanent differences of 70°C. If the 

 pressure were uniform everywhere these would correspond to differences 

 of density of the air of more than 20 percent. Since, however, pressure 

 and density mutually influence each other one should therefore expect 

 minima of pressure at places of highest temperature and maxima of 

 pressure at places of low temperature of a corresponding intensity. 



Instead of this the average differences of pressure on the earth's sur- 

 face attain only G or 7 per cent., and even the largest rapidly passing 

 barometric variations scarcely exceed 10 per cent. We explain the 

 relatively small value of these differences of pressure by the formation 

 of corresponding currents ; a lower current at the earth's surface in the 

 direction of the increasing temperature and an opposite upper current. 

 Still the above-mentioned rule as to the connection between temperature 

 and pressure must be true in general. But this is by no means always 

 the case. While the equatorial zone of highest temperature shows a 

 feeble minimum of pressure there occurs a maximum of pressure be- 

 tween the twentieth and fortieth degree of latitude from which toward 

 either pole, and especially markedly in the southern hemisphere, the 

 atmospheric pressure very decidedly sinks. 



It appears to me not to be doubted that we can explain this re- 

 markable phenomenon only by the influence of the rotation of the earth 

 upon the currents of air that originate in temperature differences. In 

 a previous memoir! I have endeavored to carry out an analytical treat- 

 ment of these phenomena of motion under certain assumptions which. 



* Read before the Royal Prussian Academy of Sciences at Berlin, November 8, 1888. 

 Translated from the Sitzimgsherichte Konigl. rreus. Akad. der Wissenschaften zu Berlin. 

 1888, pp. 1129-1138. 



t [See the previous number (XII) of this collection of Translations.— C. A.] 

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