DYNAMIC METEOROLOGY. 



389 



Fig. 1.— Wiud currents. 



for instance, its transfer into the northern hemisphere), would cause a 

 corresponding change of all the currents. 



" The accompanying sketch, Fig. 1, gives a picture of the atmospheric 

 cui rents as they would result from the adopted distribution of tempera- 

 ture. This presents the eai'th's surface iu the Mercator projection. 

 The curves u and w represent the currents of air in the lower strata; 

 the curves o and o .in the upper strata of the atmosphere. At the 

 equator and at the poles the vertical 

 currents serve as the means of transi- 

 tion of the lower currents into the 

 upper, and vice versa. The lower 

 current can, under favorable circum- 

 stances, come to be observed at the 



earth's surface. In fact, the diagram 

 presents iu its u curves in the tro[)ics 

 the trade winds as they prevail over 

 the Pacific and Atlantic Oceans, and 

 also the west wind as it prevails be- 

 yond the fortieth degree of latitude. 

 From theagreementof the wind paths 

 iu this diagram with those actually 



observed, the important conclusion can be drawn that iu general the 

 currents u and Oi are of the same order of magnitude. Hence, it fol- 

 lows that 02or the upper easterly current must be of materially greater 

 intensity than the lower currents. The ui)i)er wind paths agree iu the 

 tropics with the anti-trade. In higher latitudes the west wind must 

 principally prevail in the upper regions. 



"In the very highest strata of air the currents must again diminish 

 iu strength; this is to be concluded from the fact that the two quanti- 

 ties C and D contain the density of the air as a factor which enters in 

 its first power into C, but in its second power into D. • 



"To this general presentation of the currents of air the detailed com- 

 putation of the distribution of pressure is still lacking b\' this execu- 

 tion, ])erhaps some unimportant modifications of the results here com- 

 municated may be attained." 



(22) Oherheclc. — In his third communication on this subject (the second 

 of 1888), Oberbeck passes from a consideration of the motions of the at- 

 mosphere to that of the general distribution of i)ressure that results 

 from the movements, which themselves result from the distribution of 

 temperature, or more properly of density. In this case he again deals 

 with the hypothetical atmosphere of uniform density and depth adher- 

 ing to the earth but gliding under the upper layers and adopts the ap- 

 proximate law of temperature of the air as above given. His general 

 solution of the equations leads to the formula : 



jp=constaut-+-w co^^d—n cos^O. 



In the southern hemisphere we have conditions that approximate 

 those here adopted more nearly than in the northern, and having shown 



