1322 



degree of certainty ; it may be considered reraaikable tliat also in 

 these levels the direction spirally turns from ESE through E to 

 ENE, when we proceed upwards. 



The usual explanation of trade and antitrade still remains accept- 

 able viz. in the southern hemisj>here the air which flows towards 

 the equator gives birth to an ESE-current owing to the rotation. 

 This air ascends and has to tlow off. By rotational influence it 

 deviates more and more to the left, turning from ESE through E 

 towards ENE. In latitudes higher than that of Batavia its direction 

 eventually becomes N and NW. 



It should be observed, that a slight rising of the air suffices to 

 cause a rapid deflux, because the horizontal j)lane through which 

 rising takes place, exceeds so much in extension the vertical one 

 through which the air flows off. For instance rising over 10 degrees 

 of latitude (more than 1000 km.) and deflux through a layer 10 

 km. thick, give a ratio of a quick deflux with velocity of meters 

 against a slow i-ising by centimeters. 



The nature of the phenomenon of convection makes it easy to 

 understand the existence of a level with maximum deflux; its alti- 

 tude above Batavia is rather high viz. 14 km. in Aug. and 15 km. 

 in February. 



That the flow is less in the southern summer is evidently caused 

 by the fact that the thermic equator has a more southern [)Osition 

 in this season and accordingly that part of the zone of deflux, which 

 lies to the north of Batavia is smaller than the one in the other 

 season. In accordance with this also the deviation of the direction 

 to the left is slighter. 



Important information about this flow gives the drift of Ci-clouds, 

 because these clouds float in the layers of the antitrade; at Batavia 

 their average height is 13 km. in the southern summer and in 

 winter 11 km. 



The following mean directions of drift have been observed. 



Batavia 



Pontianak 



Manila 



In Dec/Febr. the thermic equator is situated near to the latitude 

 of Batavia; in accordance with it the deviation from E-drift is nearly 



