SCIENTIFIC BALLOON ASCENSIONS VON BEZOLD 30 I 



above computed. In fact in these strata the average curve of con- 

 dition rises much more steeply than should be the case under the 

 assumption above made. 



This is remarkable inasmuch as thus the problem is to a certain 

 extent reversed as compared with the older views. 



Hitherto it has been believed that we could only explain the higher 

 temperature of the lower strata by the suspicious hypothesis of 

 the non-transmissibility of dark rays through the atmosphere, 

 but now we must seek the reasons why the diminution of tempera- 

 ture with altitude is not far greater than observation shows it to 

 be, at least in the lower and middle strata. 



For the condensation, which contributes in an important degree 

 to diminish this gradient, still does not suffice to fully explain the 

 observed diminution. 



The ideal curve sketched in fig. 40 departs from observation even 

 still further, in its lowest portion. Whereas according to the general 

 scheme one should expect larger gradients in the lowest stratum 

 than in the median strata, yet in fact according to the numbers 

 deduced from the balloon voyages for the lowest three kilometers 

 there is a nearly constant and rather small value for the gradient. 



It was to be expected that our scheme would fail in this portion, 

 since near the earth's surface, where radiation and absorption come 

 into play to such a large extent, it is only seldom that pure adiabatic 

 processes can occur. 



Especially at times of excessive outward radiation must the ideal 

 scheme be disturbed, since at such times the lowest strata become 

 relatively cold, whereas the opposite is the case at times of excessive 

 inward radiation (or insolation) and thereby an approximation to 

 unstable equilibrium or even that condition itself may easily occur. 



Actually, however, it is only the general average whose course 

 departs so far from the ideal, on the other hand, the average 

 values for the summer, which will be considered in the third section 

 of this memoir, do, especially in the lowest portion, approximate far 

 more closely to the ideal. 



To a much higher degree do various individual cuves resemble the 

 form of the theoretical scheme. In this respect I recall the curves of 

 condition given in volume 2 (of the Ergebnisse) for the voyages, 

 No. 1, p. 10; No. 4, p. 38; No. 10, p. 106; No. 11, p. 121; No. 60, 

 p. 553; No. 67-70, p. 579, and No. 72, p. 601. 



Hence the course of the lowest portion of the temperature curve 

 can be very well explained by the overpowering influence of the 

 radiation, as will be hereafter more precisely set forth. On the 



