30 



BLAIR— EXPLORATION OF THE UPPER AIR [March 5, 



ties in the temperature gradient as recorded from day to day in the 

 lower stratum, since these, together with the wind directions and 

 velocities, must be relied upon for a knowledge of the air circula- 



N 

 km. 



15 



14 



13 



12 



10 



W 



Start 1 

 S 



3 4 5 6 7 8 9 10 11 12 13 14. km 



*j(. 



Fig. 10. Horizontal projection of path of a sounding balloon, Uccle, 

 Belgium, July 25, 1907. 



tion in particular storms as they pass. Among the most interesting 

 of these peculiarities are the inversions. Fig. 9 shows a charac- 

 teristic series beginning on September 15, 1908, and ending Septem- 

 ber 19, 1908. The advent of this inversion is preceded by a small 

 temperature change with altitude at 2,900 meters on September 14. 



