506 



BELL SYSTEM TECHNICAL JOURNAL 



sweep patterns were photographed at or shortly after the time of 

 flight. These sweep patterns were all on horizontal polarization. 



From the meteorograph data, kindly furnished us by the United 

 States Weather Bureau, the dielectric constant of the air has been 

 calculated ^ and plotted as a function of the altitude. On twenty-four 

 days there were, above an altitude of 400 meters, changes in the 

 dielectric constant curves equivalent to discontinuities of Ae ^ 10~^. 

 Heights up to 3200 meters were recorded for these. Typical curves 



JUNE: 27,1936 

 2 COMPONENT 



JUNE 28,1936 

 3 COMPONENT 



6-03:53 



MAY 19,1936 

 MULTI-COMPONENT 



8-2105 



*v 65052' 



64 66 69 64 66 69 



FREQUENCY IN MEGACYCLES 



64 66 69 



Fig. 13 — Three sequences of frequency sweep patterns. Horizontally polarized 

 transmission, 4.55 meters mean wave-length. 



are given in Fig. 18 on the left-hand side. On four days there were 

 small boundaries with Ae < 10~^; on two days there were possible but 

 not definite boundaries, the experimental points being too widely 

 separated in altitude for precision; on five days there were possible 

 boundaries below 400 meters altitude and on ten days the refractive 



