LONG-WAVE RADIO TELEPHONE TRANSMISSION 



691 



magnetic disturbance is obtained from similar analyses. Lowered 

 night-time fields on East- West (GBT, GBY) transmission were found 

 to accompany magnetic disturbances in both quiet and disturbed years. 

 However, from Fig. 8, it is seen that on West-East (WNL) trans- 





5 < 



si 



-5 



5 10 15 20 25 30 



RADIO FIELD STRENGTH IN DECIBELS ABOVE ONE MICROVOLT PER METER 



Fig. 8 — Cumulative distribution of daily averages of long- wave radio field strength 

 on days of magnetic calm and on days of magnetic disturbance. Night-time trans- 

 mission path, WNL. 



mission, the same result appears only in 1933, whereas in 1930 and 

 1932 night-time fields averaged higher on disturbed days than on calm 

 days. No reason for this inconsistency has been found. 



Correlation with Weather 

 Other investigators have shown some relation between long-wave 

 field strength and temperature ^^ and barometric pressure at short 

 distances.^'' Because of the greater range of weather conditions, the 

 relation is expected to be more obscure on long distance transmission. 

 However, on European signals (15 to 20 kc.) received at Washington 



