82 A WORLD ATLAS OF ATMOSPHERIC RADIO REFRACTIVITY 



70 

 180 150 120 





-30 



-15 



^0 



-15 



-30 



-60 



60 30 



— 170 

 30 60 90 120 150 180 



Figure C-37. Percent of time trapping frequency < 300 Mc/s: August. 



Figure C-38. Percent of time trapping frequency < 3000 Mc/s: November. 



