80 A WORLD ATLAS OF ATMOSPHERIC RADIO REFRACTIVITY 



180 150 



30 30 60 90 120 150 



BO 

 — 1 80 



60 



70 



180 150 120 90 60 30 30 60 90 120 150 



J 70 



Figure C-33. Percent of time trapping frequency < 1000 Mc/s: May. 



180 150 120 90 60 30 



30 60 90 120 150 180 



70 1 



180 150 120 90 60 30 30 



170 



60 90 120 150 180 



Figure C-34. Percent of time trapping frequency < 300 Mc/s: May. 



