68 A WORLD ATLAS OF ATMOSPHERIC RADIO REFRACTIVITY 



180 150 120 90 



30 60 90 120 



180 150 



Figure C-9. Gradient (N/fara) exceeded 10 percent of the time for 100-m layer: August. 



Figure C-10. Gradient (N/km) exceeded 2 percent of the time for 100-m layer: August. 



