84 A WORLD ATLAS OF ATMOSPHERIC RADIO REFRACTIVITY 



180 150 



90 60 



30 



30 60 90 120 150 180 



Figure C-41. Lapse rate of refractivity (N/km) exceeded 25 percent of time for 100-m layer: February. 



180 150 



FIGURE C-42. Lapse rate of refractivity (N 'km) exceeded 10 percent of time for 100-m layer: February. 



