EXPONENTIAL MODEL 



67 



o 



Q 

 < 



500 



300 

 200 



100 

 70 

 50 



30 

 20 



10 

 7 

 5 



3 

 2 



0.7 

 0.5 



0.3 

 02 



0.1 



4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 

 ALTITUDE IN KILOMETERS ABOVE SEA LEVEL 



Figure 3.5. CRPL reference refractivity atmospheres — 1958. 



aid in distinguishing between the various models, the following sections 

 will be concerned with comparing the ray bending between the models. 

 A comparison of the ray paths in the reference atmospheres in the 4/3 

 earth model will illustrate the systematic differences between these 

 models. Such a comparison is given in figure 3.7 for a distance of 200 mi 

 and a height of 14,000 ft and in figure 3.8 for a distance of 800 mi and a 

 height of 240,000 ft. The particular graphical presentation used in 

 figures 3.7 and 3.8 shows the 4/3 earth rays as straight lines. It is noted 

 that the 4/3 earth ray at 0o = is in relatively good agreement with the 

 values from the reference atmosphere for distances out to 200 mi and 

 heights up to 14,000 ft, but systematically departs from tlu^ n^ference 



