VERTICAL DISTRIBUTION OF THE REFRACTIVE INDEX 



211 



5.7. Vertical Distribution of the Refractive 

 Index Using A Units 



The synoptic study of the vertical distribution of the radio refractive 

 index extends the foregoing constant-level analyses by considering the 

 problem of whether the air mass properties associated with this typical 

 wintertime outbreak of polar air are reflected in the vertical refractive 

 index structure. Charts showing the structure of the storm have been 

 prepared using radiosonde measurements from stations located along a 

 line normal to the frontal zone between Glasgow, Mont., and Lake 

 Charles, La. (fig. 5.41). Plots of A'^ versus height along this cross section 

 line were obtained at 12-hour intervals during a 4-day period and con- 

 verted to A units. 



Figure 5.42 is an example cross section along the Glasgow-Lake Charles 

 line analyzed in terms of unmodified A'' as in the idealized cases of figures 

 5.11 and 5.12. Compare this figure with the A unit analysis of figure 

 5.48 for the highlighting of air mass differences refractive-index-wise. 

 Examples of the distribution of A'^ components, temperature and humidity, 

 around the front are charted on figures 5.43 and 5.44. Various stages 

 in the advance of this intense storm system across the continent are 

 represented by figures 5.45 to 5.50 in terms of modified A'^ (A units). At 

 the outset of the period of observation (fig. 5.45), the polar front was 

 located over the northern Great Plains, between Rapid City, S. Dak. 



Figure 5.41. Station identificalion chart. 



