176 



SYNOPTIC RADIO METEOROLOGY 



400 



300 



N 200 



100 - 





 2 4 6 8 10 12 14 



h(knn) 



Figure 5.1. Mean N distribution for Isachson, N.W.T., Canada. 



less than a month during the summer of 1947. Within the framework of 

 this speciahzed study, however, Randall found that polar continental air 

 masses were associated with low field strengths and low A^^ while tropical 

 maritime air masses were associated with high field strengths and high 

 N s, as shown on figure 5.3. Randall advanced the hypothesis that the 

 observed field strength changes were due to the existence of characteristic 

 A^ profiles typical of each air mass type. Randall was curious also as to 

 the behavior of A'' and radio fields during the passage of fronts and squall 

 lines. Figure 5.4 shows the results of this investigation and indicates that 



