142 



and 



N CLIMATOLOGY 



c = 2.514 X 102. 



The maximum wavelengths trapped during ducting conditions were 

 estimated by (4.24) for the maximum duct thicknesses of figure 4.40. 

 These values, given in table 4.7, were determined for the month with the 

 maximum occurrence of ducts, thus allowing an estimate of the radio 

 frequencies likely to be affected by ducting conditions. Note, for ex- 

 ample, that the data of table 4.8 indicate that 1000 Mc/s rays (X = 30 cm) 

 will be trapped by 50 percent of the ducts regardless of location. 



FEB. MAY AUG NOV 



FEB MAY AUG NOV 



FEB MAY AUG NOV 



Months of the Year 

 Figure 4.37. Angle of penetration of ground-based ducts. 



