In equation (9.68), figure 16 can be employed to find the 
# band width and the # cutoff values for a storm with a duration 
of ten hours and with any length fetch. The # band width depends 
upon Ds; R, F, and tobe 
Beebe cas vadtaenals 
Figure 24 and figure 25 are all the equipment needed to deter- 
mine the filter characteristics for the filter given by equation 
(9.68). Figure 25 is simply a graph of the straight lines given 
by top = 2p R/g (see Chapter 7, page 162) ona top» # coordinate 
system for various values of the parameter, R. Given De Fy top? 
and R, the appropriate graph of the straight line oa - D, = 
2H (R + F)/g can also be found, and the intersection of various 
lines on the diagram then determines  ,, and w , for the filter. 
The entire procedure for the evaluation of equation (9.68) 
for a fixed set of parameters with the use of figures 24 and 25 
will now be described. The given parameters, which could theo- 
retically be evaluated from weather maps are: storm width, 200 km 
(W.)3 fetch, 200 km (F); duration of storm, 15 hours (D,); x, 600 
km; y, 600 km; and time of observation, 40 hours (top 
The evaluation of the @-band width proceeds as follows. 
Tan ©» = y/x = 1, and Op = 45°. x = y = 3W,, and from figure 24, 
Ae, = 4.4° and A®, = 5.2°. The ©-band width is therefore 9.6° 
and the © cutoff points are at 49.4° and 39.8°. (From equations 
(9.65) and (9.66), Ae, = tan7+(1/13) and Ae, = tan7/(1/11). 
The evaluation of the # band width proceeds as follows. 
R equals “2 600 which equals 848 km. In figure 25, locate the 
line t., = 40 hours, and the line labeled 848(= 850) km. The 
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