From the edge of the fetch to the transition zone 
At the edge of a storm at sea, in connection with the fore- 
casting problem, it is more convenient to line up the 9® equal to 
zero axis with the direction of the winds in the storm. The distance 
R, from the center of the forward edge of the storm to the edge of 
the transition zone is essentially the same, as far as the magni- 
tude of the parameters is concerned, as the distance to the point, 
ae Vp O in the transition zone. Thus in figure 32, the distance 
from A to B is essentially the same as the distance from A to Cc. In 
the process of forecasting considerations for the point, C, then, 
the procedures presented in Chapter 9 can be applied to reach the 
point, B, and then refraction theory can be applied without considera- 
tion of the added distance from B to C in order to find the effects 
at C. This procedure also neglects some minor effects on the power 
Spectrum since it varies slowly from point to point in deep water 
and all rays arriving at C do not come from B. Various operations 
must be applied to the power spectrum at the source in order to 
find the power spectrum at B and in order to put it into a mathe- 
matical form which permits the application of refraction theory to 
the power spectrum at B. Then the problem of prime importance in 
this chapter is to show how it is possible to go from the point B 
to the point C. 
The operations needed to proceed from point A to B and to orient 
the forecasted spectrum at B so that it can be easily refracted are 
Shown on the right of figure 32. The various terms are defined in 
Plate LXIV. 
At the forward edge of the storm, the power spectrum can be 
a2 
