SystemNormXsecBscatterSphere
returns the normalized Backscatter cross-sectional
area of a sphere using the Rayleigh approximation
From Rinehart (1997), Eqn 4.9 and 5.7 and Battan Ch. 4.5
SystemNormXsecBscatterSphere(D, lam, K=0.93)
R. E. Rinehart, 1997 Radar for Meteorologists Rinehart Publishing
L. J. Battan, 1973 Radar observation of the atmosphere The University of Chicago Press