Scattering from nonspherical Chebyshev particles. 3: Variability in angular scattering patterns.

We study shape-induced variability in the scattered intensity from randomly oriented nonspherical particles. Up to 21 different Chebyshev shapes contribute to defining a shape-induced standard deviation about each of the mean nonspherical intensity vs angle curves shown in part 2 of this series. Bands of shape-induced variability (defined as plus and minus one standard deviation) for six size intervals within the size parameter range 1 </= x </= 20 are compared with corresponding spherical intensities. Averaging spherical intensities over narrow size ranges produces effects qualitatively similar to mildly distorting a single sphere. Nevertheless, among all shapes, the sphere is often the most anomalous scatterer; nonspherical scattered intensities tend to be closer to one another than to corresponding spherical intensities. For Chebyshev particles which are neither small nor large compared to the wavelength, shape-induced variability is often comparable to the mean. Furthermore, outside the forward-scattering reg ion, this variability is large relative to the deformation from a sphere. The standard deviation is up to 50% of the mean scattered intensity for particles with an average deformation of only ~10%. This exaggerated sensitivity to shape will make it difficult to define representative angular scattering curves for many real-world nonspherical scattering problems which involve imperfect shape information.