Predictions concerning the scattering and absorption characteristics of electromagnetic radiation interacting with nonspherical particles are obtained by suppression of particle resonances (surface waves) in classical Mie scattering theory. The importance of the particle resonance phenomenon and thus the nonspherical corrections is related to the three classical variables ni, nr, and x, the imaginary and real components of the index of refraction and the size parameter, respectively. The resonance phenomenon becomes increasingly restricted to small values of x as nr increases. For solar wavelengths and cloud size particles resonance phenomenon may be neglected for nr ≳ 2. As nr decreases the effect of nonsphericity becomes increasingly significant to both scattering and absorption. For nr ≲ 2.0 and ni ≃ 10−5, suppression of particle resonances in Mie theory predicts increases in absorption efficiency of several orders of magnitude in the region of the absorption peak.
© 1978 Optical Society of America
Original Manuscript: January 14, 1978
Published: October 1, 1978
R. M. Welch and S. K. Cox, "Nonspherical extinction and absorption efficiencies," Appl. Opt. 17, 3159-3168 (1978)