On the effects of size factor on albedo versus wavelength for light scattered by small particles under Mie and Rayleigh regimes

TL;DR

This paper investigates how particle size and optical properties influence the wavelength-dependent albedo of small particles, providing insights into spectral bluing phenomena observed on planetary surfaces.

Contribution

It introduces a mathematical analysis of the impact of grain size and optical index on albedo, advancing understanding of spectral bluing and reddening in planetary surface scattering.

Findings

Monomodal size distributions cause spectral bluing across the spectrum.

Spectral bluing occurs regardless of optical index under certain size conditions.

Conditions for spectral reddening are also identified.

Abstract

Scattering by particles significantly smaller than the wavelength is an important physical process in the rocky bodies in our solar system and beyond. A number of observations of spectral bluing (referred to in those papers as "Rayleigh scattering") on planetary surfaces have been recently reported, however, the necessary mathematical modeling of this phenomenon has not yet achieved maturity. This paper is a first step to this effect, by examining the effect of grain size and optical index on the albedo of small conservative and absorbing particles as a function of wavelength. The basic conditions necessary for spectral bluing or reddening to be observed in real-world situations are identified. We find that any sufficiently monomodal size distribution of scattering particles will cause spectral bluing in some part of the EM spectrum regardless of its optical index.