Radiative Properties of Non-black Surfaces

Abstract

This chapter presents an elaborate treatment of radiative properties of non-black surfaces. First, gray and diffuse surfaces are introduced, followed by a definition of spectral directional emissivity. Integrated quantities such as hemispherical spectral emissivity and directional total emissivity are mathematically defined, followed by a mathematical definition of hemispherical total emissivity. This approach is then extended to absorptivity, reflectivity and transmissivity. For a plane-parallel medium, the idea of a directional transmissivity vanishes. This chapter ends with a brief introduction to optical pyrometry. Fully worked examples are presented to reinforce the definitions of the key radiative properties.