The Surface Reflection of a Mat Surface

[摘要] The total reflection of a mat surface such as of snow, white wall and soil, consists of two parts. The one is the reflection from the surface and the other the reflection due to the multiple reflection inside the medium. This paper treats the problem of the reflection merely from the surface itself.We denote the angle between the normal of any facet, which is a component of the_??_mat surface, and the normal of the mean surface, by θ. As the distribution function W(θ) of the directions of the facets, we take the form, following the line of the discussion by L. S. Ornstein.(2) However, contrary to Ornstein, who assumed that every facet reflects the light totally like a mirror, the present author hag assumed that reflectivity, _??_, obeys Fresnel's formula.After some calculation, we have obtained that R_??_. the partalbedo due merely to the surface itself, is given by when the incident light is of parallel nature and has the incident angle In the above equation, _??_, i and θ are given by the equations (1), (6) and (7) in the original Japanese paper by the author, respectively.When the incident light is of diffused nature, we make use of the relation between M_??_ and M_??_, where means the intensity of reflection of _??_ -direction when the incident light is diffuse, and M_??_means the total amount of reflection when the incident light is of parallel nature and of the incident angle _??_ . This equation was formerly obtained by M. A. Boutaric, (4) and has been re-obta-ined in much simpler way by this author in the present article.Making use of Boutaric's relation, it has been proved that, for the incident light of diffused nature, the albedo of the reflection due merely to the surface itself, is given by the equation.

[学科分类] 大气科学