While most experiments on water or ice utilize rather complex, elaborate, and expensive apparatus in order to obtain reliable optical data, here we present a simple and affordable setup that enables us to perform near-infrared measurements on water, ice, and snow on top of rough diffuse reflecting surfaces such as concrete, stone, pavement, or asphalt. By using the properties of diffuse scattering instead of specular reflection, we are able to determine the imaginary part of the refraction index of water without using any liquid cells. In addition, we demonstrate that the snow spectra can be well described by newly developed two-dimensional ray tracing simulations.
The comparison between the albedo and reflectance factor is valid since for the used measurement geometry, the angle-dependent BRF in Fig. 11 shows a Lambertian behavior.
The average is needed since in two dimensions the angle-dependent results depend still too much on the orientation of the hexagonal shaped particles.