The radiative transfer equation has been solved numerically for semi-infinite plane parallel cases using Chandrasekhar's H-functions, as well as by implementing a more general matrix formulation. The solutions have then been compared to a parametric model, derived by Rosendahl.The comparisons showed that the solution to the radiative transfer equation is non-linear in its behaviour with respect to the single scattering albedo and that a more general method for comparing the two models is needed. A more general method is therefore suggested and implemented as an inverse problem formulation. The results from the numerical simulations using the inverse problem formulation, showed that neither the use of the Henyey Greenstein phase function, nor a more general low order phase function exhibits similar behaviour as the parametric model. This thesis shows that it is possible to modify the parametric model to better suit radiative transfer approximations. Finally, frequency resolved measurements has been done on white, fine grained snow. The inverse problem formulation is then used to obtain the corresponding solution to the radiative transfer equation. The results from the measurements show that it is possible to model the reflection distribution from a snow surface using the Henyey Greenstein phase function. Better results can be obtained, however, by using a more general low order phase function. Comparisons with the modified parametric model showed that the modified model has difficulties in resolving the direct reflection that arise from the snow surface. When measurements were done on an ice covered snow surface, the results showed that more complex modelling is necessary.