def glint_spectra(self, geom, L_down_dir, L_down_dif):
        """Calculates the sun (dir) and sky (dif) glint spectrums"""
        rho_ls = self.fresnel_rf(geom.observer_zenith)
        # direct sky transmittance
        g_dir = rho_ls * (L_down_dir / (L_down_dir + L_down_dif))
        # diffuse sky transmittance
        g_dif = rho_ls * (L_down_dif / (L_down_dir + L_down_dif))

        return g_dir, g_dif

    def calc_rfl(self, x_surface, geom, L_down_dir=None, L_down_dif=None):
        """Direct and diffuse Reflectance (includes sun and sky glint)."""
        # fresnel reflectance factor (approx. 0.02 for nadir view)
        g_dir, g_dif = self.glint_spectra(geom, L_down_dir, L_down_dif)

        sun_glint = x_surface[-2] * g_dir
        sky_glint = x_surface[-1] * g_dif

        rho_dir_dir = self.calc_lamb(x_surface, geom) + sun_glint
        rho_dif_dir = self.calc_lamb(x_surface, geom) + sky_glint

        return rho_dir_dir, rho_dif_dir

    def calc_rfl(self, x_surface, geom):
        """Direct and diffuse Reflectance (includes sun and sky glint)."""
        # fresnel reflectance factor (approx. 0.02 for nadir view)
        rho_ls = self.fresnel_rf(geom.observer_zenith)

        sun_glint = x_surface[-2] * rho_ls
        sky_glint = x_surface[-1] * rho_ls

        rho_dir_dir = self.calc_lamb(x_surface, geom) + sun_glint
        rho_dif_dir = self.calc_lamb(x_surface, geom) + sky_glint

        return rho_dir_dir, rho_dif_dir