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The airborne spectral observations of the upward and downward irradiances arerevisited to investigate the dependence of the near-ground albedo as afunction of wavelength in the entire solar spectrum for different surfaces(sand, water, snow) and under different conditions (clear or cloudy sky). Theradiative upward and downward fluxes were determined by a diffractionspectrometer flown on a research aircraft that was performing multiple flightpaths near the ground. The results obtained show that the near-ground albedodoes not generally increase with increasing wavelengths for all kinds ofsurfaces as is widely believed today. Particularly, in the case of watersurfaces it was found that the albedo in the ultraviolet region is more orless independent of the wavelength on a long-term basis. Interestingly, inthe visible and near-infrared spectra the water albedo obeys an almostconstant power-law relationship with wavelength. In the case of sand surfacesit was found that the sand albedo is a quadratic function of wavelength,which becomes more accurate if the ultraviolet wavelengths are neglected.Finally, it was found that the spectral dependence of snow albedo behavessimilarly to that of water, i.e. both decrease from the ultraviolet to thenear-infrared wavelengths by 20–50%, despite the fact that their valuesdiffer by one order of magnitude (water albedo being lower). In addition, thesnow albedo vs. ultraviolet wavelength is almost constant, while in thevisible near-infrared spectrum the best simulation is achieved by asecond-order polynomial, as in the case of sand, but with opposite slopes

New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations