Colors of glacier water


  • Eyvind Aas,

  • Jim Bogen


The optical characteristics of sediment suspensions in the glacierfed lake Veitastrondsvatn are examined to explain observed color variations. The color depends on the wavelength where the ratio between the backward scattering coefficient and the absorption coefficient of the suspension has its maximum, and this usually coincides with the wavelength where the absorption has its minimum. It is found that the absorption coefficient of the small particles of clay and silt size decreases with increasing wavelength, but that the absorption coefficient of the suspension obtains a minimum in the green part of the spectrum, due to the strong absorption of red light by water. The suspension of such particles in the surface layer of the lake will then appear green. The coefficients of larger particles of sand size are almost independent of wavelength, with no significant maximum or minimum, and river waters close to the glacier fronts, which are dominated by these particles, will appear milky.