Visible albedo

In contrast with the relatively straightforward interpretation of the water ice/frost absorptions in Ganymede and Callisto s spectra, identihcation of the non-ice material on these satellites has proved more difficult. Although small amounts of dark, opaque material mixed with bright ices are sufficient to drastically lower the visible albedo... 

Vilas, F., Jarvis, K. S. and Gaffey, M. J. (1994) Iron alteration minerals in the visible and near-infrared spectra of low-albedo asteroids. Icarus, 109, 274-283. 

Shoulders or peaks were observed at 465, 443 and 425 nm of the visible spectrum (due mainly to the carotenoids present) and 325, 280 and 245 nm of the ultraviolet spectrum (due mainly to polyphenols, flavonoids and ascorbic acid, respectively). Absorbance of the maxima peaks obeyed Beer s law while the 443 325 nm absorbance ratios remained essentially constant. When fruit extractor pressures were increased, the UV absorbance of the resulting juice increased and the 443 325 nm absorbance ratio decreased. Spectra of alcoholic solutions of the rag and albedo components... 

Fig. 5. Calculated temperatures in top smoke layer (Ts) and at the earth s surface (T.) for specific absorption cross sections of 1.1 and 22 rsf 1% aerosol in the visible. Assumed albedo at the earth s surface 30%.

Sulfur and sulfur compounds and their relationship to volcanic silicate rocks are at the heart of lo s surface chemistry. The satellite s low ultraviolet albedo combined with high visible and near-infrared reflectance suggested elemental sulfur to a number of researchers studying telescopic spectra (Wamsteker, 1973 Wamsteker et al., 1974), although laboratory measurements of pure sulfur differ somewhat from lo s average color. The presence of sulfur ions detected in Jupiter s magnetosphere near lo (Kupo et al., 1976) also pointed toward an lo source of sulfur. 

All of Neptune s six innermost satellites are very dark, having albedos of 0.065 or less. Proteus, the largest and outermost of the newly discovered satellites, had details on its surface imaged. It is heavily cratered, with a 93 mi (150 km) diameter crater visible there. Proteus turns out to be somewhat larger than Nereid and has a mean radius of 250 mi (400 km) images of Proteus indicate it to be decidedly non-spherical. The images indi-... 

Snow reflects light at all visible wavelengths and pure snow has an albedo in the visible and near UV in the range 0.96 to 0.98. In the IR, snow albedo is much lower, decreasing to values below 0.1 around 1500 and 2000 nm, so that the albedo of pure small-grained snow averaged over the solar spectrum is of the order of 0.8. ... 

Recent developments to measure snow SSA have allowed the testing of the relationship between SSA and optical properties. In the visible and UV, snow albedo is very high, so that the sensitivity to snow SSA is not large. In the IR this sensitivity is large and Domine et al. have recently established a quasi-linear relationship between SSA and snow albedo in the wavelength range 1650-2260 nm. Likewise, Simpson et al. observe a proportionality between the optical scattering coefficient of snow and its SSA. 

U. Feister, R. Grewe (1995). Spectral albedo measurements in the UV and visible region over different types of surfaces. Photochem. PhotobioL, 62,736-744. 

A visible mass of condensed water vapor particles or ice suspended above the Earth s surface. Clouds may be classified on their visible appearance, height, or form, cloud albedo... 

Sulphate aerosols scatter the light very strongly this has the effect not only of reducing the visibility but also of increasing the albedo of the atmosphere, i.e. its power to reflect the sun s rays these aerosols therefore contribute, like other particles, to cooling the planet and counterbalancing the greenhouse effect. 

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