Figure 4. A sunset on the coast of Sri Lanka at Colombo, November, 1988. One can clearly see the strong yellow-orange presence in the direct sunlight. This results from greater scattering of blue-violet wavelengths as the path length of sunlight through the earth's atmosphere increases towards sundown. It is evident that the use of direct sunlight (as opposed to skylight) just after sunrise or before sundown could definitely enhance the appearance of yellow, orange and red stones. Photo:  Richard W. Hughes .
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