by John Adam
"The photo above shows a chunk of scalloped ice, about 65 ft in width that broke off from the Sawyer Glacier near Tracy Arm Fjord in southeastern Alaska. Note the pure blue color emanating from within the “chasm.” The mechanism responsible for producing this robin’s egg blue color, as well as the blue color in deep snow, is essentially the same as that giving deep water its blue color. The longer wavelengths (yellow and red light) present in the incident white sunlight are preferentially absorbed by ice crystals. As a result, what we see is what’s not absorbed -- reflected light that’s dominated by the green and blue portion of the spectrum. In general, the thicker the ice the greater the absorption, and thus the bluer the color."
