Blue ice (glacial)
Blue ice occurs when snow falls on a glacier, is compressdf, and becomes part of a glacier that winds its way toward a body of water. During its travels, air bubbles that are trapped in the ice are squeeze out, and the size of the ice crystals increases, making it clear.
In some areas, earthquakes have raised the blue ice above the ground and created formations much like large frozen waves.
The blue color is sometimes wrongly attributed to Rayleigh scattering. Rather, ice is blue for the same reason water is blue: it is a result of an overtone of an oxygen-hydrogen (O-H) bond stretch in water which absorbs light at the red end of the visible spectrum.[1]
An example of blue ice was observed in Tasman Glacier, New Zealand in January 2011.[2]
Antarctic runways
Blue ice is exposed in areas of the Antarctic where there is no net addition or subtraction of snow. That is, any snow that falls in that area is counteracted by sublimation or other losses. These areas have been used as runways (e.g.Wilkins Runway, Novolazarevskaya, Patriot Hills Base Camp) due to their hard surface which is suitable for aircraft fitted with wheels rather than skis.
References
- ^ Braun, Charles L.; Smirnov, Sergei N. (August 1993). "Why Is Water Blue?". J. Chem. Edu., 1993, 70(8), 612. Dartmouth College. Retrieved 2013-12-22.
Water owes its intrinsic blueness to selective absorption in the red part of its visible spectrum. The absorbed photons promote transitions to high overtone and combination states of the nuclear motions of the molecule, i.e. to highly excited vibrations. To our knowledge the intrinsic blueness of water is the only example from nature in which color originates from vibrational transitions.
- ^ Harvey, Eveline (14 January 2011). "NZ blue ice sighting an unexpected treat for tourists". The New Zealand Herald. Retrieved 21 September 2011.
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