November 26, 2012 - ANTARCTICA
- At first glance these beautiful images from the Antarctic appear to
show 50-ft tall waves that have been instantly frozen as they break.
Some people have posted the pictures online, taken by scientist Tony
Travouillon at Dumont D'Urville, with a description claiming they are a
tsunami wave which was frozen. But although email chains and internet
forums back this claim up, what is really pictured is the natural
phenomenon of blue ice.
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| Hard work: Mr Travouillon travelled to the Antarctic while studying for his PhD from the Australian university of New South Wales, between 2001-2004. Image: Tony Travouillon. |
These freezing blue towers were created when ice was compressed and the
trapped air bubbles were squeezed out. During the summer the surface ice
melts and new ice layers compress on top. The ice appears blue because
when when light passes through thick ice, blue light is transmitted back
out but red light is absorbed. If the bubbles were not compressed they
would scatter the light, meaning it would all be reflected back out and
it would appear white.
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| Imposing: Although this is not, as widely rumoured, a wave frozen while breaking, it is still an incredible phenomenon. Image: Tony Travouillon. |
Larry Gedney wrote about blue snow and ice on the Alaska Science Forum.
He explained: 'It takes an appreciable thickness of pure ice to absorb
enough red light so that only the blue is transmitted. You can see the
effect in snow at fairly shallow depths because the light is bounced
around repeatedly between ice grains, losing a little red at each
bounce. 'You can even see a gradation of colour within a hole poked in
clean, deep snow. Near the opening, the transmitted light will be
yellowish. 'As the depth increases, the corer will pass through
yellowish-green, greenish-blue and finally vivid blue. If the hole is
deep enough, the colour and light disappear completely when all the
light is absorbed.' - Daily Mail.
