This spectacular series of images circulates via email and has also been posted on various websites, blogs and online forums. A description commonly included with the images claims that they depict a large tidal wave or tsunami wave instantly frozen as it breaks. However, the ice formation shown in the images is not an instantly frozen wave.
The photographs were taken by scientist Tony Travouillon in Antarctica. Many of the images can be seen in a gallery on Travouillon's website. The pictures do not show a giant wave somehow snap-frozen in the very act of breaking. The formation contains blue ice, and this is compelling evidence that it was not created instantly from a wave of water. Blue ice is created as the ice is compressed and trapped air bubbles are squeezed out. The ice looks blue because, when light passes through thick ice, blue light is transmitted back out but red light is absorbed. An article on the Alaska Science Forum notes:
The color of ice can be used to estimate its strength and even how long it has been frozen. Arctic Ocean ice is white during its first year because it is full of bubbles. Light will travel only a short distance before it is scattered by the bubbles and reflected back out. As a result, little absorption occurs, and the light leaves with the same color it had when it went in.
During the summer, the ice surface melts and new overlying ice layers compress the remaining air bubbles. Now, any light that enters travels a longer distance within the ice before it emerges. This gives the red end of the spectrum space enough to be absorbed, and the light returned at the surface is blue.
Arctic explorers and mountain climbers know that old, blue ice with fewer bubbles is safer and stronger than white ice. An added bonus for explorers is knowing that floating camps built on blue ice will last longer.
Thus, the deep blue colour suggests that the ice in the formation was built up slowly over time rather than formed instantly. Subsequent melting and refreezing over many seasons has given the formation its smooth, wave-like appearance.
No comments:
Post a Comment