Picture of the Day: The Multicolored Iceberg
THE MULTICOLORED ICEBERG
In this remarkable capture we see a multicolored striped iceberg spotted somewhere near Antarctica, about 2,700 km south of Cape Town, South Africa. This image along with a series of other amazing photos of icebergs and glaciers were the subject of popular email forwards many years back, often incorrectly labeled as icebergs in Lake Michigan or Huron.
While the location was incorrect, the phenomenon is indeed very real. There’s even a full report by Internet sleuth site Snopes.com on the email/pics.
So how does this multicolored striping happen? According to the Australian Government’s Antarctic Division:
“Icebergs are formed from the glacial ice that has built up from snow falling on the Antarctic continent over millennia. This ice consists of pure fresh water. The ice flows slowly to the coast and breaks off either from glaciers or from ice shelves. Because the ice shelves are very thick and are floating, the seawater beneath them interacts with the glacial ice.
As seawater is drawn deep under the ice shelves by the oceanic currents, it becomes supercooled. Under certain conditions it can freeze to the base of the ice shelf. Because this ice is formed from seawater, it differs from the freshwater ice of the ice shelf. Often, the frozen seawater contains organic matter and minerals, causing it to have a different colour and texture. Thus icebergs broken off from the ice shelves may show layers of the pure blue-white glacial ice and greener ice formed from frozen seawater. As the bergs become fragmented and sculpted by the wind and waves, the different coloured layers can develop striking patterns.
Pure glacial ice, too, can exhibit striking colour patterns. This is thought to be a result of melting that can occur on the continent before the bergs break off. Crevasses high on the Antarctic plateau can fill with melt water and then refreeze, producing layering of blue ice within a white ice matrix. After calving, they begin eroding and the alignment of the stripes can become irregular, leading to icebergs with spectacular appearances.
– Source: Australian Government: Antarctic Dvision
Additional causes for the colouration include brown sediment washing underneath the ice shelf and dead marine creatures such as krill becoming trapped in the ice.