![]() He made a quick U-turn and signaled our buddy dinghy to follow. The captain also seemed excited when he saw where I was pointing. “Can we go back to that one, the one with the hole in it?” I asked. Our captain hadn’t noticed the iceberg he motored by without a glance. ![]() Not only was it a gorgeous blue hue, it also had an almost perfectly circular hole at its base. The bay was choked with icebergs ranging from tiny to gargantuan, but it was this mid-size one that caught my attention. Our two rubber Zodiacs set off one morning to cruise around Cierva Cove. This blue iceberg is one of my favorite photos from Antarctica. Professor Warren said icebergs are not only beautiful, but can help scientific research.As I close my series on Antarctica, I’d like to offer one more image of this dramatic destination. These are created by the intrusion of seawater into vertical cracks, which occur in the ice shelf as it breaks away from land.Īs seawater floods up to fill cracks in the cold, light-coloured glacier ice, it freezes into a dark stripe. Last but not least, there are striped icebergs, which are also unique to Antarctica. ![]() "The exact colour of these marine icebergs will depend on how much organic matter and iron oxide was in the seawater at the time," said Professor Warren, adding that the number of cracks in the iceberg also play a role. Longer wavelengths are favoured, so we see darker and greener colours. Together with the red iron particles, these cause a shift in the colour of light scattered by the iceberg. Seawater also contains dissolved yellow organic matter from dead plankton cells. Nature's palette for these icebergs comes from the sea, and from the movement of the ice sheet across the Antarctic continent.Īs an ice sheet passes towards the sea, it grinds the Antarctic bedrock creating a red iron-rich dust called "glacial rock flour", which falls into the ocean. "Marine ice contains not just ice but tiny particles that give it colour," said Professor Warren. This "marine ice" can actually come in various shades from green to blue, depending on what it contains. Instead, they are made of frozen seawater, which freezes to the underside of the ice shelf floating above it.Ī jade-coloured iceberg near Mawson Base, Australian Antarctic Territory ( Getty: Richard McManus) These icebergs are clear because, unlike glacier ice, they don't contain any bubbles. "You can see 10 metres down into the ice." "They are so immediately obvious when you are just looking at them because they are dark and clear," said Professor Warren, who has been on two Antarctic expeditions to study icebergs. Mysterious green icebergsĪntarctica is home to some of the most enigmatic icebergs of all time - like dark icebergs the colour of jade or emerald green, which have puzzled ship captains for the best part of a century. In ice, this results in red wavelengths being absorbed, with only blue light being scattered and escaping the iceberg. The fewer bubbles there are, the less chance there is of light being scattered. Where there are a lot of bubbles and snow particles in the iceberg, all wavelengths of light are scattered before they get absorbed, and so we see a bright white colour. Blue glacier ice in Alaska ( Getty: James + Courtney Forte)Īs the light hits snow particles or bubbles, it hits a boundary between ice and air and is bent and scattered.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |