Knowledge Station: The mystery behind floating icebergs
Puzzle: They float like an island but you can’t live there.
Be it the great story of sunken ship Titanic or fun narration of Penguins movie, icebergs have captured human imagination for ages. How they form and survive and how they are an ecosystem in themselves, is all a great mystery to a common mind. Recently, it was reported that a vast iceberg — almost the size of Greater London — broke away from the Antarctic Brunt Ice Shelf. This breaking away from the 150-metre-thick Brunt Ice Shelf process is called “calving”.
And while you may be worried about global warming, you must know that more icebergs are being formed already. Before we start reading more about this amazing natural phenomenon here’s a fun activity for you.
Draw an iceberg and see how it floats on water:
- Icebergs are found in the Arctic, North Atlantic, and Southern Oceans. Icebergs float in salt water because they are formed by calving, or splitting, glaciers and are thus made of fresh water. The size of icebergs varies widely.
- Small bergs (a little smaller than a car) are known as “growlers,” while slightly larger bergs (about the size of a house) are called”bergy bits.” Larger bergs are classified as small, medium, large, and very large. And very large they can be.
- The tallest known iceberg in the North Atlantic was 550 feet (168 m) above sea level. Since the bulk of an iceberg is below the water, the entire berg was estimated to be as tall as a 55-story building!
- Icebergs are also classified by their shape. Tabular icebergs have steep sides and a flat top like a plateau, while non-tabular icebergs include irregular shapes such as rounded tops, spires, sloping sides, and blocks. Wind and water erode icebergs into amazing sculptural shapes.
- Most icebergs are white, but some may appear blue or even green. Ice is full of tiny air bubbles that scatter all colour wavelengths the same amount, giving the ice a white appearance. If the ice is compressed, the bubbles are squeezed out and the blue light is scattered much more than other colours – making the ice appear blue.
- You know that Algae often grow on the underside of sea ice and icebergs, producing green stripes that are only revealed when the ice rolls over and exposes the previously underwater sections.
- And yes, icebergs also have a life cycle. They begin as part of a glacier, building for tens of thousands of years and slowly moving toward the ocean. Once an iceberg calves, it typically lasts for three to six years. Some icebergs simply melt away, while others collapse more violently. Some icebergs never move into warmer waters and may last 50 years or more.
- Icebergs support an ecosystem of their own. Algae survive, and many fish too live in and around icebergs.
- Such mysterious floating pieces can be intimidating. No wonder an Ice Patrol, under US Coastguards, works in North America to keep a close watch over the area off the coast of Newfoundland, known as Iceberg Alley because of the high number of icebergs found in the waters.