Explained: The science behind iceberg formation
It is not often one sees an iceberg underwater like you do in Ice Age movies and other animated programmes. Like penguins and the snowy-white polar bears, icebergs are the natural symbols associated with the polar regions. Sheets of snow floating in the water and blocks of ice deep into the sea are all part of the landscape of chilly polar regions. Have you ever wondered how these icebergs and snow shelves come into existence?
What is an iceberg?
The origin of the word comes from the Dutch word ‘ijsberg’ where ijs means ice and berg means a mountain. It is also partly derived from the Norwegian and Swedish word ‘isberg’. An iceberg is a fragment of a glacier or shelf ice made by the process of calving or splitting, that which is floating in open water. For a floating block of ice to be classified as an iceberg, it must be 16 feet or more above sea level and more than 98 feet wide in construction. The total ice coverage must be over 5,382 feet. Icebergs come in various sizes ranging from ‘bergy bits’ that are not bigger than 5 meters and ‘growlers’ that are under 1 metre. Some ‘pan icebergs’ can be as large as a country and other smaller floating piece of ice are called ‘brash ice’. The best places to see icebergs are in the Northern Hemisphere of Greenland, Antarctica, the ‘iceberg valley’ of Newfoundland in Canada, Alaska, Iceland, and New Zealand.
Types of iceberg
Icebergs can be classified into tabular and non-tabular forms depending on their shapes. A tabular iceberg is generally flat at the top and steep towards the sides whereas, a non-tabular iceberg is without a flattened top and can include shapes such as wedges, pinnacles, dry rocks, blocks, and domes. They can reach up to a height of 300 feet above the water's surface and weigh up to ten million tonnes. Icebergs can float on the water despite the size and weight because they have a lower density than the surrounding water. The most interesting fact is that the visible part of the iceberg that we usually see is only 10% of the total structure that is hidden underwater.
The formation of icebergs
There would indeed be no icebergs without the presence of glaciers. Icebergs are formed by the accumulation of snow on a bedrock, island, or piece of land. The enormous size and density of the iceberg are what assist its movement in sliding into the sea through gravity’s force. Every year, an iceberg grows by a few centimetres to a few kilometers.
The formation is dependent on the steepness of the slope at which a glacier is placed. When a glacier is exposed to wind, tides, and currents the ice in front of it breaks off releasing chunks of ice into the water. This phenomenon is called ‘calving’. Icebergs travel with winds and water currents, sometimes getting caught in shallow waters or near the shore. This happens because the maximum structure of the iceberg is beyond the waterline. When an iceberg reaches warm waters, it is attacked from all sides by the new temperature, some of the ice melts in the process, creating ‘melt ponds.’ These can trickle through the icebergs creating cracks.
Glaciers take thousands of years to form on land by the accumulation of snow, each layer of snow may get affected by wind or currents releasing chunks of snow into the water, forming icebergs of various shapes and sizes. Large icebergs that break from the front of the glacier and slip onto the glacier face can shift the glacier back for a few minutes, causing earthquakes that give off energy equivalent to an atomic bomb.