Icebergs are large masses of ice floating in the sea.
Development and origin
The icebergs in the North Atlantic are mainly from Greenland, those in the South Atlantic, however, mostly from Antarctica.
In general, they arise from the fact that large chunks of a glacier or ice shelf break; the glaciers calve. Icebergs are made of fresh water with air bubbles. Icebergs can also be formed from ice floes and pack ice auftürmendem; Then, small amounts of sea salt. Because of the density anomaly of water that is in the solid state is less dense than the liquid. Because of the surrounding compared to the water but only slightly lower density rises only about one-seventh of its bulk above the water surface. The hidden part of the iceberg keel called is underwater.
Danger to ships and characters for sea level rise
Icebergs are dangerous for ships, as a clash usually has a devastating effect on the ship. The largest part of the iceberg is under water and is therefore invisible - visible is only the proverbial "tip of the iceberg." The submerged body ( "Kiel" ) may be excessively extended in the horizontal direction, which can lead to misperceptions. Therefore, ships must necessarily maintain a significant safety margin. The largest contiguous with an iceberg ship disaster was the sinking of the Titanic in April 1912.
When icebergs break off in excessive amounts by the glaciers of Antarctica and Greenland from the mainland, it may mean that the polar ice is about to melt, the sea level rises globally. This is seen as a possible consequence of global warming. The thawing of already floating icebergs only leads to a small rise in sea level: has the melting water from the icebergs a lower density than the sea water, as the sea water, in contrast to melt water contains much more salt. By melting the density of the oceans will accordingly somewhat and hence the volume.
The first research
The Russian poet, scientist and polymath Mikhail Lomonosov told about in 1750 icebergs scientific and first time correct: Since the density of the ice 0.920 kg per liter ( sea water 1.025 kg / liter ), 90 % of the volume of icebergs must be positioned below the water surface. The average values may vary slightly depending on salinity and water temperature. The iceberg is still the amount of air bubbles added as a variable. Lomonosov grew up in North-West Russia to the White Sea, where she learned the basics of early seafaring, navigation and meteorology. Later he studied in Marburg, what the reason is probably that the word he Айсберг ( transcribed Aisberg ) coined in the Russian language.
Types and Characteristics
Icebergs that arise from Ice Shelf, are relatively flat and are therefore called tabular icebergs. They form the largest icebergs and are typical of the Antarctic.
In general, icebergs are white. The white color caused by the reflection of light at the air trapped in the ice. Often they are crossed by blue veins with clear ice. This ice is melting water that has penetrated into crevasses and later froze again. Occasionally, also blue and green icebergs. The cause of this coloration is still unknown. This is likely to sea ice that forms on the underside of the ice shelf. When the iceberg tip over, because has changed due to the melting its center of gravity, the staining is visible.
Icebergs last for an average of about three years, large specimens up to 30 years. You can have an area of over 10,000 square kilometers. The currently largest recorded iceberg, a Antarctic tabular iceberg has been spotted in 1956 in the South Pacific and was beginning to 31,000 km ². A well-known example of a giant iceberg B -15 with an original area about 11,600 km ². This was established in 2000 in the Ross Ice Shelf in 2002 and broke into several parts.
An iceberg that runs on base and thus over time is stationary, ice island (English ice Iceland ) is called. This is contrary to the word element is not an island. Well-known examples are Pobeda in Antarctica or the ice island at Ward Hunt Iceland in the far north of Canada. Such ice islands can endure for years, until the iceberg is melted so far that he will be released again and drift away. Occasionally, extra large free-floating icebergs are called ice islands.
Monitoring and protective measures
Depending on the size icebergs may also occur in subtropical zones to. They pose a threat to shipping and are monitored by satellites and aircraft. Icebergs can also extend to the seabed and damage in their locomotion pipelines and subsea completions for oil and gas production. Therefore, such investments are necessary dug in order to protect them from icebergs.
The monitoring of the movement of icebergs to secure shipping in the North Atlantic is carried out by the organization International Ice Patrol. In the Southern Ocean, this task is performed by the U.S. National Ice Center. This organization also awards the names for icebergs greater than 10 nautical miles (diameter in any direction). The name is composed of a letter indicating the area of origin and a running number in chronological order. The letters indicate the quadrant in which the iceberg was first discovered as follows: