Iceberg
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An iceberg (a partial loan translation, probably to Dutch ijsberg,<ref>Online Etymology Dictionary. (URL accessed March 29, 2006).</ref> cognate to German Eisberg) is a large piece of ice that has broken off from a snow-formed glacier or ice shelf and is floating in open water.
Since the density of pure water ice is ca. 920 kg/m3, and that of sea water ca. 1025 kg/m3, typically, around 90% of the volume of an iceberg is under water, and that portion's shape can be difficult to surmise from looking at what is visible above the surface. This has led to the expression "tip of the iceberg", generally applied to a problem or difficulty, meaning that the problem is only a small manifestation of a larger trouble.
Contents |
Physiology
| Iceberg Sizes<ref>Canadian Geographic–Profile: IJsberg. (URL accessed March 29, 2006</ref> | ||
|---|---|---|
| Height (m) | Width (m) | |
| Growler | less than 1 | less than 5 |
| Bergy Bit | 1 to 4 | 5 to 14 |
| Small | 5 to 15 | 15 to 60 |
| Medium | 16 to 45 | 61 to 122 |
| Large | 46 to 75 | 123 to 213 |
| Very Large | over 75 | over 213 |
The mass can be very durable and can easily damage sheet metal. As a result of these factors, icebergs are considered extremely dangerous hazards to shipping. The most famous sinking from an iceberg collision was the destruction of the RMS Titanic on April 14, 1912
Facts
Image:Carlb-newfoundland-iceberg-2002.jpg
- Common name: Iceberg, Berg, Bergie
- Scientific name: Arctic iceberg
- Average height: ranges from one metre above sea level to more than 75 metres above sea level.
- Icebergs are comprised of pure fresh water.
- The glaciers of western Greenland, where 90% of Newfoundland's icebergs originate, are amongst the fastest moving in the world, up to seven kilometres per year.
- Between 10,000 to 15,000 icebergs are calved each year.
- The glacial ice that icebergs are made of may be more than 15,000 years old.
- Seven-eighths of the iceberg's mass is below water.
- The average iceberg weight for the Grand Banks area is 100 000 to 200 000 tonnes and is about the size of a cubic 15-storey building.
- The interior temperature of icebergs off the coast of Newfoundland and Labrador is in the range of −15 to −20°C.
- Ninety-three percent of the world's mass of icebergs is found surrounding the Antarctic.
- The tallest known iceberg in the North Atlantic was 168 metres high.
(Source: Canadian Geographic Just the facts)
History
The first to explain the formation of icebergs was the Russian peasant prodigy Mikhail Lomonosov. In the 20th century, several scientific bodies were established to study and monitor the icebergs. The International Ice Patrol, formed in 1914 in response to the Titanic disaster, monitors iceberg dangers near the Grand Banks of Newfoundland and provide the "limits of all known ice" in that vicinity to the maritime community.
Image:CHC Bell 212 Iceberg Labrador.jpg
Monitoring
Icebergs are monitored worldwide by the U.S. National Ice Center (NIC), established in 1995, which produces analyses and forecasts of Arctic, Antarctic, Great Lakes, and Chesapeake Bay ice conditions. More than 95% of the data used in its sea ice analyses are derived from the remote sensors on polar-orbiting satellites that survey these remote regions of the Earth.
The NIC is the only organization that names and tracks all Antarctic Icebergs. It assigns each iceberg larger than 10 nautical miles (18 km) along at least one axis a name composed of a letter indicating its point of origin and a running number. The letters used are as follows:
- A – longitude 0° to 90° W (Bellingshausen Sea, Weddell Sea)
- B – longitude 90° W to 180° (Amundsen Sea, Eastern Ross Sea)
- C – longitude 90° E to 180° (Western Ross Sea, Wilkesland)
- D – longitude 0° to 90° E (Amery Ice Shelf, Eastern Weddell Sea)
Iceberg B15, which calved from the Ross Ice Shelf in 2000 and initially had an area of 11 000 km², was the largest iceberg ever recorded. It broke in two in November 2002. The largest remaining piece of it, iceberg B-15A, with an area of 3000 km², was still the largest iceberg on Earth until it ran aground and split into several pieces late in October 2005.
Technology timeline
1912: Prior to 1912, there was no system to track icebergs or guard ships against collisions with floating ice. The tragic fate of the "unsinkable" RMS Titanic, and the loss of more than 1,500 lives, led to demands for an iceberg observation system. For the remainder of the 1912 ice season, the United States Navy patrolled the waters of the Grand Banks and detailed the shifting positions of southerly ice flow.
1913: The International Conference on the Safety of Life at Sea convened in London, England, in November to develop a more permanent iceberg observation system.
1914: Within three months of the conference, the participating maritime nations agreed to monitor the icebergs on several fronts and the International Ice Patrol (IIP) was born. The IIP was established with the mandate to collect data on meteorology and oceanography in order to measure ocean currents, ice drift, salinity levels, and ocean temperatures.
1921: The IIP published its first annual recordings, allowing for a year-to-year comparison of iceberg flow.
Early 1930s: Aerial surveillance took flight and charting systems were developed in order to provide detailed information regarding ocean currents and the location of icebergs.
1945: Experiments were conducted to determine the effectiveness of radar detection of floating ice and technological developments were soon underway.
1955: A series of oceanographic observation outposts were established aboard light stations and lightships]. Today, these outposts remain integral to the collection of data for the purpose of evaluating environmental behaviours such as global warming.
1964: For the first time, a computer was installed on an oceanographic ship. This allowed for more rapid evaluations of iceberg-related data.
1970s: Icebreaking ships became equipped with automatic picture transmission that enabled the ships to receive satellite photographs of ice in Antarctica. Optical satellite systems were developed but their capabilities were limited by weather conditions.
1980s: Drifting buoys were determined to be integral for oceanographic and climate research and were distributed throughout the Antarctic waters. These "drifters" are equipped with sensors and measure sea temperature as well as ocean currents. Side-Looking Airborne Radar (SLAR) also became invaluable to iceberg recognizance operations because of its ability to acquire images regardless of weather conditions.
1995: RADARSAT-1, Canada's first commercial earth observation satellite, was launched on Nov. 4. The satellite was developed by the Canadian Space Agency and provides images of Earth for both scientific and commercial uses. This satellite system was the first to use Synthetic Aperture Radar (SAR) which transmits microwave energy onto the ocean surface and then records the reflections.
2002: The European Space Agency launched ENVISAT, an environmental satellite equipped with Advanced Synthetic Aperture Radar (ASAR). ASAR can detect changes in surface heights with submillimetre precision.
Today: The Canadian Space Agency is managing the development of RADARSAT-2, which is scheduled to launch in December 2006. RADARSAT-2 will use SAR and multipolarization modes and will follow the same orbit path as RADARSAT-1.<ref>Canadian Geographic–Tracking Monsters. (URL accessed March 29, 2006).</ref>
References
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See also
- Icebreaker
- Project Habbakuk, a British project to build aircraft carriers of ice-like Pykrete.
- Images:
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