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ICEBERG

For other uses, see Iceberg (disambiguation).

An iceberg (a partial loan translation, probably from Dutch ijsberg (literally: mountain of ice),[1] 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 trouble is only a small manifestation of a larger problem.

Contents

Physiology

Iceberg Sizes[2]
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

  • 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.
  • 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.

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:

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 apart 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 history

There was no system in place before 1912 to track icebergs to guard against ship collisions. The sinking of the RMS Titanic, which caused the death of more than 1,500 of its 2,223 passengers, created the demand for a system to observe icebergs. For the remainder of the ice season of that year, the United States Navy patrolled the waters and monitored ice flow. In November 1913, The International Conference on the Safety of Life at Sea met in London to devise a more permanent system of observing icebergs. Within three months, the participating maritime nations had formed the International Ice Patrol (IIP). The goal of the IIP was to collect data on meteorology and oceanography in order to measure currents, iceflow, ocean temperature, and salinity levels. They published their first records in 1921, which allowed for a year-by-year comparison of iceberg movement.

New technologies continued to be deployed to help monitor icebergs. Aerial surveillance of the seas first took hold in the early 1930s, which allowed for the development of charter systems that could accurately detail the ocean currents and iceberg locations. In 1945 experiments were conducted to test the effectiveness of radar in detecting icebergs. A decade later numerous oceanographic monitoring outposts were established for the purpose of collecting data, that today, continued to serve an important role in environmental study. A computer was first installed on a ship for the purpose of oceanographic monitoring in 1964, which allowed for a faster evaluation of data. By the 1970s, Icebreaking ships were equipped with automatic transmission of satellite photographs of ice in Antarctica. Systems for optical satellites had been developed, but at this point were still limited by weather conditions. In the 1980s, drifting buoys were used in Antarctic waters for oceanographic and climate research. They are equipped with sensors that measure ocean temperature and currents. Side-Looking Airborne Radar (SLAR) made it possible to acquire images regardless of weather conditions. On 4 November 1995, Canada launched RADARSAT-1. Developed by the Canadian Space Agency, it provides images of Earth for both scientific and commercial purposes. This system was the first to use Synthetic Aperture Radar (SAR), which sends microwave energy to the ocean surface and records the reflections. The European Space Agency launched ENVISAT on 1 March 2002, an environmental satellite which uses Advanced Synthetic Aperture Radar (ASAR). This can detect changes in surface height with a high degree of accuracy. The Canadian Space Agency is currently readying RADARSAT-2, which is scheduled to be launched in December 2006. It will utilize SAR and multipolarization modes and will follow the same orbit path as RADARSAT-1.[3]

References

  1. ^ Online Etymology Dictionary. (URL accessed March 29, 2006).
  2. ^ Canadian Geographic–Profile: IJsberg. (URL accessed March 29, 2006
  3. ^ Canadian Geographic–Tracking Monsters. (URL accessed March 29, 2006).

See also

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External links