Iceberg
An
iceberg (a partial
loan translation, probably from
Dutch ijsberg (literally:
mountain of ice),
[Online Etymology Dictionary. (URL accessed March 29, 2006).] 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/m
3, and that of
sea water ca. 1025 kg/m
3, 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.
Iceberg Sizes[Canadian Geographic–Profile: IJsberg. (URL accessed March 29, 2006] | | 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.
*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)
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.
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 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.
[Canadian Geographic–Tracking Monsters. (URL accessed March 29, 2006).]
|
Tabletop icebergs at sunrise in Antarctica |
*
Icebreaker*
Project Habakkuk, a British project to build
aircraft carriers of ice-like
Pykrete.
*
Iceberg Finder Service for east coast of Canada.
