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[[File:Antarctic Sound-2016-Iceberg 02.jpg|450px|thumb|Iceberg floating in the Antarctic Sound]] | [[File:Antarctic Sound-2016-Iceberg 02.jpg|450px|thumb|Iceberg floating in the Antarctic Sound]] | ||
An '''iceberg''' is a large piece of freshwater [[ice]] that has broken off a [[glacier]] or an [[ | An '''iceberg''' is a large piece of freshwater [[ice]] that has broken off a [[glacier]] or an [[Ice-shelf|ice shelf]] and is floating freely in open water. It may subsequently become frozen into [[pack ice]] (one form of sea ice). As it drifts into shallower waters, it may come into contact with the seabed, a process referred to as seabed gouging by ice. About 90% of an iceberg is below the surface of the water. | ||
==Etymology== | ==Etymology== | ||
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Because the density of pure [[ice]] is about 920 kg/m3, and that of seawater about 1025 kg/m3, typically about one-tenth of the volume of an iceberg is above water (which follows from Archimedes's Principle of buoyancy). The shape of the underwater portion can be difficult to judge by looking at the portion above the surface. This has led to the expression "tip of the iceberg", for a problem or difficulty that is only a small manifestation of a larger problem. | Because the density of pure [[ice]] is about 920 kg/m3, and that of seawater about 1025 kg/m3, typically about one-tenth of the volume of an iceberg is above water (which follows from Archimedes's Principle of buoyancy). The shape of the underwater portion can be difficult to judge by looking at the portion above the surface. This has led to the expression "tip of the iceberg", for a problem or difficulty that is only a small manifestation of a larger problem. | ||
The altitudes of the tips of icebergs typically range from 1 to 75 meters (3.3 to 246.1 ft) above sea level and weigh 100,000 to 200,000 metric tons (110,000 to 220,000 short tons). The largest known iceberg in the North Atlantic was 168 meters (551 ft) above sea level, reported by the USCG icebreaker ''East Wind'' in 1958, making it the height of a 55-story building. These icebergs originate from the glaciers of western Greenland and may have interior temperatures of −15 to −20 °C (5 to −4 °F). | The altitudes of the tips of icebergs typically range from 1 to 75 meters (3.3 to 246.1 ft) above sea level and weigh 100,000 to 200,000 metric tons (110,000 to 220,000 short tons). The largest known iceberg in the North Atlantic was 168 meters (551 ft) above sea level, reported by the USCG [[icebreaker]] ''East Wind'' in 1958, making it the height of a 55-story building. These icebergs originate from the glaciers of western Greenland and may have interior temperatures of −15 to −20 °C (5 to −4 °F). | ||
Winds and currents tend to move icebergs close to the coast. The largest icebergs recorded have been calved, or broken off, from the [[Ross Ice Shelf]] of [[Antarctica]]. Iceberg B-15, photographed by satellite in 2000, measured 295 by 37 kilometers (183 by 23 mi), with a surface area of 11,000 square kilometers (4,200 sq mi). The largest iceberg on record was an Antarctic tabular iceberg of over 31,000 square kilometers (12,000 sq mi) [335 by 97 kilometers (208 by 60 mi)] sighted 150 miles (240 km) west of Scott Island, in the South Pacific Ocean, by the USS ''Glacier'' on November 12, 1956. This iceberg was larger than Belgium. | Winds and currents tend to move icebergs close to the coast. The largest icebergs recorded have been calved, or broken off, from the [[Ross Ice Shelf]] of [[Antarctica]]. Iceberg B-15, photographed by satellite in 2000, measured 295 by 37 kilometers (183 by 23 mi), with a surface area of 11,000 square kilometers (4,200 sq mi). The largest iceberg on record was an Antarctic tabular iceberg of over 31,000 square kilometers (12,000 sq mi) [335 by 97 kilometers (208 by 60 mi)] sighted 150 miles (240 km) west of Scott Island, in the South Pacific Ocean, by the USS ''Glacier'' on November 12, 1956. This iceberg was larger than Belgium. | ||