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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.
'''[[Antarctica]]''' is Earth's southernmost continent. It contains the geographic [[South Pole]] and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the [[Antarctic Circle]], and is surrounded by the [[Southern Ocean]]. At 14,000,000 km2, it is the fifth-largest continent. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by [[ice]] that averages 1.9 kilometers in thickness, which extends to all but the northernmost reaches of the [[Antarctic Peninsula]].


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.
Antarctica has no indigenous population and there is no evidence that it was seen by humans until the 19th century. However, belief in the existence of a ''Terra Australis''—a vast continent in the far south of the globe to "balance" the northern lands of Europe, Asia and North Africa—had existed since the times of Ptolemy (1st century AD), who suggested the idea to preserve the symmetry of all known landmasses in the world. Even in the late 17th century, after explorers had found that South America and Australia were not part of the fabled "Antarctica", geographers believed that the continent was much larger than its actual size.


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.
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'''([[Iceberg|Full Article...]])'''

Latest revision as of 05:48, 2 May 2025

Antarctica (orthographic projection).png

Antarctica is Earth's southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14,000,000 km2, it is the fifth-largest continent. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 kilometers in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula.

Antarctica has no indigenous population and there is no evidence that it was seen by humans until the 19th century. However, belief in the existence of a Terra Australis—a vast continent in the far south of the globe to "balance" the northern lands of Europe, Asia and North Africa—had existed since the times of Ptolemy (1st century AD), who suggested the idea to preserve the symmetry of all known landmasses in the world. Even in the late 17th century, after explorers had found that South America and Australia were not part of the fabled "Antarctica", geographers believed that the continent was much larger than its actual size.

(Full Article...)