![]() This is because water molecules absorb other colors more efficiently than blue. Since glacial mass is affected by long-term climatic changes, e.g., precipitation, mean temperature, and cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level.Ī large piece of compressed ice, or a glacier, appears blue, as large quantities of water appear blue. However, within high-altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater. Many glaciers from temperate, alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. Glacial ice is the largest reservoir of fresh water on Earth, holding with ice sheets about 69 percent of the world's freshwater. The volume of glaciers, not including the ice sheets of Antarctica and Greenland, has been estimated at 170,000 km 3. Greenland and Patagonia also have huge expanses of continental glaciers. Continental glaciers cover nearly 13 million km 2 (5 million sq mi) or about 98% of Antarctica's 13.2 million km 2 (5.1 million sq mi), with an average thickness of ice 2,100 m (7,000 ft). Glaciers cover about 10% of Earth's land surface. With more than 7,000 known glaciers, Pakistan has more glacial ice than any other country outside the polar regions. Between latitudes 35°N and 35°S, glaciers occur only in the Himalayas, Andes, and a few high mountains in East Africa, Mexico, New Guinea and on Zard-Kuh in Iran. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions, but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. Ī glacier ( US: / ˈ ɡ l eɪ ʃ ər/ UK: / ˈ ɡ l æ s i ər, ˈ ɡ l eɪ s i ər/) is a persistent body of dense ice that is constantly moving under its own weight. The distance from left to right image border is c. To the right is an area with open crevasses where the glacier flows over a kind of large cliff. The mountain to the left is the Wildspitze (3.768 m), second highest in Austria. The Taschachferner in the Ötztal Alps in Austria. Glacier of the Geikie Plateau in Greenland. Persistent body of ice that is moving under its own weight
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