explain glaciers and ocean currents in long type
Answers
There are several types of glacier, based on their shape, where they are, or where they come from. The biggest types of glacier are called continental ice sheets and ice caps. They often totally cover mountains. ... When glaciers flow into flat, lowland areas, the ice spreads out to form piedmont glaciers.
There are many types of currents such as those driven by salinity, wind, temperature or the Coriolis effect. Two of the most commonly identified are surface currents and deep ocean currents.
Answer:
A glacier is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. Glaciers slowly deform and flow under stresses induced by their weight, creating crevasses, seracs, and other distinguishing features. They also abrade rock and debris from their substrate to create landforms such as cirques, moraines, or fjords. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that forms on the surface of bodies of water.
Fox Glacier in New Zealand finishes near a rainforest.
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. 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.[2] With more than 7,000 known glaciers, Pakistan has more glacial ice than any other country outside the polar regions.[3][1] Glaciers cover about 10% of Earth's land surface. Continental glaciers cover nearly 13 million km2 (5 million sq mi) or about 98% of Antarctica's 13.2 million km2 (5.1 million sq mi), with an average thickness of 2,100 m (7,000 ft). Greenland and Patagonia also have huge expanses of continental glaciers.[4] The volume of glaciers, not including the ice sheets of Antarctica and Greenland, has been estimated at 170,000 km3.[5]
Glacial ice is the largest reservoir of fresh water on Earth.[6] 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. Within high-altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater.
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.
A large piece of compressed ice, or a glacier, appears blue, as large quantities of water appear blue. This is because water molecules absorb other colors more efficiently than blue. The other reason for the blue color of glaciers is the lack of air bubbles. Air bubbles, which give a white color to ice, are squeezed out by pressure increasing the density of the created ice.
Classification by size, shape and behavior
Glaciers are categorized by their morphology, thermal characteristics, and behavior. Alpine glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier, or alternatively an alpine glacier or mountain glacier.[8] A large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field.[9] Ice caps have an area less than 50,000 km2 (19,000 sq mi) by definition.
Glacial bodies larger than 50,000 km2 (19,000 sq mi) are called ice sheets or continental glaciers.[10] Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland.[11] They contain vast quantities of fresh water, enough that if both melted, global sea levels would rise by over 70 m (230 ft).[12] Portions of an ice sheet or cap that extend into water are called ice shelves; they tend to be thin with limited slopes and reduced velocities.[13] Narrow, fast-moving sections of an ice sheet are called ice streams.[14][15] In Antarctica, many ice streams drain into large ice shelves. Some drain directly into the sea, often with an ice tongue, like Mertz Glacier.
Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica, Baffin and Ellesmere Islands in Canada, Southeast Alaska, and the Northern and Southern Patagonian Ice Fields. As the ice reaches the sea, pieces break off, or calve, forming icebergs. Most tidewater glaciers calve above sea level, which often results in a tremendous impact as the iceberg strikes the water. Tidewater glaciers undergo centuries-long cycles of advance and retreat that are much less affected by climate change than those of other glaciers.[16]