1.
International Permafrost Association
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The IPA became an Affiliated Organisation of the International Union of Geological Sciences in July 1989. Permafrost or perennially frozen ground is defined as material that remains at or below 0 °C for at least two consecutive years. As such, upwards of 25% of Planet Earth is underlain to some degree by permafrost, Permafrost occurs in the high latitudes and mountains and plateaus of both hemispheres. International conferences were held at, West Lafayette, Indiana, U. S. A, yakutsk, Siberia, Edmonton, Canada, Fairbanks, Alaska, Trondheim, Norway, Beijing, China, Yellowknife, Canada, and Zurich, Switzerland. The Ninth International Conference on Permafrost was held in Fairbanks, Alaska, June 29-July 3,2008, the Eleventh International Conference on Permafrost will be held in Potsdam, Germany in 2016. Field excursions are a part of each Conference, and are organised by the host country. Regional conferences are organised between the main conferences, membership is through adhering national or multinational organisations or as Associate Members in countries where no Adhering Body exists. News from the IPA members are posted on the IPA webpage, ma Wei The Executive Director is Dr. Inga May. There are ten Working Groups, each with two co-chairs and some with subgroups, the International Secretariat is based at the Alfred Wegener Institute for Polar and Marine Research under the direction of Dr. Inga May. Annual membership contributions are used for producing and distributing Frozen Ground, proceedings of peer-reviewed papers are produced for each International Permafrost Conference by the host country, as are field trip guidebooks. A list of publications is found on the IPA website, the News Bulletin Frozen Ground is published annually and has a distribution of over 2500. Current and back issues are posted online, the Circum-Arctic Map of Permafrost and Ground-Ice Conditions at a scale of 1,10,000,000 was prepared by an international team and published in the Circum-Pacific map series in 1997. The CAPS, Circumpolar Active-Layer Permafrost System, version 2.0 CD-ROM is a compilation of global frozen ground data, Permafrost and Frozen Ground, Bibliography 1978 –2003, Glaciological Data Report GD-31, is an online bibliography of the world’s literature. Both are produced in conjunction with the International Permafrost Conferences and available from the National Snow, an illustrated Glossary of Permafrost and Related Ground-Ice Terms in 12 languages,278 pages, was produced in 1998. IPA cooperates with the American Geological Institute by providing literature to its Cold Regions Bibliography Project, the IPA coordinates and cooperates with several other major international programmes and organizations. Briefly these are, Global Terrestrial Network for Permafrost is a WMO network for monitoring of the active layer, the Circumpolar Active Layer Monitoring program has 125 reporting stations and TSP has identified over 800 boreholes, both include a total of over 15 participating countries. The IPA is collaborating with the International Union for Quaternary Research, the IPA has a Memorandum of Understanding with the Climate and Cryosphere programme of the World Climate Research Programme. The main areas of cooperation are on the roles of permafrost on water and carbon balances, beginning in 1995 the IPA and the International Geographical Union developed an Agreement of Cooperation, thus making IPA an affiliate of the IGU
2.
Ice lens
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An ice lens or ice lenses are formed when moisture, diffused within soil or rock, accumulates in a localized zone. Ice lenses grow parallel to the surface and several centimeters to several decimeters deep in the soil or rock, studies between 1990 and present have demonstrated that rock fracture by ice segregation is a more effective weathering process than the freeze-thaw process which older texts proposed. Ice lenses play the key role in frost induced heaving of soils and fracture of bedrock, frost heaving creates debris and dramatically shapes landscapes into complex patterns. Rock fracture in periglacial regions has often attributed to the freezing and volumetric expansion of water trapped within pores. However the majority of frost heaving and of bedrock fracture results instead from ice segregation in ice lenses in the frozen regions. Ice segregation results in rock fracture and frost heave, frost heave is the process by which the freezing of water-saturated soil causes the deformation and upward thrust of the ground surface. This process can distort and crack pavement, damage the foundations of buildings, moist, fine-grained soil at certain temperatures is most susceptible to frost heaving. Frost heave is common in arctic tundra because the permafrost maintains ground frozen at depth and prevents snowmelt, as a result, conditions are optimal for deep ice lens formation with large ice accumulations and significant soil displacement. Differential frost heave producing complex patterns will occur if the correct conditions exist, feedback from one years frost heave influences the effects in subsequent years. For example, a increase in overburden will affect the depth of ice formation. Time-dependent models of the frost heave indicate that over a long period the short-separation perturbations damp out, while mid-range perturbations grow. Bands of sediment or glacial till have been observed below Antarctic ice sheets, in the faster flowing glacial regions, the ice sheet is sliding over water saturated sediments or actually being floated upon a layer of water. The till and water served to reduce friction between the base of the ice sheet and the bedrock and these subglacial waters come from surface water which seasonally drains from melting at the surface, as well as from ice-sheet base melting. Ice lens growth within the bedrock below the glacier is projected during the months when there is ample water at the base of the glacier. Ice lenses will form within the bedrock, accumulating until the rock is sufficiently weakened that it shears or spalls off, layers of rock along the interface between glaciers and the bedrock are freed, producing much of the sediments in these basal regions of glaciers. Since the rate of movement is dependent upon the characteristics of this basal ice. The term premelting is used to describe the reduction in the temperature which results from the surface curvature of water thats confined in a porous medium. Premelted water exists as a layer on the surface of ice
3.
Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
4.
Rock (geology)
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Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
5.
Soil
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Soil is a mixture of minerals, organic matter, gases, liquids, and countless organisms that together support life on Earth. Soil is called the Skin of the Earth and interfaces with the lithosphere, the hydrosphere, the atmosphere, the term pedolith, used commonly to refer to the soil, literally translates ground stone. Soil consists of a phase of minerals and organic matter, as well as a porous phase that holds gases. Accordingly, soils are often treated as a system of solids, liquids. Soil is a product of the influence of climate, relief, organisms, Soil continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness soil has been considered as an ecosystem by soil ecologists. Most soils have a dry bulk density between 1.1 and 1.6 g/cm3, while the particle density is much higher. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, Soil science has two basic branches of study, edaphology and pedology. Edaphology is concerned with the influence of soils on living things, pedology is focused on the formation, description, and classification of soils in their natural environment. In engineering terms, soil is referred to as regolith, or loose material that lies above the solid geology. Soil is commonly referred to as earth or dirt, technically, as soil resources serve as a basis for food security, the international community advocates its sustainable and responsible use through different types of soil governance. Soil is a component of the Earths ecosystem. The worlds ecosystems are impacted in far-reaching ways by the carried out in the soil, from ozone depletion and global warming, to rainforest destruction. Following the atmosphere, the soil is the next largest carbon reservoir on Earth, as the planet warms, soils will add carbon dioxide to the atmosphere due to its increased biological activity at higher temperatures. Thus, soil carbon losses likely have a positive feedback response to global warming. Since soil has a range of available niches and habitats. A gram of soil can contain billions of organisms, belonging to thousands of species, mostly microbial, Soil has a mean prokaryotic density of roughly 108 organisms per gram, whereas the ocean has no more than 107 procaryotic organisms per milliliter of seawater. Since plant roots need oxygen, ventilation is an important characteristic of soil and this ventilation can be accomplished via networks of interconnected soil pores, which also absorb and hold rainwater making it readily available for plant uptake
6.
Latitude
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In geography, latitude is a geographic coordinate that specifies the north–south position of a point on the Earths surface. Latitude is an angle which ranges from 0° at the Equator to 90° at the poles, lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude is used together with longitude to specify the location of features on the surface of the Earth. Without qualification the term latitude should be taken to be the latitude as defined in the following sections. Also defined are six auxiliary latitudes which are used in special applications, there is a separate article on the History of latitude measurements. Two levels of abstraction are employed in the definition of latitude and longitude, in the first step the physical surface is modelled by the geoid, a surface which approximates the mean sea level over the oceans and its continuation under the land masses. The second step is to approximate the geoid by a mathematically simpler reference surface, the simplest choice for the reference surface is a sphere, but the geoid is more accurately modelled by an ellipsoid. The definitions of latitude and longitude on such surfaces are detailed in the following sections. Lines of constant latitude and longitude together constitute a graticule on the reference surface, latitude and longitude together with some specification of height constitute a geographic coordinate system as defined in the specification of the ISO19111 standard. This is of importance in accurate applications, such as a Global Positioning System, but in common usage, where high accuracy is not required. In English texts the latitude angle, defined below, is denoted by the Greek lower-case letter phi. It is measured in degrees, minutes and seconds or decimal degrees, the precise measurement of latitude requires an understanding of the gravitational field of the Earth, either to set up theodolites or to determine GPS satellite orbits. The study of the figure of the Earth together with its field is the science of geodesy. These topics are not discussed in this article and this article relates to coordinate systems for the Earth, it may be extended to cover the Moon, planets and other celestial objects by a simple change of nomenclature. The primary reference points are the poles where the axis of rotation of the Earth intersects the reference surface, the plane through the centre of the Earth and perpendicular to the rotation axis intersects the surface at a great circle called the Equator. Planes parallel to the plane intersect the surface in circles of constant latitude. The Equator has a latitude of 0°, the North Pole has a latitude of 90° North, the latitude of an arbitrary point is the angle between the equatorial plane and the radius to that point. The latitude, as defined in this way for the sphere, is termed the spherical latitude
7.
Arctic Circle
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The Arctic Circle is the most northerly of the abstract five major circles of latitude as shown on maps of the Earth. The region north of this circle is known as the Arctic, the position of the Arctic Circle is not fixed, as of 7 April 2017, it runs 66°33′46. 6″ north of the Equator. Its latitude depends on the Earths axial tilt, which fluctuates within a margin of 2° over a 40, 000-year period, consequently, the Arctic Circle is currently drifting northwards at a speed of about 15 m per year. The word arctic comes from the Greek word ἀρκτικός and that from the word ἄρκτος, directly on the Arctic Circle these events occur, in principle, exactly once per year, at the June and December solstices, respectively. That is true at sea level, those limits increase with elevation above sea level, tens of thousands of years ago, waves of people migrated from eastern Siberia across the Bering Strait into North America to settle. Much later, in the period, there has been migration into some Arctic areas by Europeans. The largest communities north of the Arctic Circle are situated in Russia and Norway, Murmansk, Norilsk, Tromsø, rovaniemi in Finland is the largest settlement in the immediate vicinity of the Arctic Circle, lying slightly south of the line. In contrast, the largest North American community north of the Arctic Circle, of the Canadian and United States Arctic communities, Barrow, Alaska is the largest settlement with about 4,000 inhabitants. The Arctic Circle is roughly 16,000 kilometres, the area north of the Circle is about 20,000,000 km2 and covers roughly 4% of Earths surface. The Arctic Circle passes through the Arctic Ocean, the Scandinavian Peninsula, North Asia, Northern America, the land within the Arctic Circle is divided among eight countries, Norway, Sweden, Finland, Russia, the United States, Canada, Denmark, and Iceland. In the interior, summers can be warm, while winters are extremely cold
8.
Antarctic Circle
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The Antarctic Circle is the most southerly of the five major circles of latitude that mark maps of the Earth. The region south of this circle is known as the Antarctic, the position of the Antarctic Circle is not fixed, as of 9 April 2017, it runs 66°33′46. 6″ south of the Equator. Its latitude depends on the Earths axial tilt, which fluctuates within a margin of 2° over a 40, 000-year period, consequently, the Antarctic Circle is currently drifting southwards at a speed of about 15 m per year. Directly on the Antarctic Circle these events occur, in principle, exactly once per year, at the December and June solstices, respectively. That is true at sea level, those limits increase with elevation above sea level, in previous centuries some semi-permanent whaling stations were established on the continent, and some whalers would live there for a year or more. At least three children have been born in Antarctica, albeit in stations north of the Antarctic Circle, the Antarctic Circle is roughly 17,662 kilometres long. The area south of the Circle is about 20,000,000 km2, the continent of Antarctica covers much of the area within the Antarctic Circle
9.
Elevation
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GIS or geographic information system is a computer system that allows for visualizing, manipulating, capturing, and storage of data with associated attributes. GIS offers better understanding of patterns and relationships of the landscape at different scales, tools inside the GIS allow for manipulation of data for spatial analysis or cartography. A topographical map is the type of map used to depict elevation. In a Geographic Information System, digital models are commonly used to represent the surface of a place. Digital terrain models are another way to represent terrain in GIS, USGS is developing a 3D Elevation Program to keep up with growing needs for high quality topographic data. 3DEP is a collection of enhanced elevation data in the form of high quality LiDAR data over the conterminous United States, Hawaii, there are three bare earth DEM layers in 3DEP which are nationally seamless at the resolution of 1/3,1, and 2 arcseconds. This map is derived from GTOPO30 data that describes the elevation of Earths terrain at intervals of 30 arcseconds and it uses color and shading instead of contour lines to indicate elevation. Hypsography is the study of the distribution of elevations on the surface of the Earth, the term originates from the Greek word ὕψος hypsos meaning height. Most often it is used only in reference to elevation of land, related to the term hypsometry, the measurement of these elevations of a planets solid surface are taken relative to mean datum, except for Earth which is taken relative to the sea level. In the troposphere, temperatures decrease with altitude and this lapse rate is approximately 6.5 °C/km. S
10.
Arctic Ocean
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The Arctic Ocean is the smallest and shallowest of the worlds five major oceans. Alternatively, the Arctic Ocean can be seen as the northernmost part of the all-encompassing World Ocean, located mostly in the Arctic north polar region in the middle of the Northern Hemisphere, the Arctic Ocean is almost completely surrounded by Eurasia and North America. It is partly covered by sea ice throughout the year and almost completely in winter, the summer shrinking of the ice has been quoted at 50%. The US National Snow and Ice Data Center uses satellite data to provide a record of Arctic sea ice cover. The Arctic may become ice free for the first time in human history within a few years or by 2040, for much of European history, the north polar regions remained largely unexplored and their geography conjectural. He was probably describing loose sea ice known today as growlers or bergy bits, his Thule was probably Norway, early cartographers were unsure whether to draw the region around the North Pole as land or water. The makers of navigational charts, more conservative than some of the more fanciful cartographers, tended to leave the region blank and this lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an Open Polar Sea was persistent, john Barrow, longtime Second Secretary of the British Admiralty, promoted exploration of the region from 1818 to 1845 in search of this. In the United States in the 1850s and 1860s, the explorers Elisha Kane, even quite late in the century, the eminent authority Matthew Fontaine Maury included a description of the Open Polar Sea in his textbook The Physical Geography of the Sea. Nevertheless, as all the explorers who travelled closer and closer to the reported, the polar ice cap is quite thick. Fridtjof Nansen was the first to make a crossing of the Arctic Ocean. The first surface crossing of the ocean was led by Wally Herbert in 1969, in a dog sled expedition from Alaska to Svalbard, with air support. The first nautical transit of the pole was made in 1958 by the submarine USS Nautilus. Since 1937, Soviet and Russian manned drifting ice stations have extensively monitored the Arctic Ocean, scientific settlements were established on the drift ice and carried thousands of kilometres by ice floes. In World War II, the European region of the Arctic Ocean was heavily contested, the Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2, almost the size of Antarctica. The coastline is 45,390 km long and it is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands. It is connected to the Pacific Ocean by the Bering Strait and to the Atlantic Ocean through the Greenland Sea, countries bordering the Arctic Ocean are, Russia, Norway, Iceland, Greenland, Canada and the United States. There are several ports and harbours around the Arctic Ocean In Alaska, in Canada, ships may anchor at Churchill in Manitoba, Nanisivik in Nunavut, Tuktoyaktuk or Inuvik in the Northwest territories
11.
Sediment
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For sediment in beverages, see dregs. For example, sand and silt can be carried in suspension in water and on reaching the sea be deposited by sedimentation. Sediments are most often transported by water, but also wind, beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of transport and deposition. Glacial moraine deposits and till are ice-transported sediments, sediment can be classified based on its grain size and/or its composition. Sediment size is measured on a log base 2 scale, called the Phi scale, composition of sediment can be measured in terms of, parent rock lithology mineral composition chemical make-up. This leads to an ambiguity in which clay can be used as both a size-range and a composition, sediment is transported based on the strength of the flow that carries it and its own size, volume, density, and shape. Stronger flows will increase the lift and drag on the particle, causing it to rise, rivers and streams carry sediment in their flows. This sediment can be in a variety of locations within the flow and these relationships are shown in the following table for the Rouse number, which is a ratio of sediment fall velocity to upwards velocity. If the upwards velocity is less than the settling velocity, but still high enough for the sediment to move, it will move along the bed as bed load by rolling, sliding. If the upwards velocity is higher than the velocity, the sediment will be transported high in the flow as wash load. As there are generally a range of different particle sizes in the flow, sediment motion can create self-organized structures such as ripples, dunes, antidunes on the river or stream bed. These bedforms are often preserved in rocks and can be used to estimate the direction. Overland flow can erode soil particles and transport them downslope, the erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions. If the initial impact of rain droplets dislodges soil, the phenomenon is called rainsplash erosion, if overland flow is directly responsible for sediment entrainment but does not form gullies, it is called sheet erosion. If the flow and the substrate permit channelization, gullies may form, glaciers carry a wide range of sediment sizes, and deposit it in moraines. The overall balance between sediment in transport and sediment being deposited on the bed is given by the Exner equation and this expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow. This can be localized, and simply due to obstacles, examples are scour holes behind boulders, where flow accelerates
12.
Tibetan Plateau
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It stretches approximately 1,000 kilometres north to south and 2,500 kilometres east to west. Sometimes termed the Third Pole, the Tibetan Plateau contains the headwaters of the basins of most of the streams in surrounding regions. Its tens of thousands of glaciers and other geographical and ecological features serve as a water tower storing water, the impact of global warming on the Tibetan Plateau is of intense scientific interest. The Tibetan Plateau is surrounded by mountain ranges. In the west the curve of the rugged Karakoram range of northern Kashmir embraces the plateau, the Indus River originates in the western Tibetan Plateau in the vicinity of Lake Mansarovar. The Tibetan Plateau is bounded in the north by an escarpment where the altitude drops from around 5,000 metres to 1,500 metres over a horizontal distance of less than 150 kilometres. Along the escarpment is a range of mountains, in the west the Kunlun Mountains separate the plateau from the Tarim Basin. About halfway across the Tarim the bounding range becomes the Altyn-Tagh, in the V formed by this split is the western part of the Qaidam Basin. The Altyn-Tagh ends near the Dangjin pass on the Dunhuang-Golmud road, to the west are short ranges called the Danghe, Yema, Shule, and Tulai Nanshans. The easternmost range is the Qilian Mountains, the line of mountains continues east of the plateau as the Qin Mountains which separate the Ordos Region from Sichuan. North of the runs the Gansu or Hexi Corridor which was the main silk-road route from China proper to the West. The plateau is an arid steppe interspersed with mountain ranges. Annual precipitation ranges from 100 to 300 millimetres and falls mainly as hail, the southern and eastern edges of the steppe have grasslands which can sustainably support populations of nomadic herdsmen, although frost occurs for six months of the year. Permafrost occurs over parts of the plateau. Proceeding to the north and northwest, the plateau becomes progressively higher, colder and drier, here the average altitude exceeds 5,000 metres and winter temperatures can drop to −40 °C. The geological history of the Tibetan Plateau is closely related to that of the Himalayan mountain range, the Himalayas are among the youngest mountain ranges on the planet and consist mostly of uplifted sedimentary and metamorphic rock. Their formation is a result of a collision or orogeny along the convergent boundary between the Indo-Australian Plate and the Eurasian Plate. The collision began in the Upper Cretaceous period about 70 million years ago, since these sediments were light, they crumpled into mountain ranges rather than sinking to the floor
13.
Active layer
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In environments containing permafrost, the active layer is the top layer of soil that thaws during the summer and freezes again during the autumn. This means that, over years, the influence of cooling in winter. If the winter temperature is below the point of water. This frost front is the boundary between frozen and unfrozen soil, and with the coming of spring and summer, the soil is thawed, always from the top down. If the heating during summer exceeds the cooling during winter, the soil will be completely thawed during the summer and there will be no permafrost. This occurs when the annual temperature is above 0°C. When there is not sufficient heat to thaw the frozen soil completely, liquid water cannot flow below the active layer, with the result that permafrost environments tend to be very poorly drained and boggy. The thickness of the layer is the average annual thaw depth in permafrost areas. Thus, the determinant of active layer thickness is the maximum temperature attained during the summer. This is because the material allows for much greater conductivity of heat down into the soil. This is important because roots of plants cannot penetrate beyond the active layer and are restricted by its thickness, thus, in a continuous permafrost environment plants must have shallow roots, which restricts tree growth to specialised species such as Larix. In areas of discontinuous permafrost, most conifers are able to grow easily, cryoturbation is the dominant force operating in the active layer, and tends to make it generally uniform in composition throughout. However, variation in the composition of soils due to differences in parent rock are very marked in permafrost regions due to the low rate of weathering in the cold climate. The slow rate of decomposition of organic material means gelisols are very important as a sink for carbon dioxide
14.
Plant
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Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. The term is generally limited to the green plants, which form an unranked clade Viridiplantae. This includes the plants, conifers and other gymnosperms, ferns, clubmosses, hornworts, liverworts, mosses and the green algae. Green plants have cell walls containing cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts and their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic and have lost the ability to produce amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although reproduction is also common. There are about 300–315 thousand species of plants, of which the great majority, green plants provide most of the worlds molecular oxygen and are the basis of most of Earths ecologies, especially on land. Plants that produce grains, fruits and vegetables form humankinds basic foodstuffs, Plants play many roles in culture. They are used as ornaments and, until recently and in variety, they have served as the source of most medicines. The scientific study of plants is known as botany, a branch of biology, Plants are one of the two groups into which all living things were traditionally divided, the other is animals. The division goes back at least as far as Aristotle, who distinguished between plants, which generally do not move, and animals, which often are mobile to catch their food. Much later, when Linnaeus created the basis of the system of scientific classification. Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, however, these organisms are still often considered plants, particularly in popular contexts. When the name Plantae or plant is applied to a group of organisms or taxon. The evolutionary history of plants is not yet settled. Those which have been called plants are in bold, the way in which the groups of green algae are combined and named varies considerably between authors. Algae comprise several different groups of organisms which produce energy through photosynthesis, most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble land plants, but are classified among the brown, red and green algae. Each of these groups also includes various microscopic and single-celled organisms
15.
Metre
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The metre or meter, is the base unit of length in the International System of Units. The metre is defined as the length of the path travelled by light in a vacuum in 1/299792458 seconds, the metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole. In 1799, it was redefined in terms of a metre bar. In 1960, the metre was redefined in terms of a number of wavelengths of a certain emission line of krypton-86. In 1983, the current definition was adopted, the imperial inch is defined as 0.0254 metres. One metre is about 3 3⁄8 inches longer than a yard, Metre is the standard spelling of the metric unit for length in nearly all English-speaking nations except the United States and the Philippines, which use meter. Measuring devices are spelled -meter in all variants of English, the suffix -meter has the same Greek origin as the unit of length. This range of uses is found in Latin, French, English. Thus calls for measurement and moderation. In 1668 the English cleric and philosopher John Wilkins proposed in an essay a decimal-based unit of length, as a result of the French Revolution, the French Academy of Sciences charged a commission with determining a single scale for all measures. In 1668, Wilkins proposed using Christopher Wrens suggestion of defining the metre using a pendulum with a length which produced a half-period of one second, christiaan Huygens had observed that length to be 38 Rijnland inches or 39.26 English inches. This is the equivalent of what is now known to be 997 mm, no official action was taken regarding this suggestion. In the 18th century, there were two approaches to the definition of the unit of length. One favoured Wilkins approach, to define the metre in terms of the length of a pendulum which produced a half-period of one second. The other approach was to define the metre as one ten-millionth of the length of a quadrant along the Earths meridian, that is, the distance from the Equator to the North Pole. This means that the quadrant would have defined as exactly 10000000 metres at that time. To establish a universally accepted foundation for the definition of the metre, more measurements of this meridian were needed. This portion of the meridian, assumed to be the length as the Paris meridian, was to serve as the basis for the length of the half meridian connecting the North Pole with the Equator
16.
Foot (unit)
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The foot is a unit of length in the imperial and US customary systems of measurement. Since 1959, both units have been defined by international agreement as equivalent to 0.3048 meters exactly, in both systems, the foot comprises 12 inches and three feet compose a yard. Historically the foot was a part of local systems of units, including the Greek, Roman, Chinese, French. It varied in length from country to country, from city to city and its length was usually between 250 mm and 335 mm and was generally, but not always, subdivided into 12 inches or 16 digits. The United States is the industrialized nation that uses the international foot and the survey foot in preference to the meter in its commercial, engineering. The foot is legally recognized in the United Kingdom, road signs must use imperial units, the measurement of altitude in international aviation is one of the few areas where the foot is widely used outside the English-speaking world. The length of the international foot corresponds to a foot with shoe size of 13,14,15.5 or 46. Historically the human body has been used to provide the basis for units of length. The foot of a male is typically about 15. 3% of his height, giving a person of 160 cm a foot of 245 mm. These figures are less than the used in most cities over time. Archeologists believe that the Egyptians, Ancient Indians and Mesopotamians preferred the cubit while the Romans, under the Harappan linear measures, Indus cities during the Bronze Age used a foot of 13.2 inches and a cubit of 20.8 inches. The Egyptian equivalent of the measure of four palms or 16 digits—was known as the djeser and has been reconstructed as about 30 cm. The Greek foot had a length of 1⁄600 of a stadion, one stadion being about 181.2 m, the standard Roman foot was normally about 295.7 mm, but in the provinces, the pes Drusianus was used, with a length of about 334 mm. Originally both the Greeks and the Romans subdivided the foot into 16 digits, but in later years, after the fall of the Roman Empire, some Roman traditions were continued but others fell into disuse. In AD790 Charlemagne attempted to reform the units of measure in his domains and his units of length were based on the toise and in particular the toise de lÉcritoire, the distance between the fingertips of the outstretched arms of a man. The toise has 6 pieds each of 326.6 mm, at the same time, monastic buildings used the Carolingian foot of 340 mm. The procedure for verification of the foot as described in the 16th century by Jacob Koebel in his book Geometrei, the measures of Iron Age Britain are uncertain and proposed reconstructions such as the Megalithic Yard are controversial. Later Welsh legend credited Dyfnwal Moelmud with the establishment of their units, the Belgic or North German foot of 335 mm was introduced to England either by the Belgic Celts during their invasions prior to the Romans or by the Anglo-Saxons in the 5th & 6th century
17.
Carbon
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Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
18.
Peat
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Peat, also called turf, is an accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem is the most efficient carbon sink on the planet because peatland plants capture the CO2 which is released from the peat. Sphagnum moss is one of the most common components in peat, soils that contain mostly peat are known as histosols. Peat forms in wetland conditions, where flooding obstructs flows of oxygen from the atmosphere, Peatlands, particularly bogs, are the most important source of peat. That said, other less common types, including fens, pocosins. Landscapes covered in peat are home to specific kinds of plants including Sphagnum moss, ericaceous shrubs, because organic matter accumulates over thousands of years, peat deposits also provide records of past vegetation and climates stored in plant remains like pollen. This allows humans to reconstruct past environments and study changes in land use. Peat is harvested as an important source of fuel in certain parts of the world, by volume, there are about 4 trillion cubic metres of peat in the world, covering a total of around 2% of the global land area, containing about 8 billion terajoules of energy. Over time, the formation of peat is often the first step in the formation of other fossil fuels such as coal. This is also the commonly used in the peat industry. At 106 g CO2/MJ, the carbon dioxide emission intensity of peat is higher than that of coal and natural gas, lastly, peat fires have been responsible for large public health disasters including the 1997 Southeast Asian haze. Peat forms when plant material does not fully decay in acidic and anaerobic conditions and it is composed mainly of wetland vegetation, principally bog plants including mosses, sedges, and shrubs. As it accumulates, the peat holds water and this slowly creates wetter conditions that allow the area of wetland to expand. Peatland features can include ponds, ridges, and raised bogs, most modern peat bogs formed 12,000 years ago in high latitudes after the glaciers retreated at the end of the last ice age. Peat usually accumulates slowly at the rate of about a millimetre per year, using Carbon-dating, scientists found that Peat in peatlands started forming 360 million years ago based on it currently containing 550 Gt of carbon. Peat material is either fibric, hemic, or sapric, fibric peats are the least decomposed and consist of intact fiber. Hemic peats are partially decomposed and sapric are the most decomposed, Phragmites peat is one composed of reed grass, Phragmites australis, and other grasses. It is denser than other types of peat
19.
Jackhammer
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A jackhammer is a pneumatic or electro-mechanical tool that combines a hammer directly with a chisel. It was invented by William Mcreavy, who sold the patent to Charles Brady King. Hand-held jackhammers are generally powered by compressed air, but some are powered by electric motors. Larger jackhammers, such as rig mounted hammers used on machinery, are usually hydraulically powered. They are typically used to break up rock, pavement, a jackhammer operates by driving an internal hammer up and down. The hammer is first driven down to strike the back and then back up to return the hammer to the position to repeat the cycle. The effectiveness of the jackhammer is dependent on how much force is applied to the tool and it is generally used like a hammer to break the hard surface or rock in construction works and it is not consider under earth moving equipment, along with its accessories. In British English, electromechanical versions are known as Kangos. Pneumatic drills were developed in response to the needs of mining, quarrying, excavating, in 1838 Isaac Singer invented a steam driven drill. A pneumatic drill was proposed by a C, the first percussion drill was made in 1848 and patented in 1849 by Jonathan J. Couch of Philadelphia, Pennsylvania. In this drill, the drill bit passed through the piston of a steam engine, the piston snagged the drill bit and hurled it against the rock face. In 1849, Couchs assistant, Joseph W. Fowle, filed a patent caveat for a drill of his own design. In Fowle’s drill, the bit was connected directly to the piston in the steam cylinder, specifically. The drill also had a mechanism for turning the drill bit around its axis between strokes and for advancing the drill as the hole deepened, by 1850 or 1851, Fowle was using compressed air to drive his drill, making it the first true pneumatic drill. By contrast, compressed air could be conveyed over distances without loss of its energy. The need for a rock drill was obvious and this sparked research on pneumatic rock drills in Europe. A Frenchman, Cavé, designed, and in 1851 patented, a drill that used compressed air. In 1854, in England, Thomas Bartlett made and then patented a rock drill whose drill bit was connected directly to the piston of a steam engine, in 1855 Bartlett demonstrated his drill, powered by compressed air, to officials of the Mt. Fréjus tunnel project
20.
Alaska
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Alaska is a U. S. state located in the northwest extremity of North America. To the north are the Chukchi and Beaufort seas–the southern parts of the Arctic Ocean, the Pacific Ocean lies to the south and southwest. Alaska is the largest state in the United States by area, the 3rd least populous, approximately half of Alaskas residents live within the Anchorage metropolitan area. Alaskas economy is dominated by the fishing, natural gas, military bases and tourism are also a significant part of the economy. The United States purchased Alaska from the Russian Empire on March 30,1867, the area went through several administrative changes before becoming organized as a territory on May 11,1912. It was admitted as the 49th state of the U. S. on January 3,1959, the name Alaska was introduced in the Russian colonial period when it was used to refer to the peninsula. It was derived from an Aleut, or Unangam idiom, which refers to the mainland of Alaska. Literally, it means object to which the action of the sea is directed, Alaska is the northernmost and westernmost state in the United States and has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere. Alaska is the only non-contiguous U. S. state on continental North America and it is technically part of the continental U. S. but is sometimes not included in colloquial use, Alaska is not part of the contiguous U. S. often called the Lower 48. The capital city, Juneau, is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system. Alaskas territorial waters touch Russias territorial waters in the Bering Strait, as the Russian Big Diomede Island, Alaska has a longer coastline than all the other U. S. states combined. Alaska is the largest state in the United States by total area at 663,268 square miles, over twice the size of Texas, Alaska is larger than all but 18 sovereign countries. Counting territorial waters, Alaska is larger than the area of the next three largest states, Texas, California, and Montana. It is also larger than the area of the 22 smallest U. S. states. Also referred to as the Panhandle or Inside Passage, this is the region of Alaska closest to the rest of the United States, as such, this was where most of the initial non-indigenous settlement occurred in the years following the Alaska Purchase. The region is dominated by the Alexander Archipelago as well as the Tongass National Forest and it contains the state capital Juneau, the former capital Sitka, and Ketchikan, at one time Alaskas largest city. The Alaska Marine Highway provides a vital transportation link throughout the area. The Interior is the largest region of Alaska, much of it is uninhabited wilderness, Fairbanks is the only large city in the region
21.
Climate
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Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
22.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
23.
Ural Mountains
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The mountain range forms part of the conventional boundary between the continents of Europe and Asia. Vaygach Island and the islands of Novaya Zemlya form a continuation of the chain to the north into the Arctic Ocean. The mountains lie within the Ural geographical region and significantly overlap with the Ural Federal District and they have rich resources, including metal ores, coal, precious and semi-precious stones. Since the 18th century the mountains have contributed significantly to the sector of the Russian economy. As attested by Sigismund von Herberstein, in the 16th century Russians called the range by a variety of names derived from the Russian words for rock and it might have been a borrowing from either Turkic stone belt, or Ob-Ugric. From the 13th century, in Bashkortostan there has been a legend about a hero named Ural and he sacrificed his life for the sake of his people and they poured a stone pile over his grave, which later turned into the Ural Mountains. Possibilities include Bashkir үр elevation, upland or Mansi ур ала mountain peak, top of the mountain, tatischev believes that this oronym is set to belt and associates it with the Turkic verb oralu- gird. Dobrodomov suggests a transition from Aral to Ural explained on the basis of ancient Bulgar-Chuvash dialects, hawks believes that the name goes back to the Bashkir folklore Ural-Batyr. Shumilov suggested a Mongolian origin, Khural Uul, that is, the Evenk geographical term era mountain has also been theorized. Finno-Ugrist scholars consider Ural deriving from the Mansi word urr meaning a mountain, turkologists, on the other hand, have achieved majority support for their assertion that ural in Tatar means a belt, and recall that an earlier name for the range was stone belt. During the next few centuries Novgorodians engaged in fur trading with the population and collected tribute from Yugra and Great Perm. The rivers Chusovaya and Belaya were first mentioned in the chronicles of 1396 and 1468, in 1430 the town of Solikamsk was founded on the Kama at the foothills of the Ural, where salt was produced in open pans. Ivan III of Moscow captured Perm, Pechora and Yugra from the declining Novgorod Republic in 1472, with the excursions of 1483 and 1499–1500 across the Ural Moscow managed to subjugate Yugra completely. The Middle and Southern Ural were still largely unavailable and unknown to the Russian or Western European geographers, the Stroganovs land provided the staging ground for Yermaks incursion into Siberia. Yermak crossed the Ural from the Chusovaya to the Tagil around 1581, in 1597 Babinovs road was built across the Ural from Solikamsk to the valley of the Tura, where the town of Verkhoturye was founded in 1598. Customs was established in Verkhoturye shortly thereafter and the road was made the legal connection between European Russia and Siberia for a long time. In 1648 the town of Kungur was founded at the foothills of the Middle Ural. During the 17th century the first deposits of iron and copper ores, mica, gemstones, iron and copper smelting works emerged
24.
Glacier
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A glacier is a persistent body of dense ice that is constantly moving under its own weight, it forms where the accumulation of snow exceeds its ablation over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs and they also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice, between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earths land surface, continental glaciers cover nearly 13,000,000 km2 or about 98 percent of Antarcticas 13,200,000 km2, with an average thickness of 2,100 m. Greenland and Patagonia also have huge expanses of continental glaciers, Glacial ice is the largest reservoir of fresh water on Earth. Within high altitude and Antarctic environments, the temperature difference is often not sufficient to release meltwater. A large piece of compressed ice, or a glacier, appears blue as large quantities of water appear blue and this is because water molecules absorb other colors more efficiently than blue. The other reason for the color of glaciers is the lack of air bubbles. Air bubbles, which give a color to ice, are squeezed out by pressure increasing the density of the created ice. The word Glaceon is a loanword from French and goes back, via Franco-Provençal, to the Vulgar Latin glaciārium, derived from the Late Latin glacia, the processes and features caused by or related to glaciers are referred to as glacial. The process of establishment, growth and flow is called glaciation. The corresponding area of study is called glaciology, Glaciers are important components of the global cryosphere. Glaciers are categorized by their morphology, thermal characteristics, and behavior, cirque glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier, a large body of glacial ice astride a mountain, mountain range, or volcano is termed an ice cap or ice field. Ice caps have a less than 50,000 km2 by definition. Glacial bodies larger than 50,000 km2 are called ice sheets or continental glaciers, 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. They contain vast quantities of water, enough that if both melted, global sea levels would rise by over 70 m
25.
Pressure melting point
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The pressure melting point is the temperature at which ice melts at a given pressure. With increasing pressure above 10 MPa, the melting point decreases to a minimum of −21.9 °C at 209.9 MPa. Thereafter, the melting point rises rapidly with pressure, passing back through 0 °C at 632.4 MPa. Glaciers are subject to heat flux from below and atmospheric warming or cooling from above. As the pressure increases with depth in a glacier from the weight of the ice above, the level where ice can start melting is where the pressure melting point equals the actual temperature. In static equilibrium conditions, this would be the highest level where water can exist in a glacier and it would also be the level of the base of an ice shelf, or the ice-water interface of a subglacial lake
26.
Geothermal gradient
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Geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earths interior. Away from tectonic plate boundaries, it is about 25 °C per km of depth near the surface in most of the world, strictly speaking, geo-thermal necessarily refers to the Earth but the concept may be applied to other planets. A line tracing the gradient through the body is called a geotherm on Earth. On the Moon it is called a selenotherm, the Earths internal heat comes from a combination of residual heat from planetary accretion, heat produced through radioactive decay, and possibly heat from other sources. The major heat-producing isotopes in the Earth are potassium-40, uranium-238, uranium-235, at the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa. Temperature within the Earth increases with depth, the heat content of the Earth is 1031 joules. Much of the heat is created by decay of radioactive elements. An estimated 45 to 90 percent of the heat escaping from the Earth originates from decay of elements mainly located in the mantle. Heat of impact and compression released during the formation of the Earth by accretion of in-falling meteorites. Heat released as abundant heavy metals descended to the Earths core, latent heat released as the liquid outer core crystallizes at the inner core boundary. Heat may be generated by tidal force on the Earth as it rotates, since rock cannot flow as readily as water it compresses and distorts, in Earths continental crust, the decay of natural radioactive isotopes has had significant involvement in the origin of geothermal heat. The continental crust is abundant in lower density minerals but also contains significant concentrations of heavier lithophilic minerals such as uranium, because of this, it holds the largest global reservoir of radioactive elements found in the Earth. Especially in layers closer to Earths surface, naturally occurring isotopes are enriched in the granite and these high levels of radioactive elements are largely excluded from the Earths mantle due to their inability to substitute in mantle minerals and consequent enrichment in partial melts. The mantle is made up of high density minerals with high contents of atoms that have relatively small atomic radii such as magnesium, titanium. Heat flows constantly from its sources within the Earth to the surface, total heat loss from the Earth is estimated at 44.2 TW. Mean heat flow is 65 mW/m2 over continental crust and 101 mW/m2 over oceanic crust and this is 0.087 watt/square meter on average, but is much more concentrated in areas where thermal energy is transported toward the crust by convection such as along mid-ocean ridges and mantle plumes. The Earths crust effectively acts as an insulating blanket which must be pierced by fluid conduits in order to release the heat underneath. More of the heat in the Earth is lost through plate tectonics, the final major mode of heat loss is by conduction through the lithosphere, the majority of which occurs in the oceans due to the crust there being much thinner and younger than under the continents
27.
Aspect (geography)
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In physical geology, aspect is the compass direction that a slope faces. For example, a slope on the edge of the Rockies toward the Great Plains is described as having an easterly aspect. A slope which falls down to a valley on its western side. The direction a slope faces can affect the physical and biotic features of the slope, the term aspect can also be used to describe the shape or alignment of a coastline. Here, the aspect is the direction which the coastline is facing towards the sea, for example, a coastline with sea to the northeast has a northeasterly aspect. Aspect can have an influence on temperature. This is because of the angle of the sun in the northern and southern hemispheres which is less than 90 degrees or directly overhead. 5° at 40° north on December 22, the aspect of a slope can make very significant influences on its local climate. For example, because the rays are in the west at the hottest time of day in the afternoon. This can have effects on altitudinal and polar limits of tree growth. In Australia, for example, remnants of rainforest are almost always found on east-facing slopes which are protected from dry westerly wind, similarly, in the northern hemisphere a south-facing slope will therefore generally be warmer and dryer due to higher levels of evapotranspiration than a north-facing slope. This can be seen in the Swiss Alps, where farming is more extensive on south-facing than on north-facing slopes. In the Himalayas, this effect can be seen to a degree, with south-facing slopes being warm, wet and forested. In some locales there are patterns of soil differences related to differences in aspect, aspect similarly influence seasonal soil biological processes that are temperature dependent. Particulate laden winds often blow from a prevailing direction near solar early afternoon, the summer dryness of the Coromandel Coast due to the southerly monsoon flowing parallel to the coast. Its wetness during the northeast monsoon is similarly explained, the anomalous late autumn rainy seasons of central Vietnam and the coastal zone of northeastern Brazil for the same reason as above. The unusual dryness of Port Moresby compared to the rest of New Guinea is because the National Capital District lies parallel to the winds which have a drying effect. In Gulf Province and Lae, which receives their full force, rainfall during winter is exceedingly heavy, with rainfall. The relative dryness of the Queensland coast has the same cause as with Port Moresby
28.
Siberia
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Siberia is an extensive geographical region, and by the broadest definition is also known as North Asia. Siberia has historically been a part of Russia since the 17th century, the territory of Siberia extends eastwards from the Ural Mountains to the watershed between the Pacific and Arctic drainage basins. It stretches southwards from the Arctic Ocean to the hills of north-central Kazakhstan and to the borders of Mongolia. With an area of 13.1 million square kilometres, Siberia accounts for 77% of Russias land area and this is equivalent to an average population density of about 3 inhabitants per square kilometre, making Siberia one of the most sparsely populated regions on Earth. If it were a country by itself, it would still be the largest country in area, the origin of the name is unknown. Some sources say that Siberia originates from the Siberian Tatar word for sleeping land, another account sees the name as the ancient tribal ethnonym of the Sirtya, a folk, which spoke a language that later evolved into the Ugric languages. This ethnic group was assimilated to the Siberian Tatar people. The modern usage of the name was recorded in the Russian language after the Empires conquest of the Siberian Khanate, a further variant claims that the region was named after the Xibe people. The Polish historian Chycliczkowski has proposed that the name derives from the word for north. He said that the neighbouring Chinese, Arabs and Mongolians would not have known Russian and he suggests that the name is a combination of two words, su and bir. The region is of significance, as it contains bodies of prehistoric animals from the Pleistocene Epoch. Specimens of Goldfuss cave lion cubs, Yuka and another woolly mammoth from Oymyakon, a rhinoceros from the Kolyma River. The Siberian Traps were formed by one of the largest known volcanic events of the last 500 million years of Earths geological history. They continued for a million years and are considered a cause of the Great Dying about 250 million years ago. At least three species of human lived in Southern Siberia around 40,000 years ago, H. sapiens, H. neanderthalensis, the last was determined in 2010, by DNA evidence, to be a new species. Siberia was inhabited by different groups of such as the Enets, the Nenets, the Huns, the Scythians. The Khan of Sibir in the vicinity of modern Tobolsk was known as a prominent figure who endorsed Kubrat as Khagan of Old Great Bulgaria in 630, the Mongols conquered a large part of this area early in the 13th century. With the breakup of the Golden Horde, the autonomous Khanate of Sibir was established in the late 15th century, turkic-speaking Yakut migrated north from the Lake Baikal region under pressure from the Mongol tribes during the 13th to 15th century
29.
Khangai Mountains
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The Khangai Mountains are a mountain range in central Mongolia, some 400 kilometres west of Ulaanbaatar. Khangai has become a generally used term by Mongolians to describe the entire lush forest-steppe area to the north as opposed to the southern desert, the intermediary steppe area is called Kheer or Tal. The word Khangai is composed of the verb khanga- which means provide, supply with necessities, the word Khan is also a possible root, probably even related to the verb khanga-. Therefore, Khangai is usually interpreted as provident lord, munificent king, the ancient name denotes the sacredness of the mountain and the special place it holds in the hearts of those who depend on it. A similar Mongolian word for sacred mountains is Khairkhan which means loving king and its forbidden to say the name of a Khairkhan when the mountain is in view. If the mountain is in view, it should simply be called Khairkhan and this strict custom applies in all regions of Mongolia. Any mountain or hill that is pleasing to the sight or in any other way pleasant is praised with the words that is indeed a special Khairkhan or what a majestic Khairkhan, two provinces of Mongolia are named after the Khangai mountains, Arkhangai and Ovorkhangai. The mild climate area where the two meet is known as the cradle of Mongolian and nomadic civilization. The plains at the foot of the eastern Khangai host the Orkhon Valley World Heritage Site, the Xiongnu capital Luut Khot, the Xianbei capital Ordo and the Rouran capital Moomt are said to have been located there. Later empires also established their capitals there, for example the Uyghur Empire built their capital Ordu-Baliq in the region. The tallest mountain is the Otgontenger, the height of which is given as 3,905,4,021 and it is one of the four paramount sacred mountains of Mongolia. Suvraga Khairkhan is another sacred mountain to the east of Tsetserleg, taryatu-Chulutu is an extinct volcanic field on the northern slopes of the Khangai Mountains. The mountains feed the rivers Orkhon, Selenge, Ider, Zavkhan, in the west the Khangai mountains transition into the Great Lakes Depression. The Khangai mountain region is known for its mild microclimates in certain areas, winters there are not as harsh as in other parts of the country. It is likely that even the highest mountain tops are some 5°C warmer than the sub-Khangai basins
30.
Altai Mountains
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The Altai Mountains are a mountain range in Central and East Asia, where Russia, China, Mongolia, and Kazakhstan come together, and are where the rivers Irtysh and Ob have their headwaters. The name Altai means Gold Mountain in Mongolian, alt and tai and also in its Chinese name, in Turkic languages altin means gold and dag means mountain. The proposed Altaic language family takes its name from this mountain range and their mean elevation is 1,500 to 1,750 m. The snow-line runs at 2,000 m on the side and at 2,400 m on the southern. Mountain passes across the range are few and difficult, the chief being the Ulan-daban at 2,827 m, and this region is studded with large lakes, e. g. The north western and northern slopes of the Sailughem Mountains are extremely steep, on this side lies the highest summit of the range, the double-headed Belukha, whose summits reach 4,506 and 4,440 m respectively, and give origin to several glaciers. Altaians call it Kadyn Bazhy, but is also called Uch-Sumer, the second highest peak of the range is in Mongolian part named Khüiten Peak. This massive peak reaches 4374 m, numerous spurs, striking in all directions from the Sailughem mountains, fill up the space between that range and the lowlands of Tomsk. The Katun and the Biya together form the Ob, the next valley is that of the Charysh, which has the Korgon and Tigeretsk Alps on one side and the Talitsk and Bashalatsk Alps on the other. The Altai, seen from this valley, presents the most romantic scenes, including the small but deep Kolyvan lake, farther west the valleys of the Uba, the Ulba and the Bukhtarma open south-westwards towards the Irtysh. The lower part of the first, like the valley of the Charysh, is thickly populated, in the valley of the Ulba is the Riddersk mine, at the foot of the Ivanovsk Peak. Its upper parts abound in glaciers, the best known of which is the Berel, on the northern side of the range which separates the upper Bukhtarma from the upper Katun is the Katun glacier, which after two ice-falls widens out to 700 to 900 metres. From a grotto in this glacier bursts tumultuously the Katun river, the high valleys farther north, on the same western face of the Sailughem range, are but little known, their only visitors being Kyrgyz shepherds. Those of Bashkaus, Chulyshman, and Chulcha, all three leading to the lake of Teletskoye, are inhabited by Telengit people. The shores of the lake rise almost sheer to over 1,800 m, from this lake issues the Biya, which joins the Katun at Biysk, and then meanders through the prairies of the north-west of the Altai. Farther north the Altai highlands are continued in the Kuznetsk district, which has a different geological aspect. But the Abakan River, which rises on the shoulder of the Sayan mountains. East of 94° E the range is continued by a series of mountain chains
31.
Brooks Range
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The Brooks Range is a mountain range in far northern North America stretching some 700 miles from west to east across northern Alaska into Canadas Yukon Territory. Reaching a peak elevation of 8,976 feet on Mount Isto, while the range is mostly uninhabited, the Dalton Highway and Trans-Alaska Pipeline System run through the Atigun Pass on their way to the oil fields at Prudhoe Bay on Alaskas North Slope. The Alaska Native villages of Anaktuvuk and Arctic Village, as well as the small communities of Coldfoot, Wiseman, Bettles. In the far west, near the Wulik River in the De Long Mountains is the Red Dog mine, the range was named by the United States Board on Geographic Names in 1925 after Alfred Hulse Brooks, chief USGS geologist for Alaska from 1903 to 1924. Mount Isto 8,975.1 ft Mount Hubley 8,914 ft Mount Chamberlin 8,898, the range roughly delineates the summer position of the Arctic front. It represents the extent of the tree line, with little beyond isolated Balsam poplar stands occurring north of the continental drainage divide. Trembling aspen and white also occur north of the Brooks Range. Southern slopes have some cover of Black Spruce, Picea mariana, as one of the most remote and least-disturbed wildernesses of North America, the mountains are home to Dall sheep, grizzly bears, and caribou. In Alaska, the 490,000 animal strong Western Arctic Caribou herd traverses the Brooks Range in its annual migration, the migration path of the Porcupine Caribou Herd is the longest of any terrestrial mammal on earth. Because it is composed of ancient seabed, the Brooks Range contains ancient marine. In addition to the fossils shown at left, trilobites. While other Alaskan ranges to the south and closer to the coast can receive 250 inches to 500 inches of snow, as measured at the Anaktuvuk Pass weather station, the average summer temperatures are 3 °C as a low and 16 °C as a high. Arctic citadel, a history of exploration in the Brooks Range region of Northern Alaska, washington, D. C, U. S. Department of the Interior, National Park Service. Geologic and fossil locality maps of the part of the Howard Pass quadrangle and part of the adjacent Misheguk Mountain quadrangle, Western Brooks Range. U. S. Department of the Interior, U. S. Geological Survey, krumhardt, A. P. A. G. Harris, and K. F. Watts. U. S. Department of the Interior, U. S. Geological Survey, Alaska wilderness, exploring the Central Brooks Range 2nd ed. Berkeley, University of California Press. ISBN 0-520-24498-2 Mayfield, C. F. et al, reconnaissance geologic map of southeastern Misheguk Mountain quadrangle, Alaska. U. S. Department of the Interior, U. S. Geological Survey, gravity and magnetic maps of part of the Drenchwater Creek stratiform zinc-lead-silver deposit, Howard Pass quadrangle, northwestern Brooks Range, Alaska
32.
Greenland
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Greenland is an autonomous constituent country within the Danish Realm between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for more than a millennium. The majority of its residents are Inuit, whose ancestors began migrating from the Canadian mainland in the 13th century, Greenland is the worlds largest island. Three-quarters of Greenland is covered by the permanent ice sheet outside Antarctica. With a population of about 56,480, it is the least densely populated country in the world, the Arctic Umiaq Line ferry acts as a lifeline for western Greenland, connecting the various cities and settlements. Greenland has been inhabited off and on for at least the last 4,500 years by Arctic peoples whose forebears migrated there from what is now Canada, Norsemen settled the uninhabited southern part of Greenland beginning in the 10th century, and Inuit peoples arrived in the 13th century. The Norse colonies disappeared in the late 15th century, soon after their demise, beginning in 1499, the Portuguese briefly explored and claimed the island, naming it Terra do Lavrador. In the early 18th century, Scandinavian explorers reached Greenland again, to strengthen trading and power, Denmark-Norway affirmed sovereignty over the island. Greenland was settled by Vikings more than a thousand years ago, Vikings set sail from Greenland and Iceland, discovering North America nearly 500 years before Columbus reached Caribbean islands. Though under continuous influence of Norway and Norwegians, Greenland was not formally under the Norwegian crown until 1262, the Kingdom of Norway was extensive and a military power until the mid-14th century. Thus, the two kingdoms resources were directed at creating Copenhagen, Norway became the weaker part and lost sovereignty over Greenland in 1814 when the union was dissolved. Greenland became a Danish colony in 1814, and was made a part of the Danish Realm in 1953 under the Constitution of Denmark, in 1973, Greenland joined the European Economic Community with Denmark. However, in a referendum in 1982, a majority of the population voted for Greenland to withdraw from the EEC which was effected in 1985, Greenland contains the worlds largest and most northernly national park, Northeast Greenland National Park. Greenland is divided into four municipalities - Sermersooq, Kujalleq, Qaasuitsup and it also retains control of monetary policy, providing an initial annual subsidy of DKK3.4 billion, which is planned to diminish gradually over time. Greenland expects to grow its economy based on increased income from the extraction of natural resources, the capital, Nuuk, held the 2016 Arctic Winter Games. At 70%, Greenland has one of the highest shares of renewable energy in the world, the early Viking settlers named the island as Greenland. In the Icelandic sagas, the Norwegian-born Icelander Erik the Red was said to be exiled from Iceland for manslaughter, along with his extended family and his thralls, he set out in ships to explore an icy land known to lie to the northwest. After finding an area and settling there, he named it Grœnland
33.
Andes
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The Andes or Andean Mountains are the longest continental mountain range in the world. They are a range of highlands along the western edge of South America. This range is about 7,000 km long, about 200 to 700 km wide, the Andes extend from north to south through seven South American countries, Venezuela, Colombia, Ecuador, Peru, Bolivia, Argentina and Chile. Along their length, the Andes are split into several ranges, the Andes are the location of several high plateaus – some of which host major cities, such as Quito, Bogotá, Arequipa, Medellín, Sucre, Mérida and La Paz. The Altiplano plateau is the worlds second-highest after the Tibetan plateau and these ranges are in turn grouped into three major divisions based on climate, the Tropical Andes, the Dry Andes, and the Wet Andes. The Andes are the worlds highest mountain range outside of Asia, the highest mountain outside Asia, Mount Aconcagua, rises to an elevation of about 6,961 m above sea level. The peak of Chimborazo in the Ecuadorean Andes is farther from the Earths center than any other location on the Earths surface, the worlds highest volcanoes are in the Andes, including Ojos del Salado on the Chile-Argentina border, which rises to 6,893 m. The etymology of the word Andes has been debated, the majority consensus is that it derives from the Quechua word anti, which means east as in Antisuyu, one of the four regions of the Inca Empire. In the northern part of the Andes, the isolated Sierra Nevada de Santa Marta range is considered to be part of the Andes. The term cordillera comes from the Spanish word cordel, meaning rope, the Andes range is about 200 km wide throughout its length, except in the Bolivian flexure where it is about 640 kilometres wide. The Andes are the result of plate tectonics processes, caused by the subduction of oceanic crust beneath the South American plate. The main cause of the rise of the Andes is the compression of the rim of the South American Plate due to the subduction of the Nazca Plate. In the south, the Andes share a boundary with the former Patagonia Terrane. To the west, the Andes end at the Pacific Ocean, from a geographical approach, the Andes are considered to have their western boundaries marked by the appearance of coastal lowlands and a less rugged topography. The Andes Mountains also contain large quantities of iron ore located in mountains within the range. The Andean orogen has a series of bends or oroclines, the Bolivian Orocline is a seaward concave bending in the coast of South America and the Andes Mountains at about 18° S. At this point the orientation of the Andes turns from Northwest in Peru to South in Chile, the Andean segment north and south of the orocline have been rotated 15° to 20° counter clockwise and clockwise respectively. The Bolivian Orocline area overlaps with the area of maximum width of the Altiplano Plateau, the specific point at 18° S where the coastline bends is known as the Arica Elbow
34.
Rocky Mountains
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The Rocky Mountains, commonly known as the Rockies, are a major mountain range in western North America. The Rocky Mountains stretch more than 3,000 miles from the northernmost part of British Columbia, in western Canada, to New Mexico, in the Southwestern United States. Within the North American Cordillera, the Rockies are somewhat distinct from the Pacific Coast Ranges, the Rocky Mountains were initially formed from 80 million to 55 million years ago during the Laramide orogeny, in which a number of plates began to slide underneath the North American plate. The angle of subduction was shallow, resulting in a belt of mountains running down western North America. Since then, further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks, at the end of the last ice age, humans started to inhabit the mountain range. The first mention of their present name by a European was in the journal of Jacques Legardeur de Saint-Pierre in 1752, the Rocky Mountains are commonly defined as stretching from the Liard River in British Columbia south to the Rio Grande in New Mexico. The United States definition of the Rockies includes the Cabinet and Salish Mountains of Idaho and their counterparts north of the Kootenai River, the Columbia Mountains, are considered a separate system in Canada, lying to the west of the huge Rocky Mountain Trench. This runs the length of British Columbia from its beginnings in the middle Flathead River valley in western Montana to the bank of the Liard River. The Rockies vary in width from 70 to 300 miles, also west of the Rocky Mountain Trench, farther north and facing the Muskwa Range across the trench, are the Stikine Ranges and Omineca Mountains of the Interior Mountains system of British Columbia. A small area east of Prince George, British Columbia on the side of the Trench. In Canada geographers define three main groups of ranges, the Continental Ranges, Hart Ranges and Muskwa Ranges, the Muskwa and Hart Ranges together comprise what is known as the Northern Rockies. The western edge of the Rockies includes ranges such as the Wasatch near Salt Lake City, the Great Basin and Columbia River Plateau separate these sub-ranges from distinct ranges further to the west, most prominent among which are the Sierra Nevada, Cascade Range and Coast Mountains. The Rocky Mountain System within the United States is a United States physiographic region, the Rocky Mountains are notable for containing the highest peaks in central North America. The ranges highest peak is Mount Elbert located in Colorado at 14,440 feet above sea level, Mount Robson in British Columbia, at 12,972 feet, is the highest peak in the Canadian Rockies. The Continental Divide of the Americas is located in the Rocky Mountains, triple Divide Peak in Glacier National Park is so named because water that falls on the mountain reaches not only the Atlantic and Pacific, but Hudson Bay as well. Farther north in Alberta, the Athabasca and other rivers feed the basin of the Mackenzie River, see Rivers of the Rocky Mountains for a list of rivers. Human population is not very dense in the Rocky Mountains, with an average of four people per square kilometer, however, the human population grew rapidly in the Rocky Mountain states between 1950 and 1990. The 40-year statewide increases in range from 35% in Montana to about 150% in Utah
35.
Fennoscandian
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Fennoscandia, Fenno-Scandinavia, or the Fennoscandian Peninsula, is the geographical peninsula of the Nordic region comprising the Scandinavian Peninsula, Finland, Karelia, and the Kola Peninsula. It encompasses Finland, Norway and Sweden, as well as Murmansk Oblast, much of the Republic of Karelia and its name comes from the Latin words Fennia and Scandia. The term was first used by the Finnish geologist Wilhelm Ramsay in 1898, geologically, the area is distinct because its bedrock is Archaean granite and gneiss with very little limestone, in contrast to adjacent areas in Europe
36.
Northern Hemisphere
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The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined as being in the celestial hemisphere relative to the invariable plane of the solar system as Earths North pole. Due to the Earths axial tilt, winter in the Northern Hemisphere lasts from the December solstice to the March Equinox, the dates vary each year due to the difference between the calendar year and the astronomical year. Its surface is 60. 7% water, compared with 80. 9% water in the case of the Southern Hemisphere, the Arctic is the region north of the Arctic Circle. Its climate is characterized by cold winters and cool summers, precipitation mostly comes in the form of snow. The Arctic experiences some days in summer when the Sun never sets, the duration of these phases varies from one day for locations right on the Arctic Circle to several months near the North Pole, which is the middle of the Northern Hemisphere. Between the Arctic Circle and the Tropic of Cancer lies the Northern Temperate Zone, the changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. However, a temperate climate can have very unpredictable weather, tropical regions are generally hot all year round and tend to experience a rainy season during the summer months, and a dry season during the winter months. In the Northern Hemisphere, objects moving across or above the surface of the Earth tend to turn to the right because of the coriolis effect, as a result, large-scale horizontal flows of air or water tend to form clockwise-turning gyres. These are best seen in circulation patterns in the North Atlantic. For the same reason, flows of air down toward the surface of the Earth tend to spread across the surface in a clockwise pattern. Thus, clockwise air circulation is characteristic of high pressure weather cells in the Northern Hemisphere, conversely, air rising from the northern surface of the Earth tends to draw air toward it in a counterclockwise pattern. Hurricanes and tropical storms spin counter-clockwise in the Northern Hemisphere, the shadow of a sundial moves clockwise in the Northern Hemisphere. When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere, the North Pole faces away from the galactic center of the Milky Way. The Northern Hemisphere is home to approximately 6.57 billion people which is around 90% of the total human population of 7.3 billion people
37.
Southern Hemisphere
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The Southern Hemisphere is the half sphere of Earth which is south of the equator. It contains all or parts of five continents, four oceans and its surface is 80. 9% water, compared with 60. 7% water in the case of the Northern Hemisphere, and it contains 32. 7% of Earths land. Due to the tilt of Earths rotation relative to the Sun, September 22 or 23 is the vernal equinox and March 20 or 21 is the autumnal equinox. The South Pole is in the middle of the southern hemispherical region, Southern Hemisphere climates tend to be slightly milder than those at similar latitudes in the Northern Hemisphere, except in the Antarctic which is colder than the Arctic. This is because the Southern Hemisphere has significantly more ocean and much land, water heats up. In the Southern Hemisphere the sun passes from east to west through the north, sun-cast shadows turn anticlockwise throughout the day and sundials have the hours increasing in the anticlockwise direction. Cyclones and tropical storms spin clockwise in the Southern Hemisphere due to the Coriolis effect, the southern temperate zone, a subsection of the Southern Hemisphere, is nearly all oceanic. Forests in the Southern Hemisphere have special features which set apart from those in the Northern Hemisphere. Both Chile and Australia share, for example, unique species or Nothofagus. The eucalyptus is native to Australia but is now planted in Southern Africa and Latin America for pulp production and, increasingly. Approximately 800,000,000 humans live in the Southern Hemisphere and this is due to the fact that there is significantly less land in the Southern Hemisphere than in the Northern Hemisphere. Africa Antarctica Asia Australia South America Zealandia Media related to Southern Hemisphere at Wikimedia Commons
38.
Southern Ocean
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As such, it is regarded as the fourth-largest of the five principal oceanic divisions, smaller than the Pacific, Atlantic, and Indian Oceans but larger than the Arctic Ocean. This ocean zone is cold, northward flowing waters from the Antarctic mix with warmer subantarctic waters. By way of his voyages in the 1770s, Captain James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Oceans northern boundary or even existence, considering the part of the Pacific, Atlantic. Others regard the seasonally-fluctuating Antarctic Convergence as the natural boundary, Borders and names for oceans and seas were internationally agreed when the International Hydrographic Bureau, the precusor to the IHO, convened the First International Conference on 24 July 1919. The IHO then published these in its Limits of Oceans and Seas, Australian authorities regard the Southern Ocean as lying immediately south of Australia. Map publishers using the term Southern Ocean on their maps include Hema Maps, Southern Ocean is an obsolete name for the Pacific Ocean or South Pacific, coined by Vasco Núñez de Balboa, the first European to discover it, who approached it from the north. The South Seas is an archaic synonym. A1745 British Act of Parliament established a prize for discovering a Northwest Passage to the Western and Southern Ocean of America, authors using Southern Ocean to name the waters encircling the unknown southern polar regions used varying limits. James Cooks account of his second voyage implies New Caledonia borders it, peacocks 1795 Geographical Dictionary said it lay to the southward of America and Africa, John Payne in 1796 used 40 degrees as the northern limit, the 1827 Edinburgh Gazetteer used 50 degrees. The United Kingdoms South Australia Act 1834 described the waters forming the southern limit of the new colony of South Australia as the Southern Ocean. The Colony of Victorias Legislative Council Act of 1881 delimited part of the division of Bairnsdale as along the New South Wales boundary to the Southern ocean. The limit then followed the west coast of Tasmania southwards to the South East Cape and then went eastwards to Broughton Island, New Zealand, the northern limits of the Southern Ocean were moved southwards in the IHOs 1937 second edition of the Limits of Oceans and Seas. From this edition, much of the northern limit ceased to abut land masses. As is discussed in detail below, prior to the 2002 edition the limits of oceans explicitly excluded the seas lying within each of them. The Great Australian Bight was unnamed in the 1928 edition, and it therefore encompassed former Southern Ocean waters but was technically not inside any of the three adjacent oceans by 1937. To perform direct comparisons of current and former limits of oceans it is necessary to consider, or at least be aware of, the limits of the Atlantic, Pacific and Indian Oceans have therefore been extended South to the Antarctic Continent. The IHO readdressed the question of the Southern Ocean in a survey in 2000, of its 68 member nations,28 responded, and all responding members except Argentina agreed to redefine the ocean, reflecting the importance placed by oceanographers on ocean currents
39.
Antarctica
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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 square kilometres, 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 km in thickness, Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with precipitation of only 200 mm along the coast. The temperature in Antarctica has reached −89.2 °C, though the average for the quarter is −63 °C. Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Organisms native to Antarctica include many types of algae, bacteria, fungi, plants, protista, vegetation, where it occurs, is tundra. The continent, however, remained neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources. In 1895, the first confirmed landing was conducted by a team of Norwegians, Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then, the treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continents ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations, the name Antarctica is the romanised version of the Greek compound word ἀνταρκτική, feminine of ἀνταρκτικός, meaning opposite to the Arctic, opposite to the north. Aristotle wrote in his book Meteorology about an Antarctic region in c.350 B. C, marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A. D. Before acquiring its present geographical connotations, the term was used for locations that could be defined as opposite to the north. For example, the short-lived French colony established in Brazil in the 16th century was called France Antarctique, the first formal use of the name Antarctica as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. Antarctica has no population and there is no evidence that it was seen by humans until the 19th century. Explorer Matthew Flinders, in particular, has credited with popularising the transfer of the name Terra Australis to Australia. Cook came within about 120 km of the Antarctic coast before retreating in the face of ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals, according to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820, von Bellingshausen, Edward Bransfield, and Nathaniel Palmer
40.
Mount Kilimanjaro
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Mount Kilimanjaro, with its three volcanic cones, Kibo, Mawenzi, and Shira, is a dormant volcano in Tanzania. It is the highest mountain in Africa, and rises approximately 4,900 m from its base to 5,895 metres above sea level, the first recorded ascent to the summit of the mountain was by Hans Meyer and Ludwig Purtscheller in 1889. The mountain is part of the Kilimanjaro National Park and is a major climbing destination, the mountain has been the subject of many scientific studies because of its shrinking glaciers. Kilimanjaro rises approximately 4,900 m from its base in the plains near the municipality of Moshi to its summit height of 5,895 metres. Kilimanjaro is the highest volcano outside South America, Kilimanjaro is a large stratovolcano and is composed of three distinct volcanic cones, Kibo, the highest, Mawenzi at 5,149 metres, and Shira, the shortest at 4,005 metres. Mawenzi and Shira are extinct, while Kibo is dormant and could erupt again, Uhuru Peak is the highest summit on Kibos crater rim. The Tanzania National Parks Authority, a Tanzanian governmental agency, and that height is based on a British Ordnance Survey in 1952. Since then, the height has been measured as 5,892 metres in 1999,5,891 metres in 2008, the interior of the volcanic edifice is poorly known, given the lack of large scale erosion that could have exposed the interiors of the volcano. Shira is topped by a plateau at 3,800 metres. The remnant caldera rim has been degraded deeply by erosion, before the caldera formed and erosion began, Shira might have been between 4,900 m and 5,200 m high. It is mostly composed of lavas with some pyroclastics. The formation of the caldera was accompanied by lava emanating from ring fractures, two cones formed subsequently, the phonolitic one at the northwest end of the ridge and the doleritic Platzkegel in the caldera centre. Both Mawenzi and Kibo began erupting about 1 million years ago and they are separated by the Saddle Plateau at 4,400 metres elevation. The youngest dated rocks at Mawenzi are about 448,000 years old, Mawenzi forms a horseshoe shaped ridge with pinnacles and ridges opening to the northeast which has a tower like shape resulting from deep erosion and a mafic dyke swarm. Several large cirques cut into the ring, the largest of these sits on top of the Great Barranco gorge, also notable are the Ost and West Barrancos on the northeastern side of the mountain. Most of the side of the mountain has been removed by erosion. Mawenzi has a peak named Neumann Tower. Kibo is the largest cone and is more than 15 miles wide at the Saddle Plateau altitude, the last activity here has been dated to between 150,000 and 200,000 years ago and created the current Kibo summit crater
41.
Prudhoe Bay, Alaska
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Prudhoe Bay /ˈpruːdoʊ/ or Sagavanirktok is a census-designated place located in North Slope Borough in the U. S. state of Alaska. As of the 2010 census, the population of the CDP was 2,174 people, however, the airport, lodging, and general store are located at Deadhorse, the rigs and processing facilities are located on scattered gravel pads laid atop the tundra. It is only during winter that the surface is hard enough to support heavy equipment, Prudhoe Bay is the unofficial northern terminus of the Pan-American Highway. The Bay itself is still 10 miles further north than a security checkpoint so open water is not visible from the highway, tours must be arranged in advance to see the Arctic Ocean and the Bay itself. Prudhoe Bay was named in 1826 by British explorer Sir John Franklin after his classmate Captain Algernon Percy, Franklin traveled along the coast from the mouth of the Mackenzie River almost to Point Barrow. Prudhoe Bay is located at 70°19′32″N 148°42′41″W, according to the United States Census Bureau, the CDP has a total area of 558.0 square miles of which,416.3 square miles of it is land and 141.8 square miles of it is water. The total area is 25. 40% water, Prudhoe Bay, along with similar communities on the North shore of Alaska, features a Tundra climate. Winters are long, very cold and due to its location above the Arctic Circle, summers, while bringing long daylight hours are still cold with temperatures just above freezing. As of the 2010 United States Census, there were 2,174 people residing in the CDP. The racial makeup of the CDP was 83. 0% White,1. 9% Black,7. 5% Native American,1. 5% Asian,0. 1% Pacific Islander,0. 3% from some other race and 1. 6% from two or more races. 4. 0% were Hispanic or Latino of any race, Prudhoe Bay is adjacent to the largest oil field in the United States. Prudhoe Bay is classified as an isolated town/Sub-Regional Center and it is found in EMS Region 6A in the North Slope Region. Emergency Services have limited highway, coastal, and airport access, Emergency service is provided by a paid Emergency Medical Services unit and Fairweather Deadhorse Medical Clinic. Auxiliary health care is provided by oil company medical staff and the Greater Prudhoe Bay Fire Dept, individuals requiring hospital care are usually transported to the nearest hospital/medical center, Sammuel Simmonds Memorial Hospital, in Barrow, Alaska. Because no roads connect Prudhoe Bay to Barrow, individuals are transported by helicopter or air ambulance,2006 Alaskan oil spill Alaska Pipeline Ice Road Truckers Media related to Prudhoe Bay, Alaska at Wikimedia Commons Prudhoe Bay information website
42.
Lena River
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The Lena is the easternmost of the three great Siberian rivers that flow into the Arctic Ocean. It is the 11th longest river in the world and has the 9th largest watershed and it is also the 3rd largest river in Asia. It is the largest among the rivers watershed is entirely within the Russian territorial boundaries. From Yakutsk it enters the lowlands and flows north until joined by its tributary the Aldan River and its most important left-hand tributary. In the upper section west and northwest of Lake Baikal the river flows mostly north and it turns west and then south losing another 600 meters in 128 km, to Chanchur, where there is a ranger station. 4222, Kachug, start of navigation, road to Irkutsk,4197, Verkholensk, mouth of the Kulenga River, northwest through mountains, Tutura River. 4108, Zhigalovo, start of service, including hydrofoil to Ust-Kut. In the central section the river flows mostly northeast,3705, Ust-Kut, northwest of the northern tip of Lake Baikal. In Cossack times, this was the site of a portage between the Yenesei and Lena, today it is the point where the Baikal-Amur Mainline railway crosses the Lena on a bridge and it handles 80% of cargo in the Sakha Republic region. 3397, Kirensk, port and former Cossack portage,3101, The devils path, a section treacherous in flood. 3096, Shcheki, a section with cliffs and twists. 2955, Vitim, and Vitim River from the south and we are now northeast of Lake Baikal. Many dead trees in the water,2931, Peledui, Peledui River, ship repair company and salt mines. 2744, Lensk, the most important port between Kirensk and Yakutsk, road 230 km north to the Mir Mine. Here was a point of the Perlinsky Trakht, a former courier route. Lena turns southeast and then northeast,2587, Chepaevo,2547, Macha,2937, Olyokminsk, Olyokma River from the south. River widens to 2 km and has extensive flood plains,2213, Uritskoe, 2030-1850, Lena Pillars, cliffs along the right bank. 1820, Mokhsogollokh, ferry and paved road to Yakutsk on the opposite bank,1805, Pokrovsk, downstream, Tabaga Cliffs, narrows, power line and planned site of bridge for the Amur Yakutsk Mainline railroad
43.
Yana River
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The Yana River, is a river in Sakha in Russia, located between the Lena to the west and the Indigirka to the east. It is 872 kilometres long, while the upper Yana is 1,320 kilometres long and its drainage basin covers 238,000 square kilometres, and its annual discharge totals approximately 25 cubic kilometres. Most of this occurs in May and June as the ice on the river breaks up. The Yana freezes up on the surface in October and stays under the ice until late May or early June, in the Verkhoyansk area, it stays frozen to the bottom for 70 to 110 days, and partly frozen for 220 days of the year. The river begins at the confluence of the rivers Sartang and Dulgalakh, as the Yana flows into the Yana Bay of the Laptev Sea, it forms a huge river delta covering 10,200 square kilometres. Yarok is a flat island located east of the main mouths of the Yana. The whole Yana basin is under continuous permafrost and most is larch woodland grading to tundra north of about 70°N, the principal tributaries of the Yana are, Adycha, Oldzho, Abyrabyt, Bytantay. Most of these tributaries are rivers flowing from the high Verkhoyansk Mountains. Verkhoyansk, Batagay, Ust-Kuyga, Nizhneyansk are the ports on the Yana. The Yana basin is the site of the so-called Pole of Cold of Russia, where the lowest recorded temperatures in the Northern Hemisphere are found. In the winter, temperatures in the centre of the average as low as −51 °C and have reached as low as −71 °C though in the mountains it is believed that temperatures have reached −82 °C. Yakut folklore says that, at such temperatures, if you shout to a friend and they hear you. However, when spring comes the words thaw and one can hear everything that was months ago. The Yana River area is the first known site of habitation in the Arctic. In 1633–38 Ilya Perfilyev and Ivan Rebrov sailed down the Lena and east along the Arctic coast to the mouth of the Yana, in 1636–42 Elisei Buza followed essentially the same route. In 1638–40, Poznik Ivanov ascended a tributary of the lower Lena, crossed the Verkhoyansk Range to the upper Yana and then crossed the Chersky Range to the Indigirka. During one year and two days the expedition covered 25,000 kilometres, of which 4,200 kilometres were up rivers, william Barr, Baron Eduard Von Tolls Last Expedition. Alexander von Bunge & Baron Eduard Von Toll, The Expedition to the New Siberian Islands and the Jana country, equipped by the Imperial Academy of Sciences
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Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
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Pleistocene
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The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the worlds most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period, the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, all of these stages were defined in southern Europe. In addition to this subdivision, various regional subdivisions are often used. Charles Lyell introduced the term pleistocene in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today and this distinguished it from the older Pliocene Epoch, which Lyell had originally thought to be the youngest fossil rock layer. The Pleistocene has been dated from 2.588 million to 11,700 years before present and it covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9640 BC, the IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75°06 N 42°18 W, the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils, Discoaster pentaradiatus, the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. The revised definition of the Quaternary, by pushing back the date of the Pleistocene to 2.58 Ma. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places and it is estimated that, at maximum glacial extent, 30% of the Earths surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the sheet, a few hundred kilometres in North America. The mean annual temperature at the edge of the ice was −6 °C, during interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global, antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap, there were glaciers in New Zealand and Tasmania. The current decaying glaciers of Mount Kenya, Mount Kilimanjaro, glaciers existed in the mountains of Ethiopia and to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one, the Cordilleran ice sheet covered the North American northwest, the east was covered by the Laurentide
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Aufeis
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Aufeis, is a sheet-like mass of layered ice that forms from successive flows of ground water during freezing temperatures. This form of ice is also called overflow, icings, or the Russian term, the term was first used in 1859 by A. T. von Middendorff following his observations of the phenomenon in northern Siberia. Aufeis accumulates during winter along stream and river valleys in arctic and subarctic environments and it forms by upwelling of river water behind ice dams, or by ground-water discharge. The latter mechanism prevails in high-gradient alpine streams as they freeze solid, successive ice layers can lead to aufeis accumulations that are several meters thick. Aufeis typically melts out during summer and will form in the same place year after year. Sheets of aufeis may block stream channels and cause their flood plains to widen as spring floodwaters are forced to flow around the ice, research on aufeis has to a large extent been motivated by the variety of engineering problems the ice sheets can cause. Culverts and pipelines can actually help to block flow and lead to the development of more extensive aufeis. Aufeis can present a danger to recreational boaters even during summer months. Breaking dams of aufeis can also cause flash floods downriver, proper scouting and precautions when choosing campsites can minimize these risks. In late 2011, Mongolia planned to test the use and storage of artificial naleds as a way of cooling Ulan Bator in the hot Mongolian summer, sheets of aufeis have been observed in Alaska, Arctic Canada, Russia, and Mongolia. Wang, Bronwen, Vohden, Jim, et al, gough, Larry P. Day, Warren C. eds. Aufeis Accumulations in Stream Bottoms in Arctic and Subarctic Environments as an Indicator of Geologic Structure, recent U. S. Geological Survey Studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada — Results of a 5-Year Project. U. S. Department of the Interior and U. S. Geological Survey, media related to Aufeis at Wikimedia Commons
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Palsa
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A palsa is a low, often oval, frost heave occurring in polar and subpolar climates, which contain permanently frozen ice lenses. Palsas are characteristically found in areas with discontinuous permafrost, and in areas they may be the only reliable surface evidence of permafrost. Surface water, found in bogs, enhances palsa formation in areas called palsa bogs, palsas may be initiated in areas of a moor or bog where the winter freezing front penetrates relatively faster than surrounding areas, perhaps due to an unusually thin cover of snow. The lack of insulation provided by thick snow permits much deeper freezing in winter. This ice may then last through the summer with a persistent bump of up to several cm due to frost heave. The elevated surface of a palsa will tend also to have snow cover, allowing greater winter cooling, while in summer the surface material will dry out. Thus the interior temperature is lower than that of adjacent ground. This contributes to the formation of an ice lens which grows by drawing up surrounding water, changes in surface moisture and vegetation will then be such as to preserve the newly formed permafrost. The overlying soil layer is lifted up by frost heaving. In cross-section, the ice cores of a palsa show layering, the pressing out of water from the pores is not crucial, however, since the boggy soil is water-saturated and thus always provides enough water for ice core growth. Palsas appear to go through a cycle that eventually leads to thawing. The fact that palsas in various stages of growth and decay occur together shows that their collapse is not necessarily indicative of climatic change, all that is usually left after a palsa collapses is a depression surrounded by a rim. Palsa forms include mounds, moderately straight ridges, and winding ridges, widths are commonly 10–30 m, and lengths 15–150 m. However, lengths of up to 500 m have reported for esker-like palsa ridges running parallel to the gradient of a bog. Heights range from less than 1 m to about 10 m at a maximum above the surrounding area, large forms tend to be considerably less conical than small ones. In places, palsas combine to form complexes several hundred meters in extent, the permafrost core contains ice lenses no thicker than 2–3 cm, though locally lenses up to almost 40 cm thick have been described. Palsas form in groups or fields and the individual palsa can show its age difference from the others, Palsa surfaces are frequently traversed by open cracks, caused by doming, frost cracking, or desiccation. The vegetation of a palsa may comprise low shrubs and lichen in addition to the sedges characterizing the peat, also, the higher a palsa grows the dryer the peat covering the palsa becomes leading to more insulation which protects the inner core from melting
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Pingo
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A pingo, also called a hydrolaccolith, is a mound of earth-covered ice found in the Arctic and subarctic that can reach up to 70 metres in height and up to 600 m in diameter. The term originated as the Inuvialuktun word for a small hill, a pingo is a periglacial landform, which is defined as a nonglacial landform or process linked to colder climates. Periglacial suggests an environment located on the margin of past glaciers, however, freeze and thaw cycles influence landscapes outside areas of past glaciation. Therefore, periglacial environments are anywhere that freezing and thawing modify the landscape in a significant manner and they are essentially formed by ground ice which develops during the winter months as temperatures fall. Pingos can only form in a permafrost environment, evidence of collapsed pingos in an area suggests that there was once permafrost. Hydrostatic pingos form as a result of pressure on water from permafrost. Permafrost rises to the bodys former floor. Pore water is expelled in front of the rising permafrost, and the pressure causes the frozen ground to rise. The shape and size of a hydrostatic or closed system pingo is often similar to the body of water that it originated from and they can vary from symmetrical conical domes to asymmetric, elongate hills. Hydraulic pingos result from groundwater flowing from a source, i. e. subpermafrost or intrapermafrost aquifers. Hydrostatic pressure initializes the formation of the ice core as water is pushed up, open-system pingos have no limitations to the amount of water available unless the aquifers freeze. They often occur at the base of slopes and are known as Greenland type. The groundwater is put under pressure and forces the ground up as it makes an expanding ice core. It is not the pressure itself that forces the ground up. These are often formed in a thin, discontinuous permafrost and these conditions allow an ice core to form, but also provide it with a supply of artesian ground water. If water pressure entering an artesian pingo is strong enough, it can lift the pingo up allowing a sub-pingo water lens to form underneath, however, if the water lens starts to leak water it can cause subsidence which can compromise the structure. These pingos are often oval or oblong shaped and it is still not entirely understood why open system or hydraulic pingos normally occur in unglaciated terrain. Pingos usually grow only a couple centimetres per year, with Ibyuk Pingo growing at a rate of 2 centimetres a year, the process that creates pingos is believed to be closely related to frost heaving
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