The cryosphere, derived from the Greek word kryos for "frost" or "icy cold", is the term which collectively describes the portions of the Earth’s surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground (which includes permafrost). The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, and atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in global climate and in climate model response to global change. Frost on black pipes Frost is a solid deposition of water vapor from saturated air. ... This article is about water ice. ... This article is about Earth as a planet. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... For other uses, see Solid (disambiguation). ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ... This article is about water ice. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... Austrias longest glacier, the Pasterze, winds its 8 km (5 mile) route at the foot of Austrias highest mountain, the Grossglockner A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. ... An ice cap is a dome-shaped ice mass that covers less than 50,000 km² of land area (usually covering a highland area). ... An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (19,305 mile²).[1] The only current ice sheets are in Antarctica and Greenland; during the last ice age at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much... In geology, permafrost or permafrost soil is soil at or below the freezing point of water (0°C or 32°F) for two or more years. ... Global climate is a concept that has never been defined, but roughly speaking it is meant to express the average temperature, average precipitation, average intensity of winds and similar features of Earths atmosphere and the whole planets surface. ... It has been suggested that this article or section be merged with Feedback loop. ... For other uses, see Cloud (disambiguation). ... Water covers 70% of the Earths surface. ... It has been suggested that this article or section be merged with Feedback loop. ... Global climate is a concept that has never been defined, but roughly speaking it is meant to express the average temperature, average precipitation, average intensity of winds and similar features of Earths atmosphere and the whole planets surface. ... Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. ...

Overview of the Cryosphere and its larger components, from the UN Environment Programme Global Outlook for Ice and Snow.

Image File history File links Size of this preview: 800 × 319 pixelsFull resolution (2703 × 1079 pixel, file size: 1. ... Image File history File links Size of this preview: 800 × 319 pixelsFull resolution (2703 × 1079 pixel, file size: 1. ...

Structure

Frozen water occurs on the Earth’s surface primarily as snow cover, freshwater ice in lakes and rivers, sea ice, glaciers, ice sheets, and frozen ground and permafrost (perennially-frozen ground). The residence time of water in each of these cryospheric sub-systems varies widely. Snow cover and freshwater ice are essentially seasonal, and most sea ice, except for ice in the central Arctic, lasts only a few years if it is not seasonal. A given water particle in glaciers, ice sheets, or ground ice, however, may remain frozen for 10-100,000 years or longer, and deep ice in parts of East Antarctica may have an age approaching 1 million years. This article is about water ice. ... This article is about Earth as a planet. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... This article is about water ice. ... Lake Clearwater, Ontario, Canada A lake is a large body of water, usually fresh water, surrounded by land. ... For the Second World War frigate class, see River class frigate The Murray River in Australia A waterfall on the Ova da Fedoz, Switzerland A river is a large natural waterway. ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ... Austrias longest glacier, the Pasterze, winds its 8 km (5 mile) route at the foot of Austrias highest mountain, the Grossglockner A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. ... An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres). ... In geology, permafrost or permafrost soil is soil at or below the freezing point of water (0°C or 32°F) for two or more years. ... The red line indicates the 10°C isotherm in July, commonly used to define the Arctic region border Satellite image of the Arctic surface The Arctic is the region around the Earths North Pole, opposite the Antarctic region around the South Pole. ... Austrias longest glacier, the Pasterze, winds its 8 km (5 mile) route at the foot of Austrias highest mountain, the Grossglockner A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. ... An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres). ... East Antarctica, also called Greater Antarctica, (80° S 80° E) is one of the two major regions of Antarctica, lying on the Indian Ocean side of the Transantarctic Mountains and comprising Coats Land, Queen Maud Land, Enderby Land, Mac. ...

The majority of the world’s ice volume is in Antarctica, principally in the East Antarctic ice sheet. In terms of areal extent, however, Northern Hemisphere winter snow and ice extent comprise the largest area, amounting to an average 23% of hemispheric surface area in January. The large areal extent and the important climatic roles of snow and ice, related to their unique physical properties, indicate that the ability to observe and model snow and ice-cover extent, thickness, and physical properties (radiative and thermal properties) is of particular significance for climate research. An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (19,305 mile²).[1] The only current ice sheets are in Antarctica and Greenland; during the last ice age at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much... Northern hemisphere highlighted in yellow. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... This article is about water ice. ... Climatology is the science that studies climates and investigates their phenomena and causes. ...

There are several fundamental physical properties of snow and ice that modulate energy exchanges between the surface and the atmosphere. The most important properties are the surface reflectance (albedo), the ability to transfer heat (thermal diffusivity), and the ability to change state (latent heat). These physical properties, together with surface roughness, emissivity, and dielectric characteristics, have important implications for observing snow and ice from space. For example, surface roughness is often the dominant factor determining the strength of radar backscatter (Hall 1996). Physical properties such as crystal structure, density, and liquid-water content are important factors affecting the transfers of heat and water and the scattering of microwave energy. For other uses, see Atmosphere (disambiguation). ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... In thermochemistry, latent heat is the amount of energy in the form of heat released or absorbed by a substance during evaporation. ... The emissivity of a material (usually written ) is the ratio of energy radiated by the material to energy radiated by a black body at the same temperature. ... A dielectric is a physical model commonly used to describe how an electric field behaves inside a material. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... This article is about water ice. ... For other uses, see Radar (disambiguation). ... Backscatter is the reflection of waves, particles, or signals back to the direction they came from. ... For other uses, see Crystal (disambiguation). ... This article is about the type of Electromagnetic radiation. ...

The surface reflectance of incoming solar radiation is important for the surface energy balance (SEB). It is the ratio of reflected to incident solar radiation, commonly referred to as albedo. Climatologists are primarily interested in albedo integrated over the shortwave portion of the electromagnetic spectrum (~0.3 to 3.5 nm), which coincides with the main solar energy input. Typically, albedo values for non-melting snow-covered surfaces are high (~80-90%) except in the case of forests (see textbox on pg. 266). The higher albedos for snow and ice cause rapid shifts in surface reflectivity in autumn and spring in high latitudes, but the overall climatic significance of this increase is spatially and temporally modulated by cloud cover. (Planetary albedo is determined principally by cloud cover, and by the small amount of total solar radiation received in high latitudes during winter months.) Summer and autumn are times of high-average cloudiness over the Arctic Ocean so the albedo feedback associated with the large seasonal changes in sea-ice extent is greatly reduced. Groisman et al. (1994a) observed that snow cover exhibited the greatest influence on the Earth radiative balance in the spring (April to May) period when incoming solar radiation was greatest over snow-covered areas. Solar irradiance spectrum at top of atmosphere. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... Wikipedia does not yet have an article with this exact name. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... A solid-state, analog shortwave receiver Shortwave radio operates between the frequencies of 3 MHz (3,000 kHz) and 30 MHz (30,000 kHz) [1] and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than... Legend γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High... Albedo is the ratio of reflected to incident electromagnetic radiation. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... In optics, reflectivity is the reflectance (the ratio of reflected power to incident power, generally expressed in decibels or percentage) at the surface of a material so thick that the reflectance does not change with increasing thickness; , the intrinsic reflectance of the surface, irrespective of other parameters such as the... Cloud cover (also known as cloudiness, cloudage or cloud amount) refers to the fraction of the sky obscured by clouds when observed from a particular location. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... Cloud cover (also known as cloudiness, cloudage or cloud amount) refers to the fraction of the sky obscured by clouds when observed from a particular location. ... Solar irradiance spectrum at top of atmosphere. ... Latitude, denoted φ, gives the location of a place on Earth north or south of the Equator. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... It has been suggested that this article or section be merged with Feedback loop. ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ... This article is about Earth as a planet. ... Irradiance, radiant emittance, and radiant exitance are radiometry terms for the power of electromagnetic radiation at a surface, per unit area. ... Solar irradiance spectrum at top of atmosphere. ...

The thermal properties of cryospheric elements also have important climatic consequences. Snow and ice have much lower thermal diffusivities than air. Thermal diffusivity is a measure of the speed at which temperature waves can penetrate a substance. As shown in the box, snow and ice are many orders of magnitude less efficient at diffusing heat than air. Snow cover insulates the ground surface, and sea ice insulates the underlying ocean, decoupling the surface-atmosphere interface with respect to both heat and moisture fluxes. The flux of moisture from a water surface is eliminated by even a thin skin of ice, whereas the flux of heat through thin ice continues to be substantial until it attains a thickness in excess of 30 to 40 cm. However, even a small amount of snow on top of the ice will dramatically reduce the heat flux and slow down the rate of ice growth. The insulating effect of snow also has major implications for the hydrological cycle. In non-permafrost regions, the insulating effect of snow is such that only near-surface ground freezes and deep-water drainage is uninterrupted (Lynch-Stieglitz 1994). Example of a thermal column between the ground and a cumulus This article is about the atmospheric phenomenon. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... This article is about water ice. ... Example of a thermal column between the ground and a cumulus This article is about the atmospheric phenomenon. ... Look up air in Wiktionary, the free dictionary. ... In heat transfer analysis, thermal diffusivity (symbol: ) is the ratio of thermal conductivity to heat capacity. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... This article is about water ice. ... An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. ... Look up air in Wiktionary, the free dictionary. ... The water cycle is known scientifically as the hydrologic cycle. ...

While snow and ice act to insulate the surface from large energy losses in winter, they also act to retard warming in the spring and summer because of the large amount of energy required to melt ice (the latent heat of fusion, 3.34 x 10⁵ J/kg at 0°C). However, the strong static stability of the atmosphere over areas of extensive snow or ice tends to confine the immediate cooling effect to a relatively shallow layer, so that associated atmospheric anomalies are usually short-lived and local to regional in scale (Cohen and Rind 1991). In some areas of the world such as Eurasia, however, the cooling associated with a heavy snowpack and moist spring soils is known to play a role in modulating the summer monsoon circulation (e.g., Vernekar et al. 1995). Gutzler and Preston (1997) recently presented evidence for a similar snow-summer circulation feedback over the southwestern United States. Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... This article is about water ice. ... In thermochemistry, latent heat is the amount of energy in the form of heat released or absorbed by a substance during evaporation. ... For other uses, see Atmosphere (disambiguation). ... For other uses, see Eurasia (disambiguation). ... Bold text[[ // [[Image:Media:Example. ... It has been suggested that this article or section be merged with Feedback loop. ...

The role of snow cover in modulating the monsoon is just one example of a short-term cryosphere-climate feedback involving the land surface and the atmosphere. From Figure 1 it can be seen that there are numerous cryosphere-climate feedbacks in the global climate system. These operate over a wide range of spatial and temporal scales from local seasonal cooling of air temperatures to hemispheric-scale variations in ice sheets over time-scales of thousands of years. The feedback mechanisms involved are often complex and incompletely understood. For example, Curry et al. (1995) showed that the so-called “simple” sea ice-albedo feedback involved complex interactions with lead fraction, melt ponds, ice thickness, snow cover, and sea-ice extent. Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... It has been suggested that this article or section be merged with Feedback loop. ... For other uses, see Atmosphere (disambiguation). ... Global climate is a concept that has never been defined, but roughly speaking it is meant to express the average temperature, average precipitation, average intensity of winds and similar features of Earths atmosphere and the whole planets surface. ... An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (19,305 mile²).[1] The only current ice sheets are in Antarctica and Greenland; during the last ice age at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much... It has been suggested that this article or section be merged with Feedback loop. ...

Snow

Snow cover has the second-largest areal extent of any component of the cryosphere, with a mean maximum areal extent of approximately 47 million km². Most of the Earth’s snowcovered area (SCA) is located in the Northern Hemisphere, and temporal variability is dominated by the seasonal cycle; Northern Hemisphere snow-cover extent ranges from 46.5 million km² in January to 3.8 million km² in August (Robinson et al. 1993). North American winter SCA has exhibited an increasing trend over much of this century (Brown and Goodison 1996; Hughes et al. 1996) largely in response to an increase in precipitation (Groisman and Easterling 1994). However, the available satellite data show that the hemispheric winter snow cover has exhibited little interannual variability over the 1972-1996 period, with a coefficient of variation (COV=s.d./mean) for January Northern Hemisphere snow cover of < 0.04. According to Groisman et al. (1994a) Northern Hemisphere spring snow cover should exhibit a decreasing trend to explain an observed increase in Northern Hemisphere spring air temperatures this century. Preliminary estimates of SCA from historical and reconstructed in situ snow-cover data suggest this is the case for Eurasia, but not for North America, where spring snow cover has remained close to current levels over most of this century (Brown 1997). Because of the close relationship observed between hemispheric air temperature and snow-cover extent over the period of satellite data (IPCC 1996), there is considerable interest in monitoring Northern Hemisphere snow-cover extent for detecting and monitoring climate change. Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... Northern hemisphere highlighted in yellow. ... For alternate uses of time, see Time (disambiguation) or see TIME (magazine). ... Northern hemisphere highlighted in yellow. ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... For other uses, see Satellite (disambiguation). ... Northern hemisphere highlighted in yellow. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... Northern hemisphere highlighted in yellow. ... Northern hemisphere highlighted in yellow. ... Fig. ... In situ is a Latin phrase meaning in the place. ... For other uses, see Eurasia (disambiguation). ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... For other uses, see Satellite (disambiguation). ... Northern hemisphere highlighted in yellow. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 450,000 years For current global climate change, see Global warming. ...

Snow cover is an extremely important storage component in the water balance, especially seasonal snowpacks in mountainous areas of the world. Though limited in extent, seasonal snowpacks in the Earth’s mountain ranges account for the major source of the runoff for stream flow and groundwater recharge over wide areas of the midlatitudes. For example, over 85% of the annual runoff from the Colorado River basin originates as snowmelt. Snowmelt runoff from the Earth’s mountains fills the rivers and recharges the aquifers that over a billion people depend on for their water resources. Further, over 40% of the world’s protected areas are in mountains, attesting to their value both as unique ecosystems needing protection and as recreation areas for humans. Climate warming is expected to result in major changes to the partitioning of snow and rainfall, and to the timing of snowmelt, which will have important implications for water use and management. These changes also involve potentially important decadal and longer time-scale feedbacks to the climate system through temporal and spatial changes in soil moisture and runoff to the oceans (Walsh 1995). Freshwater fluxes from the snow cover into the marine environment may be important, as the total flux is probably of the same magnitude as desalinated ridging and rubble areas of sea ice (Prinsenberg 1988). In addition, there is an associated pulse of precipitated pollutants which accumulate over the Arctic winter in snowfall and are released into the ocean upon ablation of the sea-ice cover. Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. ... This article is about Earth as a planet. ... Missing main definition------ someone add if you know it please. ... The Colorado River from the bottom of Marble Canyon, in the Upper Grand Canyon Colorado River in the Grand Canyon from Desert View The Colorado River from Laughlin Horseshoe Bend is a horseshoe-shaped meander of the Colorado River located near the town of Page, Arizona The Colorado River is... Vegetation gives off heat, resulting in this circular snowmelt pattern. ... Run-off or runoff may refer to one of the following. ... A coral reef near the Hawaiian islands is an example of a complex marine ecosystem. ... It has been suggested that this article or section be merged with Feedback loop. ... This article or section does not cite its references or sources. ... Run-off or runoff may refer to one of the following. ... Animated map exhibiting the worlds oceanic waters. ... Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ...

Sea ice

Sea ice covers much of the polar oceans and forms by freezing of sea water. Satellite data since the early 1970s reveal considerable seasonal, regional, and interannual variability in the sea-ice covers of both hemispheres. Seasonally, sea-ice extent in the Southern Hemisphere varies by a factor of 5, from a minimum of 3-4 million km² in February to a maximum of 17-20 million km² in September (Zwally et al. 1983; Gloersen et al. 1992). The seasonal variation is much less in the Northern Hemisphere where the confined nature and high latitudes of the Arctic Ocean result in a much larger perennial ice cover, and the surrounding land limits the equatorward extent of wintertime ice. Thus, the seasonal variability in Northern Hemisphere ice extent varies by only a factor of 2, from a minimum of 7-9 million km² in September to a maximum of 14-16 million km² in March (Parkinson et al. 1987; Gloersen et al. 1992). An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ... For other uses, see Satellite (disambiguation). ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ... southern hemisphere highlighted in yellow (Antarctica not depicted). ... Northern hemisphere highlighted in yellow. ...

The ice cover exhibits much greater regional-scale interannual variability than it does hemispherical. For instance, in the region of the Seas of Okhotsk and Japan, maximum ice extent decreased from 1.3 million km² in 1983 to 0.85 million km² in 1984, a decrease of 35%, before rebounding the following year to 1.2 million km² (Gloersen et al. 1992). The regional fluctuations in both hemispheres are such that for any several-year period of the satellite record some regions exhibit decreasing ice coverage while others exhibit increasing ice cover (Parkinson 1995). The overall trend indicated in the passive microwave record from 1978 through mid-1995 shows that the extent of Arctic sea ice is decreasing 2.7% per decade (Johannessen et al. 1995). Subsequent work with the satellite passive-microwave data indicates that from late October 1978 through the end of 1996 the extent of Arctic sea ice decreased by 2.9% per decade while the extent of Antarctic sea ice increased by 1.3% per decade (Cavalieri et al. 1997). For other uses, see Satellite (disambiguation). ... NOAA Projected arctic changes Polar ice packs are large areas of pack ice formed from seawater in the Earths polar regions, known as polar ice caps: the Arctic ice pack (or Arctic ice cap) of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean, a part... The red line indicates the 10°C isotherm in July, commonly used to define the Arctic region border Satellite image of the Arctic surface The Arctic is the region around the Earths North Pole, opposite the Antarctic region around the South Pole. ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ... Greek &#7936;&#957;&#964;&#945;&#961;&#954;&#964;&#953;&#954;&#8057;&#962;, opposite the arctic) is a continent surrounding the Earths South Pole. ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ...

Lake ice and river ice

Ice forms on rivers and lakes in response to seasonal cooling. The sizes of the ice bodies involved are too small to exert other than localized climatic effects. However, the freeze-up/break-up processes respond to large-scale and local weather factors, such that considerable interannual variability exists in the dates of appearance and disappearance of the ice. Long series of lake-ice observations can serve as a proxy climate record, and the monitoring of freeze-up and break-up trends may provide a convenient integrated and seasonally specific index of climatic perturbations. Information on river-ice conditions is less useful as a climatic proxy because ice formation is strongly dependent on river-flow regime, which is affected by precipitation, snow melt, and watershed runoff as well as being subject to human interference that directly modifies channel flow, or that indirectly affects the runoff via land-use practices. This article is about water ice. ... For the Second World War frigate class, see River class frigate The Murray River in Australia A waterfall on the Ova da Fedoz, Switzerland A river is a large natural waterway. ... Lake Clearwater, Ontario, Canada A lake is a large body of water, usually fresh water, surrounded by land. ... Run-off or runoff may refer to one of the following. ...

Lake freeze-up depends on the heat storage in the lake and therefore on its depth, the rate and temperature of any inflow, and water-air energy fluxes. Information on lake depth is often unavailable, although some indication of the depth of shallow lakes in the Arctic can be obtained from airborne radar imagery during late winter (Sellman et al. 1975) and spaceborne optical imagery during summer (Duguay and Lafleur 1997). The timing of breakup is modified by snow depth on the ice as well as by ice thickness and freshwater inflow. For other uses, see Lake (disambiguation). ... The red line indicates the 10°C isotherm in July, commonly used to define the Arctic region border Satellite image of the Arctic surface The Arctic is the region around the Earths North Pole, opposite the Antarctic region around the South Pole. ...

Frozen ground and permafrost

Frozen ground (permafrost and seasonally frozen ground) occupies approximately 54 million km² of the exposed land areas of the Northern Hemisphere (Zhang et al., 2003) and therefore has the largest areal extent of any component of the cryosphere. Permafrost (perennially frozen ground) may occur where mean annual air temperatures (MAAT) are less than -1 or -2°C and is generally continuous where MAAT are less than -7°C. In addition, its extent and thickness are affected by ground moisture content, vegetation cover, winter snow depth, and aspect. The global extent of permafrost is still not completely known, but it underlies approximately 20% of Northern Hemisphere land areas. Thicknesses exceed 600 m along the Arctic coast of northeastern Siberia and Alaska, but, toward the margins, permafrost becomes thinner and horizontally discontinuous. The marginal zones will be more immediately subject to any melting caused by a warming trend. Most of the presently existing permafrost formed during previous colder conditions and is therefore relic. However, permafrost may form under present-day polar climates where glaciers retreat or land emergence exposes unfrozen ground. Washburn (1973) concluded that most continuous permafrost is in balance with the present climate at its upper surface, but changes at the base depend on the present climate and geothermal heat flow; in contrast, most discontinuous permafrost is probably unstable or “in such delicate equilibrium that the slightest climatic or surface change will have drastic disequilibrium effects” (Washburn 1973, p. 48). In geology, permafrost or permafrost soil is soil at or below the freezing point of water (0°C or 32°F) for two or more years. ... Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants, and is, by far, the most abundant biotic element of the biosphere. ... Northern hemisphere highlighted in yellow. ...

Under warming conditions, the increasing depth of the summer active layer has significant impacts on the hydrologic and geomorphic regimes. Thawing and retreat of permafrost have been reported in the upper Mackenzie Valley and along the southern margin of its occurrence in Manitoba, but such observations are not readily quantified and generalized. Based on average latitudinal gradients of air temperature, an average northward displacement of the southern permafrost boundary by 50-to-150 km could be expected, under equilibrium conditions, for a 1°C warming. Water covers 70% of the Earths surface. ... Surface of the Earth Geomorphology is the study of landforms, including their origin and evolution, and the processes that shape them. ... In geology, permafrost or permafrost soil is soil at or below the freezing point of water (0°C or 32°F) for two or more years. ... Motto: Gloriosus et Liber (Latin: Glorious and free) BC AB SK MB ON QC NB PE NS NL YT NT NU Capital Winnipeg Largest city Winnipeg Official languages English Government - Lieutenant-Governor John Harvard - Premier Gary Doer (NDP) Federal representation in Canadian Parliament - House seats 14 - Senate seats 6 Confederation... In geology, permafrost or permafrost soil is soil at or below the freezing point of water (0°C or 32°F) for two or more years. ...

Only a fraction of the permafrost zone consists of actual ground ice. The remainder (dry permafrost) is simply soil or rock at subfreezing temperatures. The ice volume is generally greatest in the uppermost permafrost layers and mainly comprises pore and segregated ice in Earth material. Measurements of bore-hole temperatures in permafrost can be used as indicators of net changes in temperature regime. Gold and Lachenbruch (1973) infer a 2-4°C warming over 75 to 100 years at Cape Thompson, Alaska, where the upper 25% of the 400-m thick permafrost is unstable with respect to an equilibrium profile of temperature with depth (for the present mean annual surface temperature of -5°C). Maritime influences may have biased this estimate, however. At Prudhoe Bay similar data imply a 1.8°C warming over the last 100 years (Lachenbruch et al. 1982). Further complications may be introduced by changes in snow-cover depths and the natural or artificial disturbance of the surface vegetation. This article is about Earth as a planet. ... Official language(s) None[1] Spoken language(s) English 85. ... In geology, permafrost or permafrost soil is soil at or below the freezing point of water (0°C or 32°F) for two or more years. ... An oceanic climate (also called marine west coast climate and maritime climate) is the climate typically found along the west coasts at the middle latitudes of all the worlds continents, and in southeastern Australia; similar climates are also found at high elevations within the tropics. ... Prudhoe Bay is a census-designated place located in North Slope Borough, Alaska. ...

The potential rates of permafrost thawing have been established by Osterkamp (1984) to be two centuries or less for 25-meter-thick permafrost in the discontinuous zone of interior Alaska, assuming warming from -0.4 to 0°C in 3-4 years, followed by a further 2.6°C rise. Although the response of permafrost (depth) to temperature change is typically a very slow process (Osterkamp 1984; Koster 1993), there is ample evidence for the fact that the active-layer thickness quickly responds to a temperature change (Kane et al. 1991). Whether, under a warming or cooling scenario, global climate change will have a significant effect on the duration of frost-free periods in both regions with seasonally- and perennially-frozen ground. Official language(s) None[1] Spoken language(s) English 85. ...

Glaciers and ice sheets

Ice sheets are the greatest potential source of global freshwater, holding approximately 77% of the global total. This corresponds to 80 m of world sea-level equivalent, with Antarctica accounting for 90% of this. Greenland accounts for most of the remaining 10%, with other ice bodies and glaciers accounting for less than 0.5% (Table 6.1). Because of their size in relation to annual rates of snow accumulation and melt, the residence time of water in ice sheets can extend to 100,000 or 1 million years. Consequently, any climatic perturbations produce slow responses, occurring over glacial and interglacial periods. Valley glaciers respond rapidly to climatic fluctuations with typical response times of 10-50 years (Oerlemans 1994). However, the response of individual glaciers may be asynchronous to the same climatic forcing because of differences in glacier length, elevation, slope, and speed of motion. Oerlemans (1994) provided evidence of coherent global retreat in glaciers which could be explained by a linear warming trend of 0.66°C per 100 years. An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square kilometers (12 million acres). ...

While glacier variations are likely to have minimal effects upon global climate, their recession may have contributed one third to one half of the observed 20th Century rise in sea level (Meier 1984; IPCC 1996). Furthermore, it is extremely likely that such extensive glacier recession as is currently observed in the Western Cordillera of North America (Pelto 1996), where runoff from glacierized basins is used for irrigation and hydropower, involves significant hydrological and ecosystem impacts. Effective water-resource planning and impact mitigation in such areas depends upon developing a sophisticated knowledge of the status of glacier ice and the mechanisms that cause it to change. Furthermore, a clear understanding of the mechanisms at work is crucial to interpreting the global-change signals that are contained in the time series of glacier mass-balance records. Global climate is a concept that has never been defined, but roughly speaking it is meant to express the average temperature, average precipitation, average intensity of winds and similar features of Earths atmosphere and the whole planets surface. ... Irrigation is the artificial application of water to the soil usually for assisting in growing crops. ... Undershot water wheels on the Orontes River in Hama, Syria Saint Anthony Falls Hydropower is the capture of the energy of moving water for some useful purpose. ... A coral reef near the Hawaiian islands is an example of a complex marine ecosystem. ...

Combined mass-balance estimates of the large ice sheets carry an uncertainty of about 20%. Studies based on estimated snowfall and mass output tend to indicate that the ice sheets are near balance or taking some water out of the oceans (Bentley and Giovinetto 1991). Marinebased studies (Jacobs et al. 1992) suggest sea-level rise from the Antarctic or rapid ice-shelf basal melting. Some authors (Paterson 1993; Alley 1997) have suggested that the difference between the observed rate of sea-level rise (roughly 2 mm/y) and the explained rate of sea-level rise from melting of mountain glaciers, thermal expansion of the ocean, etc. (roughly 1 mm/y or less) is similar to the modeled imbalance in the Antarctic (roughly 1 mm/y of sea-level rise; Huybrechts 1990), suggesting a contribution of sea-level rise from the Antarctic. Greek &#7936;&#957;&#964;&#945;&#961;&#954;&#964;&#953;&#954;&#8057;&#962;, opposite the arctic) is a continent surrounding the Earths South Pole. ...

Relationships between global climate and changes in ice extent are complex. The mass balance of land-based glaciers and ice sheets is determined by the accumulation of snow, mostly in winter, and warm-season ablation due primarily to net radiation and turbulent heat fluxes to melting ice and snow from warm-air advection (Munro 1990; Paterson 1993; Van den Broeke 1996). However, most of Antarctica never experiences surface melting (Van den Broeke and Bintanja 1995). Where ice masses terminate in the ocean, iceberg calving is the major contributor to mass loss. In this situation, the ice margin may extend out into deep water as a floating ice shelf, such as that in the Ross Sea. Despite the possibility that global warming could result in losses to the Greenland ice sheet being offset by gains to the Antarctic ice sheet (Ohmura et al. 1996), there is major concern about the possibility of a West Antarctic Ice Sheet collapse. The West Antarctic Ice Sheet is grounded on bedrock below sea level, and its collapse has the potential of raising the world sea level 6-7 m over a few hundred years. Ablation is defined as the removal of material from the surface of an object by vaporization, chipping, or other erosive processes. ... Animated map exhibiting the worlds oceanic waters. ... Map of Antarctica (click to enlarge) Ice in the Ross Sea, Antarctica The Ross Sea is a deep bay of the Southern Ocean in Antarctica between Victoria Land and Marie Byrd Land. ... Outline Map of Greenland with ice sheet depths. ... A satellite composite image of Antarctica The Antarctic ice sheet is the largest single mass of ice on Earth. ... The West Antarctic Ice Sheet (WAIS) blankets the continent of Antarctica west of the Transantarctic Mountains, covering the area called Lesser Antarctica. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. ...

Most of the discharge of the West Antarctic Ice Sheet is via the five major ice streams (faster flowing ice) entering the Ross Ice Shelf, the Rutford Ice Stream entering Ronne-Filchner shelf of the Weddell Sea, and the Pine Island Glacier entering the Amundsen Ice Shelf. Opinions differ as to the present mass balance of these systems (Bentley 1983, 1985), principally because of the limited data. The West Antarctic Ice Sheet is stable so long as the Ross Ice Shelf is constrained by drag along its lateral boundaries and pinned by local grounding. The West Antarctic Ice Sheet (WAIS) blankets the continent of Antarctica west of the Transantarctic Mountains, covering the area called Lesser Antarctica. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. ... Ross Ice Shelf in 1997. ... The Weddell Sea is part of the Southern Ocean. ... Pine Island Glacier (75°10′S 100°0′W) is a broad glacier flowing west-northwest along the south side of the Hudson Mountains into Pine Island Bay, Amundsen Sea. ... Ross Ice Shelf in 1997. ...

External links

• Global Outlook for Ice and Snow Assessment on the state and future of the Cryosphere, by the UN Environment Programme, June 2007
• Cryosphere overview map, from the UN Environment Programme
• Canadian Cryospheric Information Network
• State of the Canadian Cryosphere
• Near-real-time overview of global ice concentration and snow extent
• National Snow and Ice Data Center