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Meltwater
 
 
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Meltwater is the water released by the melting
Melting

Melting is a process that results in the phase change of a substance from a solid to a liquid. The internal energy of a solid substance is increased to a specific temperature at which it changes to the liquid phase....
 of snow
Snow

Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. The process of this precipitation is called snowfall....
 or ice
Ice

Ice is a solid phases of matter, usually crystalline solid, of a non-metallic substance that is liquid or gas at room temperature, such as ammonia ice or methane ice....
, including glacial ice and ice shelf
Ice shelf

An ice shelf is a thick, floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface....
s over oceans. Meltwater is often found in the ablation zone
Ablation zone

On a glacier, the ablation zone, zone of ablation or zone of wastage is the area in which annual loss of snow through melting, evaporation, iceberg calving and sublimation exceeds annual gain of snow and ice on the surface....
 of glaciers, where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions
Volcanic Eruptions

'Volcanic Eruptions' is the name of Crispin Glover's film production company. It has released two films to date, What Is It? and its sequel, It Is Fine....
, in a similar way in which the more dangerous lahar
Lahar

A lahar is a type of mudflow or landslide composed of pyroclastic material and water that flows down from a volcano, typically along a river valley....
s form.

When meltwater pools on the surface rather than flowing, it forms melt ponds. As the weather gets colder meltwater will often re-freeze.






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Encyclopedia


Meltwater is the water released by the melting
Melting

Melting is a process that results in the phase change of a substance from a solid to a liquid. The internal energy of a solid substance is increased to a specific temperature at which it changes to the liquid phase....
 of snow
Snow

Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. The process of this precipitation is called snowfall....
 or ice
Ice

Ice is a solid phases of matter, usually crystalline solid, of a non-metallic substance that is liquid or gas at room temperature, such as ammonia ice or methane ice....
, including glacial ice and ice shelf
Ice shelf

An ice shelf is a thick, floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface....
s over oceans. Meltwater is often found in the ablation zone
Ablation zone

On a glacier, the ablation zone, zone of ablation or zone of wastage is the area in which annual loss of snow through melting, evaporation, iceberg calving and sublimation exceeds annual gain of snow and ice on the surface....
 of glaciers, where the rate of snow cover is reducing. Meltwater can be produced during volcanic eruptions
Volcanic Eruptions

'Volcanic Eruptions' is the name of Crispin Glover's film production company. It has released two films to date, What Is It? and its sequel, It Is Fine....
, in a similar way in which the more dangerous lahar
Lahar

A lahar is a type of mudflow or landslide composed of pyroclastic material and water that flows down from a volcano, typically along a river valley....
s form.

When meltwater pools on the surface rather than flowing, it forms melt ponds. As the weather gets colder meltwater will often re-freeze. Meltwater can collect or melt under the ice's surface. These pools of water, known as subglacial lake
Subglacial lake

A subglacial lake is a lake under a glacier, typically an ice cap or ice sheet. There are many such lakes, with Lake Vostok in Antarctica being by far the largest known at present....
s can form due to geothermal heat and friction.

Water source

Meltwater provides drinking water
Drinking water

Drinking water is water that is of sufficiently high quality so that it can be consumed or utilized without risk of immediate or long term harm....
 for a large proportion of the world's population, as well as providing water for irrigation
Irrigation

Irrigation is an artificial application of water to the soil usually for assisting in growing crops. In crop production it is mainly used in dry areas and in periods of rainfall shortfalls, but also to protect plants against frost....
 and hydroelectric plants
Hydroelectricity

Hydroelectricity is electricity generated by hydropower, i.e., the production of power through use of the gravitational force of falling or flowing water....
. Some cities around the world have large lakes that collect snow melt to supplement water supply. Cities that source water from meltwater include Canberra
Canberra

Canberra is the List of Australian capital cities of Australia. With a population of over 340,000, it is Australia's largest inland city and the eighth largest Australian city overall....
, Los Angeles
Los Ángeles

Los ?ngeles is the Capital of the Biob?o Province, in the municipality of the same name, in Regions of Chile VIII , in the center-south of Chile....
, Las Vegas
Las Vegas, Nevada

Las Vegas is the most populous city in the U.S. state of Nevada, the seat of Clark County, Nevada, and an internationally renowned major resort city for gambling, shopping, and entertainment....
 amongst others.

Glacial meltwater

Fryxellsee Opt
Glacial meltwater comes from glaciers that have receded over time. Often, there will be rivers flowing through glaciers into lakes. These brilliantly blue lakes get their color from "rock flour
Rock flour

Rock flour, or glacial flour, consists of particle size particles of rock, generated by Glacier#Glacial erosion or by artificial grinding to a similar size....
", sediment
Sediment

Sediment is any particulate matter that can be sediment transport by fluid dynamics, and which eventually is deposited.Sediments are most often transported by water transported by wind and glaciers....
 that has been transported through the rivers to the lakes. This sediment comes from rocks grinding together underneath the glacier. The fine powder
Powder (substance)

A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material....
 is then suspended in the water and refracts sunlight
Sunlight

Sunlight, in the broad sense, is the total spectroscopy of the electromagnetic radiation given off by the Sun. On Earth, sunlight is Filter ed through the Earth's atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon....
 therefor giving the milky turquoise appearance.

Meltwater also acts as a lubricant
Lubricant

A lubricant is a substance introduced between two moving surfaces to reduce the friction between them, improving efficiency and reducing wear....
 in the basal sliding
Basal sliding

Basal Sliding is the act of a glacier sliding over the bed before it due to meltwater under the ice acting as a lubricant. This movement very much depends on the temperature of the area, the slope of the glacier, the bed's sediment size, the amount of meltwater from the glacier, and the glacier's size....
 of glaciers. Using GPS measurements to study ice flow has revealed that glacial movement
Glacial motion

Glacial motion is the motion of glaciers, which can be likened to rivers of ice. It has played an important role in sculpting many landscapes....
 is greatest in summer when the meltwater levels are hightest.

Rapid changes

Meltwater can be an indication of abrupt climate change
Abrupt climate change

Abrupt climate change refers to an event where significant shift in climate occurs within a geologically short timescale. The archetypical event of this kind is the end of the Younger Dryas....
. An instance of a large meltwater body is the case of the region of a tributary of Bindschadler Ice Stream, West Antarctica
West Antarctica

West Antarctica, or Lesser Antarctica is one of the two major regions of Antarctica, lying on the Pacific Ocean side of the Transantarctic Mountains and comprising Marie Byrd Land, Ellsworth Land, and the Antarctic Peninsula....
 where rapid vertical motion of the ice sheet surface has suggested shifting of a subglacial water body.

It can also destabilize glacial lakes leading to sudden flood
Flood

A flood is an overflow of an expanse of water that submerges land, a deluge. In the sense of "flowing water", the word may also be applied to the inflow of the tide....
s, and destabilize snowpack
Snow

Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. The process of this precipitation is called snowfall....
 causing avalanche
Avalanche

An avalanche is a rapid flow of snow down a slope, from either natural triggers or human activity. Typically occurring in mountainous terrain, an avalanche can mix air and water with the descending snow....
s. Dammed glacial meltwater from a moraine-dammed lake that is released suddenly can resulted in the floods that created the granite chasms in Purgatory Chasm State Reservation
Purgatory Chasm State Reservation

Purgatory Chasm State Reservation is a state park located in Sutton, Massachusetts. The park, managed by the Department of Conservation and Recreation , is notable for its long, deep chasm of granite bedrock featuring abrupt precipices and boulder caves in which ice lingers into the early summer....
.

Global warming

In a report published in June 2007, the United Nations Environment Programme
United Nations Environment Programme

The UN Environment Programme coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and encourages sustainable development through sound environmental practices....
 estimated that global warming
Global warming

Global warming is the increase in the Instrumental temperature record of the Earth's near-surface air and the oceans since the mid-twentieth century and its projected continuation....
 could lead to 40% of the world population
World population

The world population is the total number of living humans on Earth at a given time. As of March 2009, the world's population is estimated to be about 6.76 1,000,000,000 ....
 being affected by the loss of glaciers, snow and the associated meltwater in Asia
Asia

Asia is the world's largest and most populous continent. It covers 8.6% of the Earth's total surface area and, with over 4 billion people, it contains more than 60% of the world's current human population....
. Historically Meltwater pulse 1A
Meltwater pulse 1A

Meltwater pulse 1A was a period of rapid Holocene glacial retreat that took place 14.7-14.2 thousand years ago.. During this pulse the sea level rose by about 25 m in some parts of the northern hemisphere, over a period of less than 500 years....
 was a prominent feature of the last deglaciation and took place 14.7-14.2 thousand years ago.

See also

  • Groundwater
    Groundwater

    Groundwater is water located beneath the ground surface in soil porosity spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water....
  • Moulin (geology)
    Moulin (geology)

    A moulin or glacier mill is a narrow, tubular chute, hole or crevasse through which water enters a glacier from the surface. They can be up to 10 meters wide and are typically found at a flat area of a glacier in a region of transverse crevasses....
  • Surface water
    Surface water

    Water collecting on the ground or in a stream, river, lake, wetland, or ocean is called surface water, as opposed to groundwater or atmospheric water....


External links



In the media

  • June 4, 2007, BBC: