Water
hideWater is a ubiquitous chemical substance, composed of hydrogen and oxygen, that is essential for the survival of many known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Other water is trapped in ice caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life on land.
Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea. Over land, evaporation and transpiration contribute to the precipitation over land.
Clean, fresh drinking water is essential to human and other lifeforms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.
For more information about Water, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with liquid water
3 Questions: Sara Seager on searching for Earth-like planets
Nov 23, 2009 |
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(PhysOrg.com) -- MIT planetary scientist Sara Seager has been studying exoplanets — planets circling stars other than the sun — for many years.
Taking a Bite of Antarctic Ice
Space & Earth / Space Exploration
Nov 16, 2009 |
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Scientists with NASA’s IceBite project are heading this week for University Valley, a hanging valley perched more than 1600 feet (more than 1 mile) above sea level in Antarctica’s McMurdo Dry Valleys. Their ...
A Tale of Planetary Woe (w/ Video)
Space & Earth / Space Exploration
Nov 11, 2009 |
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Once upon a time — roughly four billion years ago — Mars was warm and wet, much like Earth. Liquid water flowed on the Martian surface in long rivers that emptied into shallow seas. A thick atmosphere blanketed ...
Jupiter's Moon Europa Has Enough Oxygen For Life
Space & Earth / Earth Sciences
Oct 16, 2009 |
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New research suggests that there is plenty of oxygen available in the subsurface ocean of Europa to support oxygen-based metabolic processes for life similar to that on Earth. In fact, there may be enough ...
Hot Debate over Icy Moon
Space & Earth / Space Exploration
Oct 08, 2009 |
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The recent discovery of plumes containing water vapor erupting from the south pole of the frigid Saturnian moon Enceladus set off a firestorm of debate.
It's a grind to make Mars red
Space & Earth / Space Exploration
Sep 18, 2009 |
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(PhysOrg.com) -- The widespread idea that Mars is red due to rocks being rusted by the water that once flooded the red planet may be wrong. Recent laboratory studies show that the red dust may be formed by ...
Kepler and the Search for Life in Our Galaxy
Sep 15, 2009 |
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(PhysOrg.com) -- There are so many stars in our galaxy that even if planets with complex life (animals and plants) are rare - say one for every billion stars - there could still be dozens here in the Milky ...
Will Kepler find habitable moons?
Sep 03, 2009 |
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(PhysOrg.com) -- Since the launch of the NASA Kepler Mission earlier this year, astronomers have been keenly awaiting the first detection of an Earth-like planet around another star. Now, in an echo of science ...
Evidence of liquid water in comets reveals possible origin of life
Space & Earth / Space Exploration
Jul 30, 2009 |
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Comets contained vast oceans of liquid water in their interiors during the first million years of their formation, a new study claims.
Evidence for ocean on Enceladus: Tiny Saturn Moon Could Be Targeted in Search for Extraterrestrial Life
Space & Earth / Space Exploration
Jul 22, 2009 |
4.6 / 5 (16) |
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(PhysOrg.com) -- Plumes spewing from a tiny moon of Saturn - a moon roughly the width of Arizona - are filled with molecules that suggest that the moon, Enceladus, is likely another place in the solar system ...
Why Does Water Expand When it Cools? A New Explanation
Jul 17, 2009 |
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(PhysOrg.com) -- Most of us, when we take our first science classes, learn that when things cool down, they shrink. (When they heat up, we learn, they usually expand.) However, water seems to be the exception ...
Volcanic activity on Mars could offer clues to planet's history
Space & Earth / Space Exploration
Jul 13, 2009 |
4 / 5 (4) |
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From literature to the Big Screen, the fascination with the planet Mars has taken many forms. In the geology department at Mercyhurst College, that attraction currently surrounds three of the planet's oldest ...
Many characteristics of Mars, including ice, are similar to Earth
Space & Earth / Space Exploration
Jul 02, 2009 |
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Mars gets as far as 250 million miles away, but many parts of it closely resemble places on Earth, including its landscape, history of water, soil and even its weather, says a Texas A&M University researcher ...
Scientists Observe Liquid Water Below Freezing
Jun 24, 2009 |
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(PhysOrg.com) -- Below 0 °C, water turns to ice. But beyond that, or below about -75 °C, the ice may turn back into liquid water. While scientists have previously predicted this phase transition with computer ...
'Cold' Mars Could Have Harbored Liquid Water
Space & Earth / Space Exploration
Jun 01, 2009 |
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(PhysOrg.com) -- A new NASA study provides further evidence that Martian minerals dissolved in water could have kept that water from freezing, even on a cold, early Mars.
