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Tetrahedra may explain water's uniqueness

Researchers at the Institute of Industrial Science at the University of Tokyo sifted through experimental data to probe the possibility that supercooled water has a liquid-to-liquid phase transition between disordered and ...

Ants adapt tool use to avoid drowning

Researchers have observed black imported fire ants using sand to draw liquid food out of containers, when faced with the risk of drowning. This is the first time this sophisticated tool use has been reported in animals. These ...

Could life exist deep underground on Mars?

Recent science missions and results are bringing the search for life closer to home, and scientists at the Center for Astrophysics | Harvard & Smithsonian (CfA) and the Florida Institute of Technology (FIT) may have figured ...

The four most promising worlds for alien life in the solar system

The Earth's biosphere contains all the known ingredients necessary for life as we know it. Broadly speaking these are: liquid water, at least one source of energy, and an inventory of biologically useful elements and molecules.

AI used to show how hydrogen becomes a metal inside giant planets

Dense metallic hydrogen—a phase of hydrogen which behaves like an electrical conductor—makes up the interior of giant planets, but it is difficult to study and poorly understood. By combining artificial intelligence and ...

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Water 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.

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