Robots activated by water may be the next frontier

New research from the laboratory of Ozgur Sahin, associate professor of biological sciences and physics at Columbia University, shows that materials can be fabricated to create soft actuators—devices that convert energy ...

Researchers examine the age of groundwater in Egyptian aquifers

Most of the water used by people in Egypt comes from the Nile River, which originates from precipitation over mountainous areas in the Ethiopian highlands. In areas far from the Nile River Valley, however, where water is ...

What makes a place a home?

Invasive lionfish (Pterois volitans and P. miles) are now ubiquitous throughout the Caribbean and Western Atlantic on both shallow and deep reefs. While many invasive species disrupt natural ecosystems by spreading disease ...

New lidar instruments peer skyward for clues on weather and climate

Researchers have developed a set of diode-based lidar instruments that could help fill important gaps in meteorological observations and fuel a leap in understanding, modeling and predicting weather and climate. The instruments ...

Formation of the moon brought water to Earth

The Earth is unique in our solar system: It is the only terrestrial planet with a large amount of water and a relatively large moon, which stabilizes the Earth's axis. Both were essential for Earth to develop life. Planetologists ...

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Water

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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