The multiple arches of the Pont du Gard in Roman Gaul (modern-day southern France). The upper tier encloses an aqueduct that carried water to Nimes in Roman times; its lower tier was expanded in the 1740s to carry a wide road across the river.
Because Earth's environment is relatively close to water's triple point, water exists on Earth as a solid, a liquid, and a gas. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor.
The origin of water on Earth is the subject of a body of research in the fields of planetary science, astronomy, and astrobiology. Earth is unique among the rocky planets in the Solar System in having oceans of liquid water on its surface. Liquid water, which is necessary for all known forms of life, continues to exist on the surface of Earth because the planet is at a far enough distance (known as the habitable zone) from the Sun that it does not lose its water, but not so far that low temperatures cause all water on the planet to freeze.
It was long thought that Earth's water did not originate from the planet's region of the protoplanetary disk. Instead, it was hypothesized water and other volatiles must have been delivered to Earth from the outer Solar System later in its history. Recent research, however, indicates that hydrogen inside the Earth played a role in the formation of the ocean. The two ideas are not mutually exclusive, as there is also evidence that water was delivered to Earth by impacts from icy planetesimals similar in composition to asteroids in the outer edges of the asteroid belt. (Full article...)
Rain is an oil-on-canvas painting by Dutch painter Vincent van Gogh, part of The Wheat Field, a series that he executed in 1889 while a voluntary patient in the Saint-Paul asylum near Saint-Rémy-de-Provence, France. Through his cell window on the upper floor, he could see an enclosed wheat field, and he made about a dozen paintings of it over the changing seasons. In this work, he represented falling rain with diagonal lines of paint. The style is reminiscent of Japanese prints, but the effect is stylistically personal to Van Gogh. Seen through his rain-splattered window, he shows its bleak aspect in November, with grey clouds overhead and the wheat already harvested. The painting is now in the collection of the Philadelphia Museum of Art.
Image 2A view of the Rosoki River in the eponymous village, Macedonia
The Haditha Dam is an earth-filled dam in Iraq, holding back the waters of the Euphrates to create Lake Qadisiyah. The area around Haditha is very arid, with a hot desert climate; the annual precipitation is about 127 millimetres (5 in), mainly occurring during the winter. This photograph, taken from the International Space Station in November 2015, shows the reservoir at a low water level, surrounded by an expanse of dry lakebed; the Haditha Dam is visible near the top of the image. Lake Qadisiyah has a maximum water-storage capacity of 8.3 cubic kilometres (2.0 cu mi) and a maximum surface area of 500 square kilometres (190 sq mi). The associated hydroelectric power station is capable of generating 660 megawatts of electricity, and outlets at the foot of the dam can discharge 3,000 cubic metres (110,000 cu ft) of water per second for irrigation.
The head of an impact sprinkler, a type of irrigation sprinkler in which the sprinkler head, driven in a circular motion by the force of the outgoing water, pivots on a bearing on top of its threaded attachment nut. Invented in 1935 by Orton Englehardt, it quickly found widespread use.
An animated image showing the long-term mean monthly precipitation around the world. Precipitation occurs when a local portion of the atmosphere becomes saturated with water vapor and condenses, forming rain drops or ice crystals within a cloud via collision that then fall to the surface, except for virga, which evaporates while in the air.
Image 6Waterfall Shypit (height 14 m), Mizhhiria Raion, Zakarpattia Oblast of western Ukraine
An example of guttation, the appearance of drops of xylem sap on the tips or edges of leaves of some vascular plants, on an Equisetum. At night, transpiration usually does not occur because most plants have their stomata closed. When there is a high soil moisture level, water will enter plant roots, because the water potential of the roots is lower than in the soil solution. The water will accumulate in the plant creating a slight root pressure. The root pressure forces some water to exude through special leaf tip or edge structures, hydathodes, forming drops. Guttation is not to be confused with dew, which condenses from the atmosphere onto the plant surface.
A side-by-side comparison of the Aral Sea in 1989 and 2008, showing its severe shrinkage owing to poor water resource management. The Aral Sea was once the fourth-largest lake in the world. However, the rivers that fed it were diverted by Soviet-era irrigation projects. It had shrunk to 10% of its former size by 2007, and is still shrinking. The near-loss of the Aral Sea, which is now in Kazakhstan and Uzbekistan, has been considered one of the planet's most disastrous examples of poor environmental resource management.
Plate XIX of "Studies among the Snow Crystals ... " by Wilson Bentley (1902), the first person known to photograph snowflakes. He did so by catching an individual snowflake on a blackboard, rushing it onto some black velvet, which he would then photograph using a bellows camera he had attached to a microscope. His first photograph of a snowflake was on January 15, 1885 and he would capture over 5000 images of crystals in his lifetime. Bentley also photographed all forms of ice and natural water formations including clouds and fog. He was the first American to record raindrop sizes and was one of the first cloud physicists.
When a liquid drop impacts the surface of a liquid reservoir it can float, bounce, coalesce with the reservoir, or splash. A floating drop remains on the surface for several seconds. Drop bouncing can occur on perturbed liquid surfaces. If the drop is able to rupture the thin film of gas which separates it from the liquid reservoir, it can coalesce. Additionally, higher Weber number drop impacts produce splashing. In the splashing regime, the impacting drop creates a crater in the fluid surface, followed by a crown around the crater. Finally, a central jet, called the "Rayleigh jet" or "Worthington jet", protrudes from the center of the crater. If the impact energy is high enough, the jet rises to the point where it pinches off, sending one or more droplets upward out of the surface.
An iceberg is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in the open sea. Because the sea around this iceberg is so calm, the underwater portion is visible through the clear water. The largest iceberg ever detected was B-15, which split from the Ross Ice Shelf in Antarctica in 2000, and had a flat top; it had a surface area of 11,000 km2 (4,200 sq mi) and broke into several pieces in 2002 and 2003. This picture depicts an irregularly shaped iceberg with a rounded top, calved from a glacier in the Arctic and photographed in the Arctic Ocean north of Svalbard.
Morning mist on Lake Mapourika, a lake on the West Coast of New Zealand's South Island. It is the largest of the west coast lakes, a glacier formation from the last ice age. It is filled with fresh rain water which runs through the surrounding forest floor, collecting tannins and giving it its dark colour.
Image 21A fire hydrant in Alkmaar, the Netherlands. Fire hydrants are a source of water provided by most metropolitan communities to enable firefighters to tap into the municipal water supply to assist in extinguishing a fire.
The following are images from various water-related articles on Wikipedia.
Image 1Poverty often leads to unhygienic living conditions, as in this community in the Indian Himalayas. Such conditions promote contraction of diarrheal diseases, as a result of contaminated drinking water, poor sanitation and hygiene. (from Drinking water)
Image 12Example for physical and chemical parameters measured in drinking water samples in Kenya and Ethiopia as part of a systematic review of published literature. (from Drinking water)
Image 20Heat of vaporization of water from melting to critical temperature (from Properties of water)
Image 21Estimates of changes in water storage around the Tigris and Euphrates Rivers, measured by NASA's GRACE satellites. The satellites measure tiny changes in gravitational acceleration, which can then be processed to reveal movement of water due to changes in its total mass. (from Hydrology)
Image 23This paper clip is under the water level, which has risen gently and smoothly. Surface tension prevents the clip from submerging and the water from overflowing the glass edges. (from Properties of water)
Image 24Temperature dependence of the surface tension of pure water (from Properties of water)
Image 26Rain over a Scottish catchment. Understanding the cycling of water into, through, and out of catchments is a key element of hydrology. (from Hydrology)
Image 27Mortality rate attributable to unsafe water, sanitation, and hygiene (WASH). (from Drinking water)
Image 28The solid/liquid/vapor triple point of liquid water, ice Ih and water vapor in the lower left portion of a water phase diagram. (from Properties of water)
Image 29Total renewable water resources per capita in 2020 (from Drinking water)
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