The multiple arches of thePont du Gard inRoman Gaul (modern-day southernFrance). The upper tier encloses an aqueduct that carried water toNimes in Roman times; its lower tier was expanded in the 1740s to carry a wide road across the river.
Water is aninorganic compound with thechemical formulaH2O. It is a transparent, tasteless, odorless, andnearly colorlesschemical substance. It is the main constituent of Earth'shydrosphere and thefluids of all known living organisms, in which it acts as asolvent. Water, being apolar molecule, undergoes strong intermolecularhydrogen bonding which is a large contributor to its physical and chemical properties. It is vital for all known forms of life, despite not providingfood energy or being an organicmicronutrient. Due to its presence in all organisms, its chemical stability, its worldwide abundance, and its strong polarity relative to its small molecular size, water is often referred to as the "universal solvent".
Because Earth's environment is relatively close to water'striple point, water exists on Earth as a solid, a liquid, and a gas. It formsprecipitation in the form of rain andaerosols in the form offog. Clouds consist of suspended droplets of water andice, its solid state. When finely divided,crystalline ice may precipitate in the form of snow. The gaseous state of water issteam orwater vapor.
Reverse osmosis desalination plant in Barcelona, Spain
Desalination is a process that removes mineral components fromsaline water. More generally, desalination is the removal of salts and minerals from a substance. One example issoil desalination. This is important for agriculture. It is possible to desalinate saltwater, especiallysea water, to produce water for human consumption or irrigation, producingbrine as a by-product. Many seagoing ships andsubmarines use desalination. Modern interest in desalination mostly focuses on cost-effective provision offresh water for human use. Along with recycledwastewater, it is one of the fewwater resources independent of rainfall.
Due to its energy consumption, desalinating sea water is generally more costly than fresh water fromsurface water orgroundwater,water recycling andwater conservation; however, these alternatives are not always available and depletion of reserves is a critical problem worldwide. Desalination processes are using either thermal methods (in the case ofdistillation) or membrane-based methods (e.g. in the case ofreverse osmosis). (Full article...)
The head of animpact sprinkler, a type ofirrigation sprinkler in which the sprinkler head, driven in a circular motion by the force of the outgoing water, pivots on abearing on top of itsthreaded attachment nut. Invented in 1935 by Orton Englehardt, it quickly found widespread use.
Image 2Afire hydrant inAlkmaar, 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.
Plate XIX of "Studies among theSnow Crystals ... " byWilson 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 abellows camera he had attached to amicroscope. 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 ofice and naturalwater formations includingclouds andfog. He was the firstAmerican to recordraindrop sizes and was one of the firstcloud physicists.
Aniceberg is a large piece of freshwater ice that has broken off aglacier or anice 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 wasB-15, which split from theRoss 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 theArctic Ocean north ofSvalbard.
Image 5Waterfall Shypit (height 14 m), Mizhhiria Raion, Zakarpattia Oblast of western Ukraine
Rain is an oil-on-canvas painting by Dutch painterVincent van Gogh, part ofThe Wheat Field, a series that he executed in 1889 while a voluntary patient in theSaint-Paul asylum nearSaint-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 ofJapanese 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 thePhiladelphia Museum of Art.
When a liquiddrop 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, higherWeber 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 example ofguttation, the appearance of drops ofxylem sap on the tips or edges of leaves of somevascular plants, on anEquisetum. At night,transpiration usually does not occur because most plants have theirstomata closed. When there is a highsoil moisture level, water will enter plant roots, because thewater potential of the roots is lower than in the soil solution. The water will accumulate in the plant creating a slightroot pressure. The root pressure forces some water to exude through specialleaf tip or edge structures,hydathodes, forming drops. Guttation is not to be confused withdew, whichcondenses from the atmosphere onto the plant surface.
Ananimated image showing the long-termmean monthlyprecipitation around the world. Precipitation occurs when a local portion of theatmosphere becomes saturated withwater vapor andcondenses, forming rain drops or ice crystals within acloud via collision that then fall to the surface, except forvirga, whichevaporates while in the air.
Morningmist onLake Mapourika, a lake on theWest Coast ofNew Zealand'sSouth Island. It is the largest of the west coast lakes, aglacier formation from the lastice age. It is filled with fresh rain water which runs through the surrounding forest floor, collectingtannins and giving it its dark colour.
TheHaditha Dam is anearth-filled dam in Iraq, holding back the waters of theEuphrates to createLake Qadisiyah. The area aroundHaditha is very arid, with ahot desert climate; the annual precipitation is about 127 millimetres (5 in), mainly occurring during the winter. This photograph, taken from theInternational 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 associatedhydroelectric 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 forirrigation.
A side-by-side comparison of theAral Sea in 1989 and 2008, showing its severe shrinkage owing to poorwater resource management. The Aral Sea was once thefourth-largest lake in the world. However, the rivers that fed it were diverted bySoviet-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 poorenvironmental resource management.
Image 21A view of the Rosoki River in the eponymous village, Macedonia
Image 2Poverty 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, poorsanitation andhygiene. (fromDrinking water)
Image 3World map forSDG 6 Indicator 6.1.1 in 2022: "Proportion of population using safely managed drinking water services" (fromDrinking water)
Image 5A diagram illustrating capillary action in plants, showing the roles of cohesion and adhesion in the upward movement of water through the xylem.[1] (fromProperties of water)
Image 7Rain falling over adrainage basin inScotland. Understanding the cycling of water into, through, and out of catchments is a key element of hydrology. (fromHydrology)
Image 8Building a map of groundwater contours (fromHydrology)
Image 9Total renewable water resources per capita in 2020 (fromDrinking water)
Image 13Density of ice and water as a function of temperature (fromProperties of water)
Image 14Thispaper 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. (fromProperties of water)
Image 15Example for physical and chemical parameters measured in drinking water samples in Kenya and Ethiopia as part of asystematic review of published literature (fromDrinking water)
Image 16Diagram of water well types (fromDrinking water)
Image 17Temperature distribution in a lake in summer and winter (fromProperties of water)
Image 22Temperature dependence of the surface tension of pure water (fromProperties of water)
Image 23Estimates of changes in water storage around theTigris andEuphrates Rivers, measured by NASA'sGRACE 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. (fromHydrology)
Image 25The solid/liquid/vapor triple point of liquid water,ice Ih and water vapor in the lower left portion of a water phase diagram. (fromProperties of water)
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