The following outline is provided as an overview of and topical guide to water: Water – chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state (water vapor or steam). Under nomenclature used to name chemical compounds, Dihydrogen monoxide is the scientific name for water, though it is almost never used.
History The identification of water as a substance
Chemical properties and use
Properties of water – Physical and chemical properties of pure water Electrolysis of water – Electricity-induced chemical reaction Water of crystallization – Water molecules present inside crystals Dealkalization of water – Removal of alkalinity ions from water Drinking water quality standards – Quality parameters set for drinking water Portable water purification – Self-contained, easily transported units used to purify water from untreated sources Self-ionization of water – Autoprotolysis or exchange of a proton between two water molecules Water-in-water emulsion Water purification – Process of removing impurities from water Water treatment – Process that improves the quality of water Water (data page) – Chemical data page for water Hard water – Water that has a high mineral content Soft water – Water that has a low mineral content Water softening – Removing positive ions from hard water Water absorption Heavy water – Form of water Distilled water – Water purified by condensing it from steam Salinity – Proportion of salt dissolved in water Saline water – Water that contains a high concentration of dissolved salts Seawater – Water from a sea or an ocean Hydrate – Substance containing water or its constituent elements Boiling – Physical process
Physical properties
Properties of water – Physical and chemical properties of pure water Color of water – Water color in different conditions Water vapor – Gaseous phase of water Vapour pressure of water – Pressure exerted by molecules of water vapor in gaseous form Steam – Water in the gas phase Ice – Frozen water; the solid state of water Optical properties of water and ice Water quality – Assessment against standards for use Water (data page) – Chemical data page for water Mineral water – Drinking water from a mineral spring
Geography
Origin of water on Earth – Hypotheses for the possible sources of the water on Earth Evolution of water on Mars and Earth Extraterrestrial liquid water – Liquid water naturally occurring outside Earth Water on terrestrial planets of the Solar System Lunar water – Presence of water on the Moon Water on Mars – Study of past and present water on Mars List of extrasolar candidates for liquid water – Possible existence of liquid water beyond Earth Hydrosphere – Liquid water on a planet Hydrology – Science of the movement, distribution, and quality of water on Earth Water distribution on Earth Water cycle – Biogeochemical cycle for movement of water on Earth Groundwater – Water located beneath the ground surface Body of water – Any significant accumulation of water, generally on a planet's surface Salt water – Water that contains a high concentration of dissolved salts Seawater – Water from a sea or an ocean Ocean – Body of salt water covering most of Earth Sea – Large body of salt water Tide – Change in sea level due to gravity Brine – Concentrated solution of salt in water Brackish water – Water with salinity between freshwater and seawater Fresh water – Naturally occurring water with low amounts of dissolved salts Aquifer – Underground water-bearing rock River – Natural flowing freshwater stream Drainage – Removal of water from an area of land Drainage divide – Elevated terrain that separates neighbouring drainage basins Drainage basin – Land area where water converges to a common outlet Lake – Large inland body of relatively still water Glacier – Persistent body of ice that moves downhill under its own weight Geyser – Natural explosive eruption of hot water Spring – A point at which water emenges from an aquifer to the surface Waterfall – Point in a river or brook where water flows over a vertical drop List of waterfalls
Weather
Precipitation (meteorology) – Condensed water vapor that falls from cloudsPages displaying short descriptions of redirect targets Rain – Form of precipitation Freezing rain – Rain maintained at temperatures below freezing Drizzle – Light liquid precipitation Snow – Precipitation in the form of ice crystal flakes Snow pellets – Precipitation that forms when supercooled droplets of water freeze on a falling snowflakePages displaying short descriptions of redirect targets Snow grains – Form of precipitation Ice pellets – Precipitation consisting of small, translucent balls of ice Hail – Form of solid precipitation Ice crystals – Water ice in symmetrical shapesPages displaying short descriptions of redirect targets Dew – Droplets of water that form in the morning or evening Frost – Coating or deposit of ice Hoarfrost – Coating or deposit of icePages displaying short descriptions of redirect targets Atmospheric icing – Weather condition in which water droplets freeze onto objects they come in contact with Glaze ice – Coating of ice on objectsPages displaying short descriptions of redirect targets Cloud – Visible mass of particles suspended in the atmospheres Fog – Atmospheric phenomenon Mist – Phenomenon caused by small droplets of water suspended in air Spindrift – Spray blown from cresting waves in gales Flood – Water overflow submerging usually-dry land Wave – Dynamic disturbance in a medium or field Wind wave – Surface waves generated by wind on open water Tsunami – Series of water waves Drought – Period with less precipitation than normal
In nature and life
Origin of water on Earth – Hypotheses for the possible sources of the water on Earth Evolution of water on Mars and Earth Water intoxication – Potentially fatal overhydration Drinking water – Water safe for consumption Drowning – Respiratory impairment caused by submersion in liquid Dehydration – Deficit of total body water
Marine and aquatic life Underwater – Aquatic or submarine environmentPages displaying short descriptions of redirect targets Marine biology – Scientific study of ocean life Marine life – Organisms that live in salt water Hydrobiology – Science of life and life processes in water Aquatic ecosystem – Ecosystem in a body of water
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