Pontic Steppe
72-594: Water is an inorganic compound with the chemical formula H 2 O . It is a transparent, tasteless, odorless, and nearly colorless chemical substance . It is the main constituent of Earth 's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent ). It is vital for all known forms of life , despite not providing food energy or organic micronutrients . Its chemical formula, H 2 O , indicates that each of its molecules contains one oxygen and two hydrogen atoms , connected by covalent bonds . The hydrogen atoms are attached to
144-535: A French Jesuit who spent most of his life in India, had specifically demonstrated the analogy between Sanskrit and European languages. According to current academic consensus, Jones's famous work of 1786 was less accurate than his predecessors', as he erroneously included Egyptian , Japanese and Chinese in the Indo-European languages, while omitting Hindi . In 1818, Danish linguist Rasmus Christian Rask elaborated
216-659: A PIE homeland, the Kurgan and Anatolian hypotheses are the ones most widely accepted, and also the ones most debated against each other. Following the publication of several studies on ancient DNA in 2015, Colin Renfrew, the original author and proponent of the Anatolian hypothesis, has accepted the reality of migrations of populations speaking one or several Indo-European languages from the Pontic steppe towards Northwestern Europe. The table lists
288-436: A chemical as inorganic does not necessarily mean that it cannot occur within living things. Friedrich Wöhler 's conversion of ammonium cyanate into urea in 1828 is often cited as the starting point of modern organic chemistry . In Wöhler's era, there was widespread belief that organic compounds were characterized by a vital spirit . In the absence of vitalism, the distinction between inorganic and organic chemistry
360-544: A conventional mark of reconstructed words, such as * wódr̥ , * ḱwn̥tós , or * tréyes ; these forms are the reconstructed ancestors of the modern English words water , hound , and three , respectively. No direct evidence of PIE exists; scholars have reconstructed PIE from its present-day descendants using the comparative method . For example, compare the pairs of words in Italian and English: piede and foot , padre and father , pesce and fish . Since there
432-453: A detailed, though conservative, overview of the lexical knowledge accumulated by 1959. Jerzy Kuryłowicz's 1956 Apophonie gave a better understanding of Indo-European ablaut . From the 1960s, knowledge of Anatolian became robust enough to establish its relationship to PIE. Scholars have proposed multiple hypotheses about when, where, and by whom PIE was spoken. The Kurgan hypothesis , first put forward in 1956 by Marija Gimbutas , has become
504-606: A language. From the 1870s, the Neogrammarians proposed that sound laws have no exceptions, as illustrated by Verner's law , published in 1876, which resolved apparent exceptions to Grimm's law by exploring the role of accent (stress) in language change. August Schleicher 's A Compendium of the Comparative Grammar of the Indo-European, Sanskrit, Greek and Latin Languages (1874–77) represented an early attempt to reconstruct
576-481: A large amount of sediment transport that occurs on the surface of the earth. Deposition of transported sediment forms many types of sedimentary rocks , which make up the geologic record of Earth history . The water cycle (known scientifically as the hydrologic cycle) is the continuous exchange of water within the hydrosphere , between the atmosphere , soil water, surface water , groundwater, and plants. Water moves perpetually through each of these regions in
648-485: A pressure of 611.657 pascals (0.00604 atm; 0.0887 psi); it is the lowest pressure at which liquid water can exist. Until 2019 , the triple point was used to define the Kelvin temperature scale . The water/vapor phase curve terminates at 647.096 K (373.946 °C; 705.103 °F) and 22.064 megapascals (3,200.1 psi; 217.75 atm). This is known as the critical point . At higher temperatures and pressures
720-475: A property that is exploited by cetaceans and humans for communication and environment sensing ( sonar ). Metallic elements which are more electropositive than hydrogen, particularly the alkali metals and alkaline earth metals such as lithium , sodium , calcium , potassium and cesium displace hydrogen from water, forming hydroxides and releasing hydrogen. At high temperatures, carbon reacts with steam to form carbon monoxide and hydrogen. Hydrology
792-433: A structure of rigid oxygen atoms in which hydrogen atoms flowed freely. When sandwiched between layers of graphene , ice forms a square lattice. The details of the chemical nature of liquid water are not well understood; some theories suggest that its unusual behavior is due to the existence of two liquid states. Pure water is usually described as tasteless and odorless, although humans have specific sensors that can feel
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#1732844875699864-597: A thousand years. According to the prevailing Kurgan hypothesis , the original homeland of the Proto-Indo-Europeans may have been in the Pontic–Caspian steppe of eastern Europe. The linguistic reconstruction of PIE has provided insight into the pastoral culture and patriarchal religion of its speakers. As speakers of Proto-Indo-European became isolated from each other through the Indo-European migrations ,
936-459: A variety of applications including high-temperature electrochemistry and as an ecologically benign solvent or catalyst in chemical reactions involving organic compounds. In Earth's mantle, it acts as a solvent during mineral formation, dissolution and deposition. The normal form of ice on the surface of Earth is ice I h , a phase that forms crystals with hexagonal symmetry . Another with cubic crystalline symmetry , ice I c , can occur in
1008-410: A water molecule, the hydrogen atoms form a 104.5° angle with the oxygen atom. The hydrogen atoms are close to two corners of a tetrahedron centered on the oxygen. At the other two corners are lone pairs of valence electrons that do not participate in the bonding. In a perfect tetrahedron, the atoms would form a 109.5° angle, but the repulsion between the lone pairs is greater than the repulsion between
1080-435: Is 917 kg/m (57.25 lb/cu ft), an expansion of 9%. This expansion can exert enormous pressure, bursting pipes and cracking rocks. In a lake or ocean, water at 4 °C (39 °F) sinks to the bottom, and ice forms on the surface, floating on the liquid water. This ice insulates the water below, preventing it from freezing solid. Without this protection, most aquatic organisms residing in lakes would perish during
1152-422: Is a consistent correspondence of the initial consonants ( p and f ) that emerges far too frequently to be coincidental, one can infer that these languages stem from a common parent language . Detailed analysis suggests a system of sound laws to describe the phonetic and phonological changes from the hypothetical ancestral words to the modern ones. These laws have become so detailed and reliable as to support
1224-567: Is believed to have had an elaborate system of morphology that included inflectional suffixes (analogous to English child, child's, children, children's ) as well as ablaut (vowel alterations, as preserved in English sing, sang, sung, song ) and accent . PIE nominals and pronouns had a complex system of declension , and verbs similarly had a complex system of conjugation . The PIE phonology , particles , numerals , and copula are also well-reconstructed. Asterisks are used by linguists as
1296-483: Is important in many geological processes. Groundwater is present in most rocks , and the pressure of this groundwater affects patterns of faulting . Water in the mantle is responsible for the melt that produces volcanoes at subduction zones . On the surface of the Earth, water is important in both chemical and physical weathering processes. Water, and to a lesser but still significant extent, ice, are also responsible for
1368-464: Is it a noble gas (and therefore is not removed from the atmosphere through chemical reactions with other elements), but comparisons between the abundances of its nine stable isotopes in the modern atmosphere reveal that the Earth lost at least one ocean of water early in its history, between the Hadean and Archean eons. Any water on Earth during the latter part of its accretion would have been disrupted by
1440-477: Is merely semantic. Proto-Indo-European language Caucasus East Asia Eastern Europe Northern Europe Pontic Steppe Northern/Eastern Steppe Europe South Asia Steppe Europe Caucasus India Indo-Aryans Iranians East Asia Europe East Asia Europe Indo-Aryan Iranian Indo-Aryan Iranian Others European Proto-Indo-European ( PIE )
1512-419: Is poor at dissolving nonpolar substances. This allows it to be the " solvent of life": indeed, water as found in nature almost always includes various dissolved substances, and special steps are required to obtain chemically pure water . Water is the only common substance to exist as a solid , liquid, and gas in normal terrestrial conditions. Along with oxidane , water is one of the two official names for
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#17328448756991584-424: Is the reconstructed common ancestor of the Indo-European language family . No direct record of Proto-Indo-European exists; its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. Far more work has gone into reconstructing PIE than any other proto-language , and it is the best understood of all proto-languages of its age. The majority of linguistic work during
1656-458: Is the study of the movement, distribution, and quality of water throughout the Earth. The study of the distribution of water is hydrography . The study of the distribution and movement of groundwater is hydrogeology , of glaciers is glaciology , of inland waters is limnology and distribution of oceans is oceanography . Ecological processes with hydrology are in the focus of ecohydrology . The collective mass of water found on, under, and over
1728-677: The Earth's crust , although the compositions of the deep mantle remain active areas of investigation. All allotropes (structurally different pure forms of an element) and some simple carbon compounds are often considered inorganic. Examples include the allotropes of carbon ( graphite , diamond , buckminsterfullerene , graphene , etc.), carbon monoxide CO , carbon dioxide CO 2 , carbides , and salts of inorganic anions such as carbonates , cyanides , cyanates , thiocyanates , isothiocyanates , etc. Many of these are normal parts of mostly organic systems, including organisms ; describing
1800-549: The Indian subcontinent became aware of similarities between Indo-Iranian languages and European languages, and as early as 1653, Marcus Zuerius van Boxhorn had published a proposal for a proto-language ("Scythian") for the following language families: Germanic , Romance , Greek , Baltic , Slavic , Celtic , and Iranian . In a memoir sent to the Académie des Inscriptions et Belles-Lettres in 1767, Gaston-Laurent Coeurdoux ,
1872-477: The Moon-forming impact (~4.5 billion years ago), which likely vaporized much of Earth's crust and upper mantle and created a rock-vapor atmosphere around the young planet. The rock vapor would have condensed within two thousand years, leaving behind hot volatiles which probably resulted in a majority carbon dioxide atmosphere with hydrogen and water vapor . Afterward, liquid water oceans may have existed despite
1944-576: The Neogrammarian hypothesis : the Indo-European sound laws apply without exception. William Jones , an Anglo-Welsh philologist and puisne judge in Bengal , caused an academic sensation when in 1786 he postulated the common ancestry of Sanskrit , Greek , Latin , Gothic , the Celtic languages , and Old Persian , but he was not the first to state such a hypothesis. In the 16th century, European visitors to
2016-428: The elements hydrogen and oxygen by passing an electric current through it—a process called electrolysis . The decomposition requires more energy input than the heat released by the inverse process (285.8 kJ/ mol , or 15.9 MJ/kg). Liquid water can be assumed to be incompressible for most purposes: its compressibility ranges from 4.4 to 5.1 × 10 Pa in ordinary conditions. Even in oceans at 4 km depth, where
2088-526: The molar volumes of the liquid and solid phases, and L f {\displaystyle L_{\text{f}}} is the molar latent heat of melting. In most substances, the volume increases when melting occurs, so the melting temperature increases with pressure. However, because ice is less dense than water, the melting temperature decreases. In glaciers, pressure melting can occur under sufficiently thick volumes of ice, resulting in subglacial lakes . The Clausius-Clapeyron relation also applies to
2160-400: The water cycle consisting of the following transfer processes: Inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds — that is, a compound that is not an organic compound . The study of inorganic compounds is a subfield of chemistry known as inorganic chemistry . Inorganic compounds comprise most of
2232-447: The water cycle of evaporation , transpiration ( evapotranspiration ), condensation , precipitation, and runoff , usually reaching the sea. Water plays an important role in the world economy . Approximately 70% of the fresh water used by humans goes to agriculture . Fishing in salt and fresh water bodies has been, and continues to be, a major source of food for many parts of the world, providing 6.5% of global protein. Much of
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2304-471: The 19th century was devoted to the reconstruction of PIE and its daughter languages , and many of the modern techniques of linguistic reconstruction (such as the comparative method ) were developed as a result. PIE is hypothesized to have been spoken as a single language from approximately 4500 BCE to 2500 BCE during the Late Neolithic to Early Bronze Age , though estimates vary by more than
2376-443: The Earth was younger and less massive , water would have been lost to space more easily. Lighter elements like hydrogen and helium are expected to leak from the atmosphere continually, but isotopic ratios of heavier noble gases in the modern atmosphere suggest that even the heavier elements in the early atmosphere were subject to significant losses. In particular, xenon is useful for calculations of water loss over time. Not only
2448-475: The Indo-European root, with Greek ύδωρ ( ýdor ; from Ancient Greek ὕδωρ ( hýdōr ), whence English ' hydro- ' ), Russian вода́ ( vodá ), Irish uisce , and Albanian ujë . One factor in estimating when water appeared on Earth is that water is continually being lost to space. H 2 O molecules in the atmosphere are broken up by photolysis , and the resulting free hydrogen atoms can sometimes escape Earth's gravitational pull. When
2520-558: The North Adriatic region are sometimes classified as Italic. Albanian and Greek are the only surviving Indo-European descendants of a Paleo-Balkan language area, named for their occurrence in or in the vicinity of the Balkan peninsula . Most of the other languages of this area—including Illyrian , Thracian , and Dacian —do not appear to be members of any other subfamilies of PIE, but are so poorly attested that proper classification of them
2592-622: The Pontic–Caspian steppe and into eastern Europe. Other theories include the Anatolian hypothesis , which posits that PIE spread out from Anatolia with agriculture beginning c. 7500–6000 BCE, the Armenian hypothesis , the Paleolithic continuity paradigm , and the indigenous Aryans theory. The last two of these theories are not regarded as credible within academia. Out of all the theories for
2664-517: The Proto-Indo-European and Proto-Kartvelian languages due to early language contact , as well as some morphological similarities—notably the Indo-European ablaut , which is remarkably similar to the root ablaut system reconstructible for Proto-Kartvelian. The Lusitanian language was a marginally attested language spoken in areas near the border between present-day Portugal and Spain . The Venetic and Liburnian languages known from
2736-431: The boiling point of water is 100 °C (212 °F). As atmospheric pressure decreases with altitude, the boiling point decreases by 1 °C every 274 meters. High-altitude cooking takes longer than sea-level cooking. For example, at 1,524 metres (5,000 ft), cooking time must be increased by a fourth to achieve the desired result. Conversely, a pressure cooker can be used to decrease cooking times by raising
2808-590: The boiling point, but with the liquid/gas transition the vapor phase has a much lower density than the liquid phase, so the boiling point increases with pressure. Water can remain in a liquid state at high temperatures in the deep ocean or underground. For example, temperatures exceed 205 °C (401 °F) in Old Faithful , a geyser in Yellowstone National Park . In hydrothermal vents , the temperature can exceed 400 °C (752 °F). At sea level ,
2880-400: The boiling temperature. In a vacuum, water will boil at room temperature. On a pressure/temperature phase diagram (see figure), there are curves separating solid from vapor, vapor from liquid, and liquid from solid. These meet at a single point called the triple point , where all three phases can coexist. The triple point is at a temperature of 273.16 K (0.01 °C; 32.02 °F) and
2952-777: The chemical compound H 2 O ; it is also the liquid phase of H 2 O . The other two common states of matter of water are the solid phase, ice , and the gaseous phase, water vapor or steam . The addition or removal of heat can cause phase transitions : freezing (water to ice), melting (ice to water), vaporization (water to vapor), condensation (vapor to water), sublimation (ice to vapor) and deposition (vapor to ice). Water differs from most liquids in that it becomes less dense as it freezes. In 1 atm pressure, it reaches its maximum density of 999.972 kg/m (62.4262 lb/cu ft) at 3.98 °C (39.16 °F), or almost 1,000 kg/m (62.43 lb/cu ft) at almost 4 °C (39 °F). The density of ice
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3024-588: The common origin of Sanskrit, Persian, Greek, Latin, and German. In 1833, he began publishing the Comparative Grammar of Sanskrit, Zend , Greek, Latin, Lithuanian, Old Slavic, Gothic, and German . In 1822, Jacob Grimm formulated what became known as Grimm's law as a general rule in his Deutsche Grammatik . Grimm showed correlations between the Germanic and other Indo-European languages and demonstrated that sound change systematically transforms all words of
3096-577: The effects of hypothetical sounds which no longer exist in all languages documented prior to the excavation of cuneiform tablets in Anatolian. This theory was first proposed by Ferdinand de Saussure in 1879 on the basis of internal reconstruction only, and progressively won general acceptance after Jerzy Kuryłowicz 's discovery of consonantal reflexes of these reconstructed sounds in Hittite. Julius Pokorny 's Indogermanisches etymologisches Wörterbuch ('Indo-European Etymological Dictionary', 1959) gave
3168-485: The force of gravity . This property is relied upon by all vascular plants , such as trees. Water is a weak solution of hydronium hydroxide—there is an equilibrium 2H 2 O ⇌ H 3 O + OH , in combination with solvation of the resulting hydronium and hydroxide ions. Pure water has a low electrical conductivity , which increases with the dissolution of a small amount of ionic material such as common salt . Liquid water can be split into
3240-476: The form of snow . The gaseous state of water is steam or water vapor . Water covers about 71% of the Earth's surface, with seas and oceans making up most of the water volume (about 96.5%). Small portions of water occur as groundwater (1.7%), in the glaciers and the ice caps of Antarctica and Greenland (1.7%), and in the air as vapor , clouds (consisting of ice and liquid water suspended in air), and precipitation (0.001%). Water moves continually through
3312-418: The hydrogen atoms. The O–H bond length is about 0.096 nm. Other substances have a tetrahedral molecular structure, for example methane ( CH 4 ) and hydrogen sulfide ( H 2 S ). However, oxygen is more electronegative than most other elements, so the oxygen atom has a negative partial charge while the hydrogen atoms are partially positively charged. Along with the bent structure, this gives
3384-476: The light source is sunlight reflected from the pool's white tiles. In nature, the color may also be modified from blue to green due to the presence of suspended solids or algae. In industry, near-infrared spectroscopy is used with aqueous solutions as the greater intensity of the lower overtones of water means that glass cuvettes with short path-length may be employed. To observe the fundamental stretching absorption spectrum of water or of an aqueous solution in
3456-427: The liquid and vapor phases form a continuous phase called a supercritical fluid . It can be gradually compressed or expanded between gas-like and liquid-like densities; its properties (which are quite different from those of ambient water) are sensitive to density. For example, for suitable pressures and temperatures it can mix freely with nonpolar compounds , including most organic compounds . This makes it useful in
3528-413: The liquid is known as boiling ). Sublimation and deposition also occur on surfaces. For example, frost is deposited on cold surfaces while snowflakes form by deposition on an aerosol particle or ice nucleus. In the process of freeze-drying , a food is frozen and then stored at low pressure so the ice on its surface sublimates. The melting and boiling points depend on pressure. A good approximation for
3600-750: The liquid or solid state can form up to four hydrogen bonds with neighboring molecules. Hydrogen bonds are about ten times as strong as the Van der Waals force that attracts molecules to each other in most liquids. This is the reason why the melting and boiling points of water are much higher than those of other analogous compounds like hydrogen sulfide. They also explain its exceptionally high specific heat capacity (about 4.2 J /(g·K)), heat of fusion (about 333 J/g), heat of vaporization ( 2257 J/g ), and thermal conductivity (between 0.561 and 0.679 W/(m·K)). These properties make water more effective at moderating Earth's climate , by storing heat and transporting it between
3672-1069: The long-distance trade of commodities (such as oil, natural gas, and manufactured products) is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating in industry and homes. Water is an excellent solvent for a wide variety of substances, both mineral and organic; as such, it is widely used in industrial processes and in cooking and washing. Water, ice, and snow are also central to many sports and other forms of entertainment, such as swimming , pleasure boating, boat racing , surfing , sport fishing , diving , ice skating , snowboarding , and skiing . The word water comes from Old English wæter , from Proto-Germanic * watar (source also of Old Saxon watar , Old Frisian wetir , Dutch water , Old High German wazzar , German Wasser , vatn , Gothic 𐍅𐌰𐍄𐍉 ( wato )), from Proto-Indo-European * wod-or , suffixed form of root * wed- ( ' water ' ; ' wet ' ). Also cognate , through
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#17328448756993744-654: The main Indo-European language families, comprising the languages descended from Proto-Indo-European. Slavic: Russian , Ukrainian , Belarusian , Polish , Czech , Slovak , Sorbian , Serbo-Croatian , Bulgarian , Slovenian , Macedonian , Kashubian , Rusyn Iranic: Persian , Pashto , Balochi , Kurdish , Zaza , Ossetian , Luri , Talyshi , Tati , Gilaki , Mazandarani , Semnani , Yaghnobi ; Nuristani Commonly proposed subgroups of Indo-European languages include Italo-Celtic , Graeco-Aryan , Graeco-Armenian , Graeco-Phrygian , Daco-Thracian , and Thraco-Illyrian . There are numerous lexical similarities between
3816-545: The molecule an electrical dipole moment and it is classified as a polar molecule . Water is a good polar solvent , dissolving many salts and hydrophilic organic molecules such as sugars and simple alcohols such as ethanol . Water also dissolves many gases, such as oxygen and carbon dioxide —the latter giving the fizz of carbonated beverages, sparkling wines and beers. In addition, many substances in living organisms, such as proteins , DNA and polysaccharides , are dissolved in water. The interactions between water and
3888-524: The most popular. It proposes that the original speakers of PIE were the Yamnaya culture associated with the kurgans (burial mounds) on the Pontic–Caspian steppe north of the Black Sea. According to the theory, they were nomadic pastoralists who domesticated the horse , which allowed them to migrate across Europe and Asia in wagons and chariots. By the early 3rd millennium BCE, they had expanded throughout
3960-416: The oceans and the atmosphere. The hydrogen bonds of water are around 23 kJ/mol (compared to a covalent O-H bond at 492 kJ/mol). Of this, it is estimated that 90% is attributable to electrostatics, while the remaining 10% is partially covalent. These bonds are the cause of water's high surface tension and capillary forces. The capillary action refers to the tendency of water to move up a narrow tube against
4032-482: The oceans may have always been on the Earth since the beginning of the planet's formation . Water ( H 2 O ) is a polar inorganic compound . At room temperature it is a tasteless and odorless liquid , nearly colorless with a hint of blue . The simplest hydrogen chalcogenide , it is by far the most studied chemical compound and is sometimes described as the "universal solvent" for its ability to dissolve more substances than any other liquid, though it
4104-486: The oxygen atom at an angle of 104.45°. In liquid form, H 2 O is also called "water" at standard temperature and pressure . 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
4176-435: The parts of the oceans below 1,000 metres (3,300 ft) of depth. The refractive index of liquid water (1.333 at 20 °C (68 °F)) is much higher than that of air (1.0), similar to those of alkanes and ethanol , but lower than those of glycerol (1.473), benzene (1.501), carbon disulfide (1.627), and common types of glass (1.4 to 1.6). The refraction index of ice (1.31) is lower than that of liquid water. In
4248-448: The presence of water in their mouths, and frogs are known to be able to smell it. However, water from ordinary sources (including mineral water ) usually has many dissolved substances that may give it varying tastes and odors. Humans and other animals have developed senses that enable them to evaluate the potability of water in order to avoid water that is too salty or putrid . Pure water is visibly blue due to absorption of light in
4320-435: The pressure is 400 atm, water suffers only a 1.8% decrease in volume. The viscosity of water is about 10 Pa· s or 0.01 poise at 20 °C (68 °F), and the speed of sound in liquid water ranges between 1,400 and 1,540 metres per second (4,600 and 5,100 ft/s) depending on temperature. Sound travels long distances in water with little attenuation , especially at low frequencies (roughly 0.03 dB /km for 1 k Hz ),
4392-426: The proto-Indo-European language. By the early 1900s, Indo-Europeanists had developed well-defined descriptions of PIE which scholars still accept today. Later, the discovery of the Anatolian and Tocharian languages added to the corpus of descendant languages. A subtle new principle won wide acceptance: the laryngeal theory , which explained irregularities in the reconstruction of Proto-Indo-European phonology as
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#17328448756994464-587: The rate of change of the melting temperature with pressure is given by the Clausius–Clapeyron relation : d T d P = T ( v L − v S ) L f {\displaystyle {\frac {dT}{dP}}={\frac {T\left(v_{\text{L}}-v_{\text{S}}\right)}{L_{\text{f}}}}} where v L {\displaystyle v_{\text{L}}} and v S {\displaystyle v_{\text{S}}} are
4536-569: The region around 3,500 cm (2.85 μm) a path length of about 25 μm is needed. Also, the cuvette must be both transparent around 3500 cm and insoluble in water; calcium fluoride is one material that is in common use for the cuvette windows with aqueous solutions. The Raman-active fundamental vibrations may be observed with, for example, a 1 cm sample cell. Aquatic plants , algae , and other photosynthetic organisms can live in water up to hundreds of meters deep, because sunlight can reach them. Practically no sunlight reaches
4608-459: The region c. 600–800 nm. The color can be easily observed in a glass of tap-water placed against a pure white background, in daylight. The principal absorption bands responsible for the color are overtones of the O–H stretching vibrations . The apparent intensity of the color increases with the depth of the water column, following Beer's law . This also applies, for example, with a swimming pool when
4680-428: The regional dialects of Proto-Indo-European spoken by the various groups diverged, as each dialect underwent shifts in pronunciation (the Indo-European sound laws ), morphology, and vocabulary. Over many centuries, these dialects transformed into the known ancient Indo-European languages. From there, further linguistic divergence led to the evolution of their current descendants, the modern Indo-European languages. PIE
4752-708: The set of correspondences in his prize essay Undersøgelse om det gamle Nordiske eller Islandske Sprogs Oprindelse ('Investigation of the Origin of the Old Norse or Icelandic Language'), where he argued that Old Norse was related to the Germanic languages, and had even suggested a relation to the Baltic, Slavic, Greek, Latin and Romance languages. In 1816, Franz Bopp published On the System of Conjugation in Sanskrit , in which he investigated
4824-413: The subunits of these biomacromolecules shape protein folding , DNA base pairing , and other phenomena crucial to life ( hydrophobic effect ). Many organic substances (such as fats and oils and alkanes ) are hydrophobic , that is, insoluble in water. Many inorganic substances are insoluble too, including most metal oxides , sulfides , and silicates . Because of its polarity, a molecule of water in
4896-487: The surface of a planet is called the hydrosphere . Earth's approximate water volume (the total water supply of the world) is 1.386 billion cubic kilometres (333 million cubic miles). Liquid water is found in bodies of water , such as an ocean, sea, lake, river, stream, canal , pond, or puddle . The majority of water on Earth is seawater . Water is also present in the atmosphere in solid, liquid, and vapor states. It also exists as groundwater in aquifers . Water
4968-533: The surface temperature of 230 °C (446 °F) due to the increased atmospheric pressure of the CO 2 atmosphere. As the cooling continued, most CO 2 was removed from the atmosphere by subduction and dissolution in ocean water, but levels oscillated wildly as new surface and mantle cycles appeared. Geological evidence also helps constrain the time frame for liquid water existing on Earth. A sample of pillow basalt (a type of rock formed during an underwater eruption)
5040-456: The upper atmosphere. As the pressure increases, ice forms other crystal structures . As of 2024, twenty have been experimentally confirmed and several more are predicted theoretically. The eighteenth form of ice, ice XVIII , a face-centred-cubic, superionic ice phase, was discovered when a droplet of water was subject to a shock wave that raised the water's pressure to millions of atmospheres and its temperature to thousands of degrees, resulting in
5112-438: The winter. Water is a diamagnetic material. Though interaction is weak, with superconducting magnets it can attain a notable interaction. At a pressure of one atmosphere (atm), ice melts or water freezes (solidifies) at 0 °C (32 °F) and water boils or vapor condenses at 100 °C (212 °F). However, even below the boiling point, water can change to vapor at its surface by evaporation (vaporization throughout
5184-780: Was recovered from the Isua Greenstone Belt and provides evidence that water existed on Earth 3.8 billion years ago. In the Nuvvuagittuq Greenstone Belt , Quebec, Canada, rocks dated at 3.8 billion years old by one study and 4.28 billion years old by another show evidence of the presence of water at these ages. If oceans existed earlier than this, any geological evidence has yet to be discovered (which may be because such potential evidence has been destroyed by geological processes like crustal recycling ). More recently, in August 2020, researchers reported that sufficient water to fill
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