An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

Turned into or covered with → ice. See also: → water ice.

Past participle of → freeze.

Water in which the hydrogen is replaced by → deuterium. Deuterium Oxide (D₂O).

→ heavy; → water.

Also known as → high tide.

→ high; → water.

Water in a state that is neither ice nor vapor.

→ liquid; → water.

Also known as → low tide.

→ low; → water.

The density of pure water occurring at 3.98 °C, which is 1.0000 g cm^-3, or 1000 kg m^-3. Water when cooled down contracts normally until the temperature is 3.98 °C, after which it expands. Because the maximum density of water occurs at about 4 °C, water becomes increasingly lighter at 3 °C, 2 °C, 1 °C, and 0 °C (→ freezing point). The density of liquid water at 0 °C is greater than the density of frozen water at the same temperature. Thus water is heavier as a liquid than as a solid, and this is why ice floats on water. When a mass of water cools below 4 °C, the density decreases and allows water to rise to the surface, where freezing occurs. The layer of ice formed on the surface does not sink and it acts as a thermal isolator, thus protecting the biological environment beneath it. This property of water liquid is very unusual; molecules pack more closely than in the crystal structure of ice. The reason is that → hydrogen bonds between liquid water are not stable, they are continuously broken and new bonds are created. In the crystal structure of ice molecules have a fixed pattern creating empty space between molecules.

→ maximum; → density; → water.

The → water molecule in which the → nuclear spin of the constituent → hydrogen atoms are → parallel (→ orthohydrogen). In astrophysics the ratio between ortho- and → para-water is used to determine temperatures in → interstellar medium.

→ ortho-; → water.

The → water molecule in which the → nuclear spins of the constituent → hydrogen atoms are → antiparallel (→ parahydrogen). See also: → ortho-water.

→ para-; → water.

The normal oxide of hydrogen with formula H₂O. Pure water's → melting point is 0°C and its → boiling point 100 °C at sea level. Water has a → maximum density at very nearly 4°C of (by definition) 1.0000 g cm^-3. It then expands as its temperature drops to 0°C, the density being 0.9998 g cm^-3 . On freezing, it expands still further, giving ice a density of 0.9168 g cm^-3 at 0°C, whereas water has a density of 0.9998 g cm^-3 at 4 °C. A → water molecule consists of one → oxygen (O) atom bonded to two → hydrogen (H) atoms. The → specific heat of water, 1 calorie per gram per 1 degree C (cal/g/°C), is higher than most other substances. Therefore, water both absorbs and releases heat more slowly than land. This causes land areas to heat more rapidly and to higher temperatures and also cool more rapidly and to lower temperatures, compared to oceans. The high heat capacity of water also explains why the temperatures of land near a body of water are more moderate. The high heat capacity of water keeps its temperature within a relatively narrow range, causing nearby coastal areas to also have a narrow daily and seasonal temperature range. See also → heavy water, → ortho-water, → para-water.

Water, from O.E. wæter (cognates: Du. water; O.H.G. wazzar; Ger. Wasser; Goth. wato); cf. Gk. hydro-, combining form of hydor "water," cognate with Skt. udá- "water;" Khotanese ūtcā "water;" Hittite uātar; L. unda "wave;" O.C.S., Rus. voda; Lith. vanduo; from PIE base *wed- "water; wet."

Âb "water," variants iv, êw, âp; from Mid.Pers. âb "water;" O.Pers. ap- "water;" Av. ap- "water;" cf. Skt. áp- "water;" Hitt. happa- "water;" PIE āp-, ab- "water, river;" cf. Gk. Apidanos, proper noun, a river in Thessalia; L. amnis "stream, river" (from *abnis); O.Ir. ab "river," O.Prus. ape "stream," Lith. upé "stream;" Latv. upe "brook."

An ancient form of clock, used by several civilizations, consisting of a water container with a small hole from which the water slowly dripped. Time was reckoned by the level of the water remaining in the container.

→ water; → clock

Pang "a copper bason with a small hole in the bottom, for water in which it is placed to flow through, used for measuring time" used in Iran.

Water in the → solid state, produced by freezing → liquid water; frozen water. Ice forms at or below a temperature of 0°C. Ice is less dense than liquid water because it expands during the process of freezing. This is because the molecular arrangement taken by ice leads to an increase in volume and a decrease in density. → maximum density of water

→ water; → ice.

An interstellar → maser phenomenon in which water (H₂O) molecules undergo the processes of → population inversion and → stimulated emission. H₂O masers are detected toward star formation regions and the envelopes of evolved stars. The maser emission comes from regions that are typically quite small, not larger than the solar system. The main emission frequency is 22 GHz, which shows up in strong lines. There are, however, other H₂O maser transitions at 380 GHz and 183 GHz, which are much weaker than the 22 GHz line. The former transitions are sporadically detected since they are strongly absorbed in the Earth's atmosphere, because of its high water vapor content.

→ water; → maser

The chemical combination of one → oxygen (O) atom bonded to two → hydrogen (H) atoms. The bonding between the oxygen atom and each hydrogen atom is known as → covalent bonds. The two hydrogen atoms are bonded to the oxygen atom at a 105° angle. This geometry of the water molecule causes it to have positively and negatively changed ends, known as → polarity. Water is referred to a polar or dipolar molecule. The large nucleus of the oxygen atom attracts the shared electrons causing this side of the water molecule to be negatively charged while the hydrogen side is positively charged. This polarity allows water to bond easily with adjacent water molecules.

→ water; → molecule.

Same as → ocean planet.

→ water; → planet.

1) Water (H₂O) in the gaseous state.
2) Meteo.: Atmospheric water in vapor form; one of the most important components of the → atmosphere.

→ water; → vapor.

A spinning column of rising humid air that occurs over a body of warm water. Waterspouts fall within the class of atmospheric phenomena known as convective vortices that includes → tornadoes, → dust devils, and → hurricanes. They can feature wind speeds over 200 kilometers per hour.

→ water + spout, from M.E. spouten akin to M.Du. spiten "to spout;" O.E. spiwan "to spew."

Tanure-ye daryâyi, from tanuré (kešidan) "turning and raising in the air," probably from tanidan "to turn, spin," → tension; daryâyi, → marine.