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Baro- combining form of Gk. baros "weight;" cognate with Pers. bâr "weight," gerân "heavy;" cf. Skt. guru, L. gravis; PIE *gwere- "heavy;" L. brutus "heavy, dull, stupid, brutish;" Skt. bhara- "burden, load," bharati "he carries;" PIE *bher- "carry, give birth."
Fešâr-, → pressure.
Fr.: instabilité barocline
1) A type of instability occurring within a rapidly → rotating star
where non-axisymmetric motions can separate surfaces of constant pressure from
→ equipotential surfaces.
The state of stratification in a fluid in which surfaces of constant pressure do not coincide with those of constant density, but intersect. Where baroclinicity is zero, the fluid is → barotropic. Same as baroclinity.
Instrument for measuring the atmospheric pressure. It is used in determining height above sea level and predicting changes in weather.
qânun-e fešârsanji, ~ fešârsanjik
Fr.: loi barométrique
The atmospheric pressure decreases exponentially from any reference surface as the altitude increases.
In a fluid, conditions where surfaces of constant pressure are parallel to surfaces of constant temperature. This state is equivalent to zero → baroclinicity.
Fr.: gaz barotrope
A gas whose density is a function solely of pressure.
Fr.: instabilité barotrope
A hydrodynamical instability that arises when the horizontal → shear gradient becomes very large. Barotropic instabilities grow by extracting kinetic energy from the mean flow field.
A state of a fluid in which the surfaces of constant density coincide with surfaces of constant pressure (isobaric).
Having a bar like structure.
barred Magellanic spiral
mârpic-e mile-dâr-e Mâželâni
Fr.: spirtale barée magellanique
A transitional class of object between the classic spiral galaxies and true irregular systems. The → Large Magellanic Cloud, the nearest and best studied example of the class, is, contrary to popular opinion, not an irregular galaxy. The LMC and other members of the SBm class have definite structural signatures. They are generally dominated by a pronounced asymmetric bar -- one that is offset from the optical center of the galaxy -- with a nascent spiral arm emanating from one end. As is the case with irregular galaxies, the optical centers of SBm type systems are not particularly special places. Disk systems later than Sc characteristically lack a central stellar concentration in addition to having weak spiral structure; this is true of SBm-type galaxies. SBm galaxies are typically very active in their star formation activity, often containing a large star-forming complex situated at one end of the bar. Beyond these general trends there is a tremendous amount of dispersion in physical properties within the SBm class, particularly in the strength of the spiral structure. At one extreme are the "one-armed" spirals such as NGC 3664 and NGC 4027 which are dominated by single, looping spiral arm. On the other hand NGC 4861 shows little evidence of spiral structure and it is dominated by a large star-forming complex at one end of its bar. The class smoothly leads to the Barred Magellanic irregulars (IBm) which show no indication of spiral structure (Wilcots et al. 1996, AJ 111, 1575).
barred spiral galaxy
kahkašân-e mârpic-e miledâr
Fr.: galaxie spirale barrée
cowlegi-ye celiki (#)
Fr.: distortion en barillet
A defect in an optical system in which magnification decreases with distance from the optical axis, whereby the image of a square appears barrel-shaped. Opposite of → pincushion distortion.
Barrel, M.E. barel, from O.Fr. baril; → distortion.
Cowlegi, → distortion; celiki, relating to celik "barrel".
General: Anything that prevents passage or blocks.
O.F. barrière "obstacle," from V.L. *barraria, from *barra "bar, barrier."
Varqé, from varq "a mound, a dam" + -é nuance suffix. Varq is probably related to Av. vâra- "barrage," vara- "enclosure," var- "castle," Mid.Pers. var "enclosure," from Av. root var- "to cover, to conceal;" variants: barq (Torbat Heydariyei), valgâ (Âštiyâni), var (Qomi); cf. Skt. vatra- "a dike, a dam,"varana- "rampart, wall," from vr- "to obstruct, close, cover, hide; to choose."
Fr.: cratère Barringer
Same as → Meteor Crater.
The center of mass of a system of bodies.
Gerânigâh, from gerâni "weight;" cognate with Gk. barus, → bar, + gâh "place."
Barycentric Coordinate Time (TCB)
zamân-e hamârâ-ye gerânigâhi
Fr.: temps-coordonnée barycentrique (TCB)
A → coordinate time having its spatial origin at the solar system barycenter. It is intended to be used as the independent variable of time for all calculations pertaining to orbits of planets, asteroids, comets, and interplanetary spacecraft in the solar system. → Barycentric Dynamical Time (IDB).
Barycentric Dynamical Time (TDB)
zamân-e tavânik-e gerânigâhi
Fr.: temps dynamique barycentrique (TDB)
A time scale previously used in calculations of the orbits of solar system objects (planets, asteroids, comets, and interplanetary spacecrafts). It was based on the Terrestrial Dynamical Time, but took the relativistic effect of time dilation into account to move the origin to the solar system barycenter. It is now superseded by → Barycentric Coordinate Time (TCB).
Barycentric Julian Date (BJD)
gâhdâd-e žulian-e gerânigâhi
Fr.: date julienne barycentrique
The → Julian Date referenced to the → barycenter of the → solar system. The BJD is more precise than the → Heliocentric Julian Day because the Sun is not stationary. It moves due to the → gravitational attraction of Jupiter and the other planets.