Fr.: fréquence de Brunt-Väisälä
The frequency at which an air parcel will oscillate when subjected to an infinitesimal perturbation in a stably stratified atmosphere. For a medium with a continuous density gradient, it is expressed by the formula: N2 = -(g/ρ)∂ρ/∂z , where g is the → gravitational acceleration, ρ is density, and z geometric height. The stability condition is N > 0. It is also sometimes referred to as the buoyancy frequency. The higher the value of N the more stable the flow.
Named aster David Brunt (1886-1965), British meteorologist (1927, Q.J.R.Met.Soc. 53, 30) and Vilho Väisälä (1889-1969), Finnish meteorologist (1925, Soc. Sci. Fenn. Commental. Phys. Math. 2 (19), 19); → frequency.
General:A small body of gas within a liquid; a thin film of
liquid inflated with air or gas.
Bubble, from M.E. bobel, perhaps from M.Du. bobbel.
Tangol "bubble," from Âštiyâni dialect, maybe
from tan "body" + gol "flower," literally
"that which has a delicate body (like a flower)." This etymology
is derived from the observation that in Pers. bubble is often likened
to a flower:
qonce-ye âb, kupale-ye âb, quze-ye âb
[Dehxodâ] "water blossom, water flower, water bud."
otâqak-e tangol, ~ hobâb
Fr.: chambre à bulles
A tank filled with a transparent liquid that is on the brink of boiling. When a charged particle passes through the liquid, the energy deposited initiates boiling along the path, leaving a trail of tiny bubbles. The bubble chamber is no longer in wide use for particle experiments.
miq-e tangol, ~ hobâb
Fr.: Nébuleuse bulle
Fr.: bug, bogue
A defect or imperfection, as in a mechanical device, computer program, or plan (Dictionary.com).
From bugge "beetle," apparently alteration of M.E. budde, O.E. -budda "beetle."
Bug, from Kurd. Kurmanji bihuk "bug, insect."
Fr.: nébuleuse de l'insecte
The double-lobed → planetary nebula NGC 6302, which lies in → Scorpius at a distance of about 4000 → light-years. The central very hot star seems to have violently ejected material in two distinct directions.
Šâparak "night butterfly, bat," from šab "night" + parak "flying," from paridan "to fly."
Fr.: bulbe, bourrelet
1) A rounded projection, bend, or protruding part; protuberance; hump (Dictionary.com).
Bulge, from O.Fr. bouge "leather bag," from L. bulga "leather bag," of Gaulish origin.
Kuži "convexity," from kuž, → convex.
1) A small, metal object that is fired from a gun.
From M.Fr. boulette "cannonball, small ball," diminutive of boule "a ball," from L. bulla "round thing, bubble, knob," cognate with bowl and boil.
Golulé "bullet," variants gullé, goruk, gulu, gudé, guy "ball, sphere;" cf. Skt. guda- "ball, mouthful, lump, tumour;" Pali gula- "ball;" Gk. gloutos "rump;" L. glomus "ball," globus "globe;" Ger. Kugel, E. clot; PIE *gel- "to make into a ball."
Fr.: amas de la Balle, ~ du Boulet
A → cluster of galaxies at a → redshift of z = 0.296 undergoing a violent → merger process nearly in the → plane of the sky. Also known as 1E 0657-558. The head-on collision between the main cluster and a subcluster ramming with an apparent speed of about 4700 km s-1 occurred about 150 x 106 years ago. The two clusters are currently moving away from each other while the space between them is filled with a very hot gas (first observed in X-rays by → Chandra) resulting from the overheating due to the collision. The Bullet cluster has the highest X-ray luminosity and temperature of all known clusters. The X-ray gas of the bullet (amounting to 2 x 1013 solar masses) collides with the X-ray gas of the main cluster (1014 solar masses) and forms a well defined → supersonic (Mach 3) → bow shock. A significant offset between the distribution of X-ray emission and the mass distribution has been observed, and diversely interpreted.
The name Bullet refers to the smaller subcluster, that has created the bow shock; → cluster.
Kefeusi-ye quzâr, ~ zokdâr
Fr.: céphéide à bosse
Bump "a relatively abrupt convexity or bulge on a surface," probably imitative of the sound of a blow; → Cepheid.
Quzdâr, from quz "hump," variant of kuž→ convex + -dâr "possessing," from dâštan "to have, possess." Zokdâr, from Lori zok "a raised spot, a bulge," cf. Northern Fârs Âbâdé dialect lok " swellimg, knob;" Kefeusi, → Cepheid.
The upward force that a → fluid exerts on an immersed body which is less dense than the fluid. It is equal to the → weight of the fluid displaced. Thus a body weighs less when weighed in water, the apparent loss in weight being equal to the weight of the water displaced. Buoyancy allows a boat to float on water and provides lift for balloons. See also → buoyant force; → Archimedes' principle.
From buoy, → buoyant + -ancy a suffix used to form nouns denoting state or quality, from L. -antia, from -ant + -ia.
Bâlârâni literally "pushing up," from bâlâ "up, above, high, elevated, height" (variants boland "high, tall, elevated, sublime," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Laki dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. and E. force); O.E. burg, burh "castle, fortified place," from P.Gmc. *burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city," E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg; PIE base *bhergh- "high") + râni verbal noun of rândan "to push, drive, cause to go," causative of raftan "to go, walk, proceed" (present tense stem row-, Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack").
Fr.: fréquence de flottabilité
Same as the → Brunt-Vaisala frequency.
Fr.: poussée d'Archimède
From buoy (current meaning) "a float moored in water to mark a location," from M.E. boye, from O.Fr. buie or M.Du. boeye, from L. boia "fetter, chain" + suffix -ant; → force.
1) suxtan; 2) suzândan
1) (v.intr.) To undergo combustion (fast or slow).
Burn, from M.E. bernen, brennen, combination of O.E. beornan (intr.) and bærnan (tr.), both from P.Gmc. *brenwanan; cf. Goth. brannjan, O.H.G. brennen.
Suxtan, suzândan, from Mid.Pers. sôxtan, sôzidan "to burn;" Av. base saoc- "to burn, inflame" sūcā "brilliance," upa.suxta- "inflamed;" cf. Skt. śoc- "to light, glow, burn," śocati "burns," (caus.) socayati, śuc- "flame, glow," śoka- "light, flame;" PIE base *(s)keuk- "to shine."
Verbal noun of → burn.
Fr.: sphère ardente
A piece of glass of roundish shape, possibly made of rock crystals or a globular container filled with water, whose use is attested in ancient civilizations. In his comedy The Clouds, the Greek playwright Aristophanes (448-380 BC) mentions globules of glass that were known as burning spheres. Several Roman writers (Pliny, Seneca, Plutarch) speak of burning glasses. In particular, Seneca specifies that small and indistinct written characters appear larger and clearer when viewed through a globular glass filled with water. See also → magnifying glass.
1) belk; 2) belkidan
Fr.: 1) sursaut, flambée, impulsion; 2) éclater
1a) General: An abrupt, intense increase. A period of intense
activity. A sudden outbreak or outburst. An explosion.
M.E. bersten, from O.E. berstan, akin to O.H.G. berstan "to burst;" from PIE *bhres- "to burst, break, crack."
1) Belk, Mod.Pers. "a blaze, a flame." The term has several
variants, including in dialects: balk [Mo'in],
pâlk (Tokharian AB),
bal (Gilaki, Semnâni, Sorxeyi, Sangesari, Lahijâni),
val (Gilaki), bilese (Kordi), beleyz (Lori),
warq, barx [Mo'in], and the Pers. widespread term gorr
"burst of fire."
Belk derives probably from Mid.Pers. brâh, Av. braz-
"to shine, gleam, flash, radiate,"
cf. Skt. bhâ- "to shine," bhrajate "shines, glitters,"
O.H.G. beraht "bright,"
O.E. beorht "bright;" PIE *bhereg- "to shine."
The Mod.Pers. barq "glitter; → electricity" probably
belongs to this family. Therefore, the Hebrew barak and Ar. barq
may be loanwords from Old or Mid.Pers.
burst of star formation
belk-e diseš-e setâregân
Fr.: flambée de formation d'étoiles
An intense → star formation activity in a region of → interstellar medium or, more globally, in a → galaxy. It is characterized by a → star formation rate which is much higher than the corresponding average. Same as → starburst.
Fr.: source à sursaut
From → burst + -er a noun-forming suffix.
Belkvar, from belk, → burst, + agent noun suffix -var.
Fr.: diagramme en papillon
A graph on which the latitudes of → sunspots are plotted against time. It shows how sunspots migrate from high latitudes (30°- 40° north or south) to the solar equator (latitude of about 5°) during each → solar cycle, according to → Sporer's law. The shape of these distributions, when represented for both hemispheres, resembles the wings of a butterfly. The diagram was first created by Edward W. Maunder in 1904 to illustrate the solar cycle (M.S.: SDE).
Butterfly, from M.E. butterflye, from O.E. butorfleoge, from butor, butere "butter" floge "fly," but the etymology is not clear; → diagram.
Nemudâr, → diagram; parvânevâr "resembling a butterfly," from parvâné "butterfly" + -vâr similarity suffix.