Fr.: optique géométrique
A branch of physics that deals with reflection and refraction of rays of light without reference to the wave or physical nature of light.
farâyâsi-e hendesi (#)
Fr.: progression géométrique
A → sequence in which the ratio of a term to its predecessor is the same for all terms. In general, the nth term has the form ar(n-1), where n is a positive integer, and a and r are nonzero constants; r is called the ratio or common ratio. Also called → geometric sequence.
Fr.: diffusion géométrique
A type of scattering in which the wavelength (of the light or the sound) is much smaller than the size of object causing the scattering.
Fr.: suite géométrique
roxgard-e hendesi (#)
Fr.: libration géométrique
A lunar libration motion either in latitude resulting from the inclination of the Moon's orbit with respect to the ecliptic, or in longitude due to the elliptical shape of the Moon's orbit which causes a change in its aspect as seen from the Earth. → libration; → physical libration.
The branch of mathematics that deals with the nature of space and the size, shape, and other properties of figures as well as the transformations that preserve these properties.
Hendesé, Mid.Pers. handâxtan "to measure," Manichean Mid.Pers. hnds- "to measure," Proto-Iranian ham-, → com-, + *das- "to heap, amass;" cf. Ossetic dasun/dast "to heap up;" Arm. loanword dasel "to arrange (a crowd, people)," das "order, arrangement,"
The branch of physics that deals with the Earth and its environment, including meteorology, oceanography, seismology, and geomagnetism.
The study or the application of the influence of political and economic geography on the politics, national power, foreign policy, etc., of a state (Dictionary.com).
Fr.: orbite géostationnaire
A satellite orbit in the plane of the Earth's equator and 35,880 km above it, at which distance the satellite's period of rotation matches the Earth's and the satellite always remains fixed in the same spot over the Earth.
Of or pertaining to the force produced by the rotation of the Earth.
Fr.: équilibre géostrophique
Fr.: écoulement géostrophique
Oceanography: A flow resulting from → geostrophic balance. In geostrophic flow water moves along the lines of constant pressure or → isobars. Geostrophic flow is characterized by small → Rossby and → Ekman numbers.
Fr.: vent géostrophique
Meteo.: A wind which is balanced by the → Coriolis effect and → pressure gradient force. An air parcel initially at rest will move from high pressure to low pressure because of the pressure gradient force. However, the air parcel in its movement is deflected by the Coriolis force, to the right in the northern hemisphere and to the left on the southern hemisphere. As the wind gains speed, the deflection increases until the Coriolis force equals the pressure gradient force. At this point, the wind will be blowing parallel to the → isobars.
Fr.: orbite géosynchrone
A circular orbit around the Earth identical to a geostationary orbit except that the satellite's orbit does not necessarily lie in the Earth's equatorial plane.
Fr.: monture allemande
An equatorial mounting in which the declination axis is at the end of the polar axis, which is on top of a pier to raise the telescope to a convenient height.
German, from L. Germanus, maybe of Gaulish (Celtic) origin, perhaps originally meaning "noisy" (cf. O.Ir. garim "to shout") or "neighbor" (cf. O.Ir. gair "neighbor"); → mounting.
Barnešând, → mounting; Âlmâni "German," from Âlmân, from Fr. Allemand "German," from P.Gmc. *Alamanniz, probably meaning "all-man" and denoting a wide alliance of tribes. Alternatively, perhaps meaning "foreign men," cognate with L. alius "the other."
Fr.: gérondif, substantif verbal
A noun formed from a verb, denoting an action or state. In English, the gerund is the "-ing" form of a verb when it functions grammatically as a noun in a sentence; it is identical in appearance to the present participle.
From L.L. gerundium, from gerundum "to be carried out," gerundive of gerere "to bear, carry."
Fr.: image fantôme
A faint false image caused by reflection that is sometimes seen in an optical system. In spectroscopy, a false image of a spectral line formed by irregularities in the ruling of diffraction gratings.
Ghost, from O.E. gast "soul, spirit, breath," from P.Gmc. *ghoizdoz (cf. M.Du. gheest, Ger. Geist "spirit, ghost"), from PIE base *ghois- "to be excited, frightened;" cf. Av. zaēša- "horrible, frightful," zôiždišta- "the most loathsome;" Mid./Mod.Pers. zešt "ugly, disgusting;" Goth. usgaisjan "to be afraid;" O.E. gæstan "to frighten."
Parhib "ghost," Pers. word of Xorâsâni dialect.
Ghost Head Nebula
miq-e sar-e parhib
Fr.: Nébuleuse de la Tête de Fantôme
A star forming region in the → Large Magellanic Cloud, a satellite of our Galaxy, as pictured by the → Hubble Space Telescope. It spans about 50 light-years and contains several young, → massive stars.
qul, qulpeykar, kalân (#)
From O.Fr. géant, from V.L. *gagantem, from L. gigas "giant," from Gk. gigas (gen. gigantos), huge and savage monsters, children of Gaia and Uranus, who fought the Olympians but were eventually destroyed by the gods, probably from a pre-Gk. language. The Gk. word was used in Septuagint (the Greek translation of the Jewish Scriptures) to refer to men of great size and strength, hence the expanded use in Western languages.
Qul "an imaginary hideous demon, supposed to devour men and animals," Pers. word
probably related to Skt. grábha- "a demon causing diseases, one who seizes,"
grahila- "possessed by a demon," from
grah-, grabh- "to seize, take," graha
"seizing, holding, perceiving," Av./O.Pers. grab- "to take, seize;"
Mid.Pers. griftan; Mod.Pers. gereftan
"to take, seize;" cf. M.L.G. grabben "to grab,"
from P.Gmc. *grab, E. grab "to take or grasp suddenly;"
PIE base *ghrebh- "to seize."