Fr.: albedo géométrique
A measure of the → reflectivity of a surface, especially of the solar system bodies (planets, satellites or asteroids). It is the ratio of a body's brightness at zero → phase angle to the brightness of a perfectly diffusing disk with the same position and apparent size as the body. Geometric albedo depends on the radiation wavelength. The bolometric geometric albedo refers to reflectivity in all wavelengths. Compare with the → Bond albedo.
Fr.: retard géométrique
One of the two factors contributing to → gravitational lensing time delay that arises from the fact that the bent trajectory is longer than the straight one. The other factor is due to the → Shapiro time delay.
Fr.: horizon géométrique
miyângin-e hendesi (#)
Fr.: moyenne géométrique
The middle term in a → geometric progression. Of two terms, the geometric mean is the square root of their product. For example, the geometric mean of 4 and 9 is ± 6. For a series of n terms, it is expressed as: (a1.a2. ... .an)1/n.
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."