Fr.: polarisation interstellaire
qotbeš-e xatti (#)
Fr.: polarisation linéaire
Of an electromagnetic radiation, a → polarization in which the electric vibrations are confined to one plane along the direction of propagation. Also called → plane polarization. See also → circular polarization.
linearly polarized light
nur-e qotbide-ye xatti
Fr.: lumière polarisée linéairement
Light exhibiting → linear polarization.
Fr.: polarisabilité moléculaire
The ability of a molecular entity to be distorted from its normal shape by an external → electric field. When a molecule is subjected to an electric field there is a small displacement of electrical centers which induces a dipole in the molecule. More specifically, the molecular polarizability α is defined as the ratio of the induced → dipole moment (p) to the local electric field (E) that produces this dipole moment: α = p/E (in cgse units).
Fr.: polarisation négative
A type of polarization in which the direction of polarization becomes reversed.
North Polar Layered Deposits (NPLD)
Lerdhâ-ye Laye-laye-ye Qotb-e Hudar
Fr.: couches de dépôt du pôle nord
A large area of the north polar region of Mars which is covered with alternating layers of water ice and dust. → South Polar Layered Deposits.
North Polar Spur
šaxâk-e kahkešâni-ye hudari
Fr.: éperon galactique nord
One of the largest coherent structures in the radio sky, projecting from the → Galactic plane at → Galactic longitudel ~ 20° and extending to a very high → Galactic latitudeb ~ +80°. It was first identified in low frequency → radio surveys in the 1950s. The spur is also prominent in → soft X-rays. Its origins and nature have long been debated. However, what causes this phenomena is not well understood. It may be due to a combination of → OB associations and → supernova explosions.
plane of polarization
Fr.: plan de polarisation
In a → linearly polarized light, a plane perpendicular to the → plane of vibration and containing the direction of propagation of light. It is also the plane containing the direction of propagation and the magnetic vector (H) of the electromagnetic light wave.
Fr.: polarisation plane
Same as → linear polarization.
plane polarized light
nur-e qotbide-ye hâmoni
Fr.: lumière polarisée plane
1) qotbi; 2) polâr
Fr.: 1) polaire; 2) polar
1) Of or pertaining to the pole of any sphere, a magnet, an electric cell, etc.
Fr.: alignement polaire
The process or the state of making a → telescope's → polar axis → parallel to the → Earth's → rotation axis, that is with the → true North or → South → celestial pole. When this is accomplished, the sky's motion can be cancelled out simply by turning the axis (either by hand or with a motor → drive) at the same rate as the rotation of the Earth, but in the opposite direction.
âse-ye qotbi (#)
Fr.: axe polaire
The axis of an → equatorial mounting that is parallel to the Earth's axis, and consequently points to the celestial pole.
Fr.: lien polaire
A chemical bond where the electrons are shared unequally between atoms. The atom that is more electronegative will pull the electrons closer to itself.
Fr.: calotte polaire
1) Either of the regions around the poles of the Earth that are permanently
covered with ice.
parhun-e qotbi, dâyere-ye ~ (#)
Fr.: cercle polaire
An imaginary parallel circle on the celestial sphere or on the Earth at a distance of 23°.5 from either poles.
hamârâhâ-ye qotbi (#)
Fr.: coordonnées polaires
A coordinate system in which the position of any point (M) in a plane is specified by two coordinates: 1) ρ, which expresses the distance from a fixed point (the pole, denoted O), and 2) the number φ, which is the angle formed by the line segment OM and a fixed reference line passing through the pole.
Fr.: cuspide polaire
ruz-e qotbi (#)
Fr.: jour polaire
In polar regions, the portion of the year when the Sun is continuously in the sky. Its length changes from twenty hours at the Arctic/Antarctic Circle (latitude 66°33' N or S) to 186 days at the North/South Pole.
Fr.: distance polaire
The angular distance of an object from a celestial pole. It is equal to 90° minus the object's declination.