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spherical geometry hendese-ye kore-yi Fr.: géométrie sphérique The branch of geometry that deals with figures on the surface of a sphere (such as the spherical triangle and spherical polygon). It is an example of a non-Euclidean geometry. |
spherical harmonic hamâhang-e kore-yi Fr.: fonction harmonique sphérique A solution of some mathematical equations when → spherical polar coordinates are used in investigating physical problems in three dimensions. For example, solutions of → Laplace's equation treated in spherical polar coordinates. Spherical harmonics are ubiquitous in atomic and molecular physics and appear in quantum mechanics as → eigenfunctions of → orbital angular momentum. They are also important in the representation of the gravitational and magnetic fields of planetary bodies, the characterization of the → cosmic microwave background anisotropy, the description of electrical potentials due to charge distributions, and in certain types of fluid motion. The term spherical harmonics was first used by William Thomson (Lord Kelvin) and Peter Guthrie Tait in their 1867 Treatise on Natural Philosophy; → spherical; → harmonic. |
spherical latitude varunâ-ye kore-yi, ~ sepehri Fr.: latitude sphérique The angle between the → normal to a spherical reference surface and the → equatorial plane. |
spherical lens adasi-ye kore-yi Fr.: lentille sphérique A lens with a refractng surface which is a portion of a sphere. Spherical lenses can be of various types: → biconvex, → biconcave, → plano-convex, → plano-concave, → concavo-convex, and → convexo-concave. |
spherical mirror âyene-ye kore-yi Fr.: miroir sphérique A mirror whose reflecting surface is a portion of a sphere. Spherical mirrors can be of two types: → concave mirror and → convex mirror. |
spherical polar coordinate hamârâhâ-ye kore-yi-ye qotbi Fr.: coordonnées sphériques polaires Same as → spherical coordinates. → spherical; → polar; → coordinate |
spherical symmetry hamâmuni-ye kore-yi Fr.: symétrie sphérique A configuration in which the constituting parts are arranged concentrically around the center of a sphere. |
spherical triangle sebar-e kore-yi Fr.: triangle sphérique A triangle drawn on the → surface of a → sphere. A spherical triangle, like a plane triangle, may be right, obtuse, acute, equilateral, isosceles, or scalene. The sum of the angles of a spherical triangle is greater than 180° (π) and less than 540° (3π). See also → spherical excess. |
spheroid korevâr Fr.: sphéroïde A body that is shaped like a sphere but is not perfectly round, especially an ellipsoid that is generated by revolving an ellipse around one of its axes. |
spheroidal korevâr (#) Fr.: sphéroïdal Shaped like a → spheroid. |
spherule guyel Fr.: sphérule Any of many vitrified droplets of rock formed by the solidification of molten meteoritic material that flows off a meteorite during its passage through the Earth's atmosphere. Sizes range typically from 10 to 200 microns. "Small sphere," from → sphere + diminutive suffix → -ule. Guyel "small globe," from guy "ball, sphere" (variants golulé, gullé, goruk, gulu, gudé; 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") + -el diminutive suffix, → -ule. |
standard atmosphere havâsepehr-e estândé (#), javv-e ~ (#) Fr.: atmosphère standard A hypothetical vertical distribution of atmospheric temperature, pressure, and density that, by international agreement, is taken to be representative of the atmosphere for purposes of pressure altimeter calibrations, aircraft performance calculations, aircraft and missile design, ballistic tables, etc. → standard; → atmosphere. |
standard model of particle physics model-e estânde-ye fizik-e zarre-yi Fr.: modèle standard de la physique des particules The theory developed since the 1970s, which is based on the theories and discoveries since the 1930s, and aims at explaining the fundamental structure of matter. According to the standard model, everything in the universe is made from a few basic building blocks called fundamental particles, governed by four fundamental forces. The particles occur in two basic types, called quarks and leptons. Three of the four fundamental forces (except gravity) and their carrier particles are included in the Standard Model. The Standard Model has successfully explained almost all experimental results and precisely predicted a wide variety of phenomena. Over time and through many experiments, the Standard Model has become established as a well-tested physics theory. |
stationary phase fâz-e istvar Fr.: phase stationnaire Mechanics: The condition of a body or system at rest. → stationary; → phase. |
statistical physics fizik-e âmâri (#) Fr.: physique statistique The branch of physics that applies methods of → probability theory and → statistics to the behavior of large numbers of microscopic particles (such as molecules, atoms, or subatomic particles) in order to explain and predict the overall properties of the system composed of such particles. → statistical; → physics. |
stellar astrophysics axtarfizik-e setâre-yi Fr.: astrophysique stellaire The field of → astrophysics concerned with the study of the physical characteristics of stars, more specifically their → internal structure, physical processes taking place in their interiors, atmospheres, → stellar winds, → mass loss, interaction with the → interstellar medium, as well as the physical laws governing → star formation. Same as → stellar physics and → stellar astronomy. → stellar; → astrophysics. |
stellar atmosphere javv-e setâre-yi, havâsephre ~ Fr.: atmosphère stellaire The outer envelope of gas and plasma that surrounds a star; characterized by pressure, temperature, density, chemical composition, and opacity at varying altitudes. → stellar; → atmosphere. |
stellar atmosphere model model-e javv-e setâré Fr.: modèle d'atmosphère stellaire A model that computes the radiation field crossing the boundary layers of a star at all frequencies. The parameters used for the characterization of a stellar atmosphere model are: → effective temperature, → surface gravity, and → metallicity. → stellar; → atmosphere; → model. |
stellar photometry nursanji-ye setâre-yi Fr.: photométrie stellaire The precise measurement of a star's brightness, usually through several specific wavelength bands. → stellar; → photometry. |
stellar physics fizik-e setâre-yi (#) Fr.: physique stellaire Same as → stellar astrophysics. |
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