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.
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.
varunâ-ye kore-yi, ~ sepehri
Fr.: latitude sphérique
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.
Fr.: miroir sphérique
spherical polar coordinate
hamârâhâ-ye kore-yi-ye qotbi
Fr.: coordonnées sphériques polaires
Same as → spherical coordinates.
Fr.: symétrie sphérique
A configuration in which the constituting parts are arranged concentrically around the center of a sphere.
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.
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.
Shaped like a → spheroid.
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.
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.
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 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.
Fr.: phase stationnaire
Mechanics: The condition of a body or system at rest.
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.
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.
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 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.
Fr.: photométrie stellaire
The precise measurement of a star's brightness, usually through several specific wavelength bands.
fizik-e setâre-yi (#)
Fr.: physique stellaire
Same as → stellar astrophysics.