- 行业: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
Term used to denote the injection of energetic electrons usually along magnetic field lines into the upper atmosphere from the magnetosphere or directly from the sun.
Industry:Weather
The number of electrons per unit volume of a substance. Often applied in a restricted sense to free electrons.
Industry:Weather
The process in which a relatively small number of free electrons in a gas that is subjected to a strong electric field accelerate, ionize gas atoms by collision, and thus form new electrons to undergo the same process in cumulative fashion. All streamers in a lightning discharge propagate by formation of electron avalanches in the regions of high electric field strength that move ahead of their advancing tips. Particularly in the case of the intense return streamer, avalanche processes are enhanced by formation of photoelectrons as a result of ultraviolet radiation emitted by the excited molecules in the region just behind the tip. An avalanche cannot possibly begin until the local electric field strength is high enough to accelerate a free electron to the minimum ionizing speed in the space and time interval corresponding to one mean free path of the electron, for upon collision, the electron usually loses its forward motion in the direction of the field. Maintenance of an avalanche requires a large reservoir of charge, such as accumulates more or less periodically in active thunderstorms.
Industry:Weather
A detector used in a gas chromatograph that operates by sensing a decrease in the number of free electrons in the detector cavity due to their capture by electrophilic compounds eluting from the column of the chromatograph. The free electrons are produced by beta decay of a radioactive isotope (e.g., 63Ni, half-life 92 years) in the detector cavity.
Industry:Weather
A stream of electrons confined and focused by a magnetic field. In a cathode-ray tube (CRT), the electron beam is scanned across the tube's phosphorescent surface, as it is modulated in intensity, to produce a visual image. The beam emanates from the tube's cathode and is the cathode ray.
Industry:Weather
The negatively charged subatomic particle with charge 1. 60218 x 10−19 coulombs and rest mass 9. 10939 x 10−31 kg. Each element in the periodic table is characterized by a fixed number of electrons orbiting a much heavier nucleus. The mass of the electron is about 1/1836 that of the proton. See free electron, beta particle.
Industry:Weather
An instrument for measuring differences of electric potential. See unifilar electrometer, bifilar electrometer, capillary electrometer, quadrant electrometer, vacuum-tube electrometer; compare electroscope.
Industry:Weather
The branch of physics primarily concerned with the group of forces associated with electric charges.
Industry:Weather
An oscillation of the electric or magnetic field associated with the propagation of electromagnetic radiation. Electromagnetic waves are characterized by their wavelength or wavenumber, amplitude, and polarization characteristics. They propagate at the speed of light.
Industry:Weather
The ordered sequence of all known electromagnetic radiations, extending from the shortest cosmic rays through gamma rays, x-rays, ultraviolet radiation, visible radiation, infrared radiation, and including microwave and all other radio wavelengths. The division of this continuum of wavelengths (or frequencies) into a number of named subportions is rather arbitrary and, with one or two exceptions, the boundaries of the several subportions are only vaguely defined. Nevertheless, to each of the commonly identified subportions there correspond characteristic types of physical systems capable of emitting radiation at those wavelengths. Thus, gamma rays are emitted from the nuclei of atoms as they undergo any of several types of nuclear rearrangements; visible light is emitted, for the most part, by atoms with planetary electrons undergoing transitions to lower energy states; infrared radiation is associated with characteristic molecular vibrations and rotations; and radio waves, broadly speaking, are emitted by virtue of the accelerations of free electrons in metals as, for example, the moving electrons in a radio antenna wire.
Industry:Weather
