- 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, ...
1. In common meteorological usage, a line of equal or constant value of a given quantity, with respect to either space or time; same as isogram. 2. (Also called isarithm. ) A line drawn through points on a graph at which a given quantity has the same numerical value (or occurs with the same frequency) as a function of the two coordinate variables. Compare isotimic line. 3. A straight line along which lie corresponding values of a dependent and independent variable.
Industry:Weather
1. In chemistry, atoms or specific groupings of atoms that have gained or lost one or more electrons, as the “chloride ion” or “ammonium ion. ”
Ions are most familiar in aqueous solutions and in crystal structures, but they also exist in the gas phase at all altitudes in the atmosphere. They are most abundant, and have the greatest importance, in the ionosphere, between about 70 and 300 km in altitude. 2. In atmospheric electricity, any of several types of electrically charged submicroscopic particles normally found in the atmosphere. Atmospheric ions are of two principal types, small ions and large ions, although a class of intermediate ions has occasionally been reported. The ionization process that forms small ions depends upon two distinct agencies, cosmic rays and radioactive emanations. Each of these consists of very energetic particles that ionize neutral air molecules by knocking out one or more planetary electrons. The resulting free electron and positively charged molecule (or atom) very quickly attach themselves to one or, at most, a small number of neutral air molecules, thereby forming new small ions. In the presence of Aitken nuclei, some of the small ions will in turn attach themselves to these nuclei, thereby creating new large ions. The two main classes of ions differ widely in mobility. Only the highly mobile small ions contribute significantly to the electrical conductivity of the air under most conditions. The intermediate ions and large ions are important in certain space charge effects, but are too sluggish to contribute much to conductivity. The processes of formation of ions are offset by certain processes of destruction of the ions. See recombination, ion mobility.
Industry:Weather
1. Generally, some measure of the water vapor content of air. The multiplicity of humidity measures is partly due to different methods of measurement and partly because the conservative measures (mixing ratio, specific humidity) cover an extremely wide dynamic range, as a result of the rapid variation of saturation vapor pressure with temperature. 2. Popularly, same as relative humidity.
Industry:Weather
1. Delicate tufts of hoarfrost that occasionally form in great abundance on an ice or snow surface (surface hoar); it also forms as a type of crevasse hoar or window frost. 2. Formations of ice crystals on the surface of a quiet, slowly freezing body of water.
Industry:Weather
1. Bright sunshine duration: interval of time during which solar radiation is intense enough to cast distinct shadows. 2. Geographically or topographically possible sunshine duration: maximum interval of time during which solar radiation can reach a given surface. 3. Maximum possible sunshine duration: interval of time between the rising and setting of the upper limb of the sun.
Industry:Weather
1. Aspect of hydrologic processes and phenomena, such as precipitation, streamflow (stage), etc. 2. In hydrologic modeling, an area with similar hydrologic properties (soil, vegetation, etc. ).
Industry:Weather
1. Any wave motion in which no form of energy other than kinetic energy is present. In this general sense, Helmholtz waves, barotropic disturbances, Rossby waves, etc. , are inertia waves. 2. More restrictedly, a wave motion in which the source of kinetic energy of the disturbance is the rotation of the fluid about some given axis. In the atmosphere a westerly wind system is such a source, the inertia waves here being, in general, stable. A similar analysis has been applied to smaller vortices, such as the hurricane. See inertial instability.
Industry:Weather
1. Any integral multiple of the lowest (or fundamental) frequency of a physical system. For example, the motion of a taut, gently plucked violin string is the superposition of sinusoidal motions with frequencies ω0, ω1 = 2ω0, ω2, 3ω0,. . . Where ω0 is the fundamental frequency and ω1, ω2,. . . Are the harmonics (or overtones), resulting in a harmonious composite sound. 2. A sine or cosine component of the Fourier series representation of an empirical or theoretical function.
Industry:Weather
1. An older reference to the Greenland Ice Sheet. 2. Same as land ice, particularly the more interior portions of an ice sheet.
Industry:Weather
1. A statistical method for determining the amplitude and period of certain harmonic or wave components in a set of data with the aid of Fourier series. Harmonic analysis has been used in meteorology, for example, to determine periodicities in climatic data (Conrad 1950); to determine the wavelengths most strongly represented in general circulation flow patterns; and to determine the spectrum of turbulent eddies (Sutton 1953). 2. The representation of tidal variations as the sum of several harmonics, each of different period, amplitude, and phase. The periods fall into three tidal species: long period, diurnal, and semidiurnal. Each tidal species contains groups of harmonics that can be separated by analysis of a month of observations. In turn, each group contains constituents that can be separated by analysis of a year of observations. In shallow water, harmonics are also generated in the third-diurnal, fourth-diurnal, and higher species. These constituents can be used for harmonic prediction of tides.
Industry:Weather
