- 行业: Weather
- Number of terms: 60695
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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, ...
The shortest navigational distance between two points on the earth's surface. The great circle is a direct route.
Industry:Weather
A turbulence closure scheme proposed by Kraichnan that eliminates the nonlocal direct interaction between large-scale and small-scale turbulence components.
Industry:Weather
A closed thermal circulation in a vertical plane in which the rising motion occurs at higher potential temperature than the sinking motion. Such a cell converts heat energy to potential energy and then to kinetic energy. The importance of such cells in the atmosphere, in particular the subtropical and equatorial circulation, is much discussed in theories of the general circulation. It has also been suggested that the tropical cyclone is essentially a direct cell. See indirect cell.
Industry:Weather
1. Without qualification usually means electric dipole, a system composed of two charges of equal and opposite sign separated by a distance. A magnetic dipole is an electric current loop enclosing a finite area in a plane. See dipole moment. 2. Same as dipole antenna.
Industry:Weather
Without qualification usually means electric dipole moment, the product of charge and separation distance of an (electric) dipole. Dipole moment is a vector, its direction determined by the position vector from the negative to the positive charge. Dipole moments (usually of molecules) are classified as permanent (the centers of positive and negative charge do not coincide even when subjected to no external field) and induced (charge separation is a consequence of an external field acting in opposite directions on positive and negative charges). Water is often given as the prime example of a molecule with a permanent dipole moment. The magnetic dipole moment of a magnetic dipole is the product of the electric current in the loop and the area it encloses. Magnetic dipole moment also is a vector, its direction determined by the normal to the plane of the current loop, the sense of this normal specified by the right-hand rule.
Industry:Weather
An instrument for measuring the inclination of the earth's magnetic field. In its simplest form it consists only of a magnetized needle mounted on a pointed bearing, and a protractor. By timing the oscillation of the needle, it is possible to obtain, also, relative values of the intensity of the earth's magnetic field.
Industry:Weather
The rate of change of water content with soil water pressure. Its value will depend on whether volumetric or gravimetric water content is used and how pressure is expressed.
Industry:Weather
Solid-state laser in which lasing is achieved by passing an injection current through the active region of a semiconductor across the p–n junction. Operating in the infrared spectral region, 2. 7–30 μm, makes diode lasers particularly useful for the measurement of certain atmospheric trace gases such as nitrous oxide, carbon monoxide, or formaldehyde.
Industry:Weather
Dioxygenated cyclic organic compound, formula C4H8O2, formally a cyclohexane structure in which two diametrically opposed CH2 groups have been replaced by oxygen atoms. Dioxane is widely used as a solvent and as a stabilizer in paints, varnishes, etc; thought to be carcinogenic. Not to be confused with dioxins, formed in the combustion of chlorinated hydrocarbons.
Industry:Weather
A type of antenna for transmitting or receiving electromagnetic radiation, most often in the radio frequency band. The term dipole antenna has no necessary connection with dipole radiation in the sense usually meant in electromagnetic theory but arises from configuration: A dipole antenna is essentially two thin (diameter much less than length) conductors or poles separated by a gap by means of which an oscillating electric current is fed into (or out of) them. If the total length of the two poles is much less than the wavelength of their radiation, the dipole antenna is sometimes called a short dipole, the source of the term dipole radiation (radiation from an ideal oscillating dipole of negligible extent). Sometimes dipole antenna means an antenna with a length of half the wavelength, but a more precise term is half-wave dipole. The defining characteristic of a dipole antenna is its two identical components, not its length.
Industry:Weather
