- 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, ...
Free radical, formula NO<sub>3</sub>, formed from the reaction of nitrogen dioxide with ozone. NO<sub>3</sub> has a very strong optical absorption in the visible portion of the spectrum. Absorption of solar radiation in this region leads to photodissociation and thus a very short atmospheric lifetime during the day. However, at night NO<sub>3</sub> can build up to substantial levels and react with some families of organic molecules, allowing oxidation chemistry that would not otherwise occur at night. Nitrate reacts to form dinitrogen pentoxide, which can be taken up into aqueous droplets and increase acidity. Optical absorption has been used to detect NO<sub>3</sub> in the atmosphere.
Industry:Weather
Any chemical compound containing ONO<sub>2</sub>. These can be either organic nitrates (e.g., CH<sub>3</sub>ONO<sub>2</sub>) or inorganic nitrates (eg. , ClONO<sub>2</sub>). See also nitrate ion, nitrate radical.
Industry:Weather
The ionized form of nitric acid in solution, formula NO<sub>3</sub><sup>−</sup>. Nitrate is a common, if not universal, component of rainwater and is often used as a marker for acid precipitation, since its production is usually associated with combustion sources. It is an important plant nutrient.
Industry:Weather
A remote indicator for wind speed and direction used in conjunction with a contact anemometer and a wind vane. The indicator consists of a center light, connected to the contact anemometer, surrounded by eight equally spaced lights that are individually connected to a set of similarly spaced electrical contacts on the wind vane. Wind speed is determined by counting the number of flashes of the center wind vane during an interval of time. Direction, indicated by the position of the illuminated outer bulbs, is given to 16 points of the compass.
Industry:Weather
Former name for any rain-producing cloud. It is not now recognized in the international cloud classification.
Industry:Weather
A principal cloud type (cloud genus), gray colored and often dark, rendered diffuse by more or less continuously falling rain, snow, sleet, etc. , of the ordinary varieties and not accompanied by lightning, thunder, or hail. In most cases the precipitation reaches the ground, but not necessarily. Nimbostratus is composed of suspended water droplets, sometimes supercooled, and of falling raindrops and/or snow crystals or snowflakes. It occupies a layer of large horizontal and vertical extent. The great density and thickness (usually many thousands of feet) of this cloud prevent observation of the sun; this, plus the absence of small droplets in its lower portion, gives nimbostratus the appearance of dim and uniform lighting from within. It also follows that nimbostratus has no well-defined base, but rather a deep zone of visibility attenuation. Frequently a false base may appear at the level where snow melts into rain. Nimbostratus usually results from the thickening of altostratus to the point where the sun becomes totally indiscernible (Ns altostratomutatus); this point in time usually coincides with the beginning of relatively continuous precipitation. Rarely, it may evolve in like manner from stratocumulus or altocumulus (Ns stratocumulomutatus or Ns altocumulomutatus). Nimbostratus sometimes forms by the spreading of cumulonimbus or cumulus congestus when these clouds produce rainfall (Ns cumulonimbogenitus or Ns cumulogenitus). By definition, nimbostratus is always accompanied by the complementary features praecipitatio or virga. The accessory cloud, pannus, also is a common feature. At first the pannus consists of separate units, but later they may merge into a continuous layer and extend upward into the nimbostratus. Nimbostratus is most easily confused, in identification, with thick masses of altostratus, stratus, or stratocumulus. Altostratus, however, is lighter in color, appears less uniform from below, and does not completely hide the sun. In case of further doubt, a cloud is called nimbostratus if precipitation from it reaches the ground. Stratus also may have precipitation, but only of very small-sized particles. Stratocumulus shows clear relief and a well-defined limit of its base. See cloud classification.
Industry:Weather
A thin elastic crust of ice up to 10 cm thick that, under pressure, may deform by finger rafting.
Industry:Weather
Dry squalls that occur at night in southwest Africa and the Congo. It is likely that this term is loosely applied to other diurnal local winds such as mountain wind, land breeze, midnight wind, etc.
Industry:Weather
In hydrodynamic instability theory, a wave solution the amplitude of which does not change with time; it neither grows nor decays. In contrast, the amplitude of a growing mode (or wave) increases with time; that of a decaying mode (or wave) decreases with time. The latter two are unstable waves.
Industry:Weather
A unit of force that, when applied to a body of mass one kilogram, gives it an acceleration of one meter per second squared (1 N = 1 kg m s<sup>−2</sup>).
Industry:Weather
