- 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, ...
1. The study of the microclimate in the air space occupied by plant communities within the canopy, on the surfaces of the plants themselves, and, in some cases, in air spaces within the plants. 2. The study of climatic regions defined largely by distribution of plant species.
Industry:Weather
1. The process by which electromagnetic radiation is propagated through free space. The propagation takes place at the speed of light (3. 00 x 10<sup>8</sup> m s<sup>−1</sup> in vacuum) by way of joint (orthogonal) oscillations in the electric and magnetic fields. This process is to be distinguished from other forms of energy transfer such as conduction and convection. 2. Propagation of energy by any physical quantity governed by a wave equation. 3. See alpha ray, beta ray.
Industry:Weather
1. The region of poor and intermittent rains south of the Sahara Desert in Africa. 2. A strong dust-bearing desert wind in Morocco.
Industry:Weather
1. The previous value in a time series. Thus, if ''x''(''t'') denotes the present value, the value of persistence would be ''x''(''t'' − 1), whence the latter value is regarded as “persisting. ” It is used as an objective standard in the verification of weather forecasts. Sometimes it is extended to mean ''x''(''t'' − ''h'') where ''h'' is arbitrary. 2. (Also called constancy, steadiness. ) With respect to the long-term nature of the wind at a given location, the ratio of the magnitude of the main wind vector to the average speed of the wind without regard to direction. 3. (Also called inertial forecast. ) In general, the tendency for the occurrence of a specific event to be more probable, at a given time, if that same event has occurred in the immediately preceding time period.
Industry:Weather
1. The power averaged over that carrier-frequency cycle that occurs when the power is maximum (usually one-half the maximum instantaneous power). In radar, the transmitted power averaged over one cycle of the carrier at the position in the pulse where the power is at a maximum. For typical weather radars, the peak power is in the range from several kilowatts to a megawatt.
Industry:Weather
1. The popular term for arcus. 2. A low-level, horizontal, tube-shaped arcus cloud associated with a gust front of a convective storm (or occasionally a cold front). Roll clouds are relatively rare; they are completely detached from the convective storm's cloud base, thus differentiating them from the more familiar shelf clouds. Roll clouds appear to be rolling about a horizontal axis because of the shearing effects and horizontal vorticity provided by the differing air masses. See'' also'' rotor cloud, morning glory.
Industry:Weather
1. The oscillation of a body of water at its natural period. Coastal measurements of sea level often show seiches with amplitudes of a few centimeters and periods of a few minutes due to oscillations of the local harbor, estuary, or bay, superimposed on the normal tidal changes. 2. In the Great Lakes area of the United States, any sudden rise in the water of a harbor or a lake, whether or not it is oscillatory. Although inaccurate in a strict sense, this usage is well established in the Great Lakes area.
Industry:Weather
1. The mass of suspended particulate aerosols per mass or volume of air. 2. A measure of the amount of mass of particulates per unit time that activities in a region generate in the atmosphere. If a simple “box model” is used to estimate the associated particulate concentration, the result is proportional to the total emission rate and is inversely proportional to the wind speed and the vertical cross-sectional area of the airflow through a plane perpendicular to the wind.
Industry:Weather
1. The four physical laws or equations that are most commonly used to explain the emission of radiation: 1) Kirchhoff's law; 2) Planck's law; 3) Stefan–Boltzmann law; and 4) Wien's displacement law. Of these, 1) and 2) are fundamental. The remaining two can be derived from 2). 2. All of the more inclusive assemblage of empirical and theoretical laws describing all manifestations of radiative phenomena, for example, Bouguer–Lambert law, Lambert's law, Stefan– Boltzmann law, etc.
Industry:Weather
1. The decrease in streamflow, at a point along a stream channel, following the passage of a crest. 2. (Also called falling limb. ) That portion of a hydrograph that shows the rate of decrease of stage or discharge following the passage of a crest; the opposite of rising limb.
Industry:Weather
