- 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, ...
In statistical terminology, a collection of quantities having a normal distribution.
Industry:Weather
A method that uses model normal modes to adjust the initial conditions of an NWP model so that high-frequency oscillations are removed from the subsequent forecast. The most successful procedure is known as nonlinear normal mode initialization, in which the normal modes are used to filter out high frequencies from the time derivative of the initial conditions.
Industry:Weather
A number by which the performance of a radio receiver can be specified. Essentially, the noise figure is the ratio of the noise generated by the actual receiver to the noise output of an “ideal” receiver with the same overall gain and bandwidth when the receivers are connected to a room temperature load. The noise power from a simple load is equal to ''kTB'', where ''k'' is Boltzmann's constant; ''T'' the absolute temperature of the load, for example, resistor; and ''B'' the measurement bandwidth. See also noise level, signal-to-noise ratio.
Industry:Weather
In meteorology, any chart that shows the distribution of the official normal values of a meteorological element. Compare mean chart.
Industry:Weather
A barometer of such accuracy that it can be used for the determination of pressure standards. An instrument such as a large-bore mercury barometer is usually used as a normal barometer.
Industry:Weather
The complete renewal of soil air to a depth of 20 cm about once each hour.
Industry:Weather
1. Referring to a normal distribution. 2. Regular or typical in the sense of lying within the limits of common occurrence, but sometimes denoting a unique value, as a measure of central tendency. Either sense presupposes a stable probability distribution. 3. As usually used in meteorology, the average value of a meteorological element over any fixed period of years that is recognized as a standard for the country and element concerned. Often erroneously interpreted by the general public as meaning the weather patterns that one should expect. In the broadest sense, “normals” should consist of a suite of descriptive statistics, including measures of central tendency (e.g., mean, median), range (e.g., standard deviation, interquartile range, extremes), variation, and frequency of occurrence. At the International Meteorological Conference at Warsaw in 1935, the years 1901–30 were selected as the international standard period for normals. Recommended international usage is to recalculate the normals at the end of every decade using the preceding 30 years. This practice is used to take account of the slow changes in climate and to add more recently established stations to the network with observed normals. Normals should be based on actual observations if available; otherwise a recognized method should be used to “reduce” shorter series to the normal period by comparison with neighboring stations. Recognized methods of adjusting for inhomogeneities should be used to account for breaks or gradual changes introduced into the data record by changes in the hours of observation, in the observational practices, in the site or instruments used, or by a gradual change in the character of the surrounding country, such as the growth of a city. The years covered by a normal should always be clearly stated, since averages for different periods of the same length are rarely the same. See climatological standard normals.
Industry:Weather
The fluid in a pair of immiscible fluids that has a contact angle with the solid surface greater than 90°. It is the fluid with the lower affinity for the solid surface.
Industry:Weather
A tornado that occurs with a parent cloud in its growth stage and with its vorticity originating in the boundary layer. The parent cloud does not contain a preexisting midlevel mesocyclone. Landspouts and gustnadoes are examples of the nonsupercell tornado.
Industry:Weather
