- 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 the context of tangent linear and adjoint models, perturbations are considered small if their development can be described with acceptable accuracy by tangent linear equations. In many cases, this class of perturbations includes those that are comparable in magnitude to the typical analysis errors of operational forecast models. See tangent linear approximation.
Industry:Weather
In the Beaufort wind scale, a wind with a speed from 41 to 47 knots (47 to 54 mph) or Beaufort Number 9 (Force 9).
Industry:Weather
In the Beaufort wind scale, a wind with a speed from 22 to 27 knots (25 to 31 mph) or Beaufort Number 6 (Force 6).
Industry:Weather
In surface weather observations, a term used to denote one or more of the following: 1) the amount of sky covered but not necessarily concealed by clouds or by obscuring phenomena aloft; 2) the amount of sky concealed by obscuring phenomena that reach the ground; or 3) the amount of sky covered or concealed by a combination of 1) and 2). Opaque sky cover is the amount of sky completely hidden by clouds or obscuring phenomena, while total sky cover includes this plus the amount of sky covered but not concealed (transparent). Sky cover, for any level aloft, is described as thin if the ratio of transparent to total sky cover at and below that level is one-half or more. Sky cover is reported in tenths, so that 0. 0 indicates a clear sky and 1. 0 (or 10/10) indicates a completely covered sky. Amount of sky cover for any given level is determined according to the summation principle. The following classifications of sky cover are used in aviation weather observations: clear, scattered, broken, overcast, partial obscuration, obscuration.
Industry:Weather
In statistics, a group of observations selected from a statistical population by a set procedure. Samples may be selected at random or systematically. The sample is taken in an attempt to estimate the population. See random sample.
Industry:Weather
In spectral wave modeling, the contributions to net energy increase and decrease within each spectral band, due to such effects as energy input from the wind, nonlinear transfer of energy between different spectral components, energy dissipation by wave breaking, bottom stress, etc. These contributions do not include the spatial flux of energy due to wave propagation or the flux in wavenumber space due to changes in water depth or current.
Industry:Weather
In reference to conductivity near the ground, the primary source of ions in the lowest 1 or 2 km of the atmosphere above land. (Cosmic radiation is dominant over the oceans and at higher altitudes. )
The ionizing radiation can take the form of 1) emission of α, β, or γ radiation by radioactive materials in the soil; or 2) emission from gaseous radioactive daughter products (radon) that emanate from the soil. The α radiation emitted by materials in the ground is absorbed in the lowest few centimeters of the atmosphere, β radiation penetrates a few meters, and γ radiation a few hundred meters. The ionization produced by radioactive gases in the atmosphere is highly variable and depends on the rate of emission from the soil and also on atmospheric dispersion. <sup>222</sup>Rn, which has a half-life of 3. 8 days, is produced by the uranium decay series. <sup>220</sup>Rn (thoron) is produced by the thorium decay series and has a half-life of 54 seconds.
Industry:Weather
In radio and radar applications, a circuit that will resonate at a certain frequency, or over a range of frequencies, when properly excited. An important type of resonator is the cavity resonator, a closed hollow volume having conducting walls. The frequency at which such cavities resonate is a function of their volume and shape. They are used for making accurate frequency comparisons and for generating radio frequencies, usually in the microwave region.
Industry:Weather
