- Industry: 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, ...
The local variation of a velocity vector in a given direction. In oceanography, this frequently refers to the variation of the ocean current with depth. See Also shear flow.
Industry:Weather
The local rate of change of a vector or scalar quantity with time at a given point in space. Thus, in symbols, ∂''p''/∂''t'' is the pressure tendency, ∂ζ/∂''t'' is the vorticity tendency, etc. Because of the difficulty of measuring instantaneous variations in the atmosphere, variations are usually obtained from the differences in magnitudes over a finite period of time and the definition of tendency is frequently broadened to include the local time variations so obtained. An example is the familiar three-hourly pressure tendency given in surface weather observations; in fact, the term “tendency” alone often means the pressure tendency.
Industry:Weather
The line connecting the total head at different points along the flow.
Industry:Weather
The level at which the wind speed reaches a maximum or minimum (including zero) in a vertical profile of wind; analogous to the tropopause in a vertical profile of temperature.
Industry:Weather
The level above which sound intensity, at any specified frequency, must rise in order to be detected by the average human ear. This threshold value decreases with increasing frequency from a value of about one microwatt m<sup>−2 </sup>at 50 Hz to slightly less than 10<sup>−6</sup> microwatts m<sup>−2</sup> at about 2000 Hz, and then increases with increasing frequency to about 10<sup>4</sup> microwatt m<sup>−2</sup> near 30 000 Hz. As the sound intensity rises above the threshold of audibility at any frequency, continued increase will finally raise the intensity to a second type of limit, the threshold of pain (threshold of discomfort, threshold of feeling). This threshold is rather insensitive to frequency, being found at about 10<sup>6</sup> microwatts m<sup>−2</sup> for nearly all frequencies in the audible range. It represents the limit above which appreciable increase in sound intensity will lead to sensible pain in the average human ear. See decibel.
Industry:Weather
The lesser dry season, made up of a few weeks of hot dry weather, that breaks up the summer rainy season on the Pacific coast of Mexico and Central America. See verano.
Industry:Weather
The layer of air in the urban canopy beneath the mean height of the buildings and trees. Its climate is dominated by microscale processes due to the complex array of surfaces (their orientation, albedo, emissivity, thermal properties, wetness, etc. ). It is a zone of multiple reflection and emission, wakes and vortices, especially in the urban canyons. Compare urban boundary layer.
Industry:Weather
The latitudes occupied by the trade winds, generally between about 30° in the winter hemisphere and 35° in the summer hemisphere.
Industry:Weather
The kinetic energy of flow per unit weight of flowing liquid. (''h<sub>v</sub>'' = ''v''<sup>2</sup>/2''g'', where ''v'' is the flow velocity and ''g'' is the acceleration of gravity. )
Industry:Weather
