- 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, ...
The angular momentum as measured in an absolute coordinate system; hence, the vector product of the position vector of a particle into the absolute momentum of the particle.
In the atmosphere the absolute angular momentum M per unit mass of air is equal to the sum of the angular momentum relative to the earth and the angular momentum due to the rotation of the earth:
<br><center>[[File:ams2001glos-Ae1.gif
Industry:Weather
Velocity as measured in an absolute coordinate system; hence, in meteorology, the (vector) sum of the velocity of a fluid parcel relative to the earth and the velocity of the parcel due to the earth's rotation.
The east–west component is the only one affected:
<center>[[File:ams2001glos-Ae3.gif
Industry:Weather
The vorticity of a fluid particle determined with respect to an absolute coordinate system.
The absolute vorticity vector is defined by 2Ω + ∇ × u, where Ω is the earth's angular velocity vector and u is the three-dimensional relative velocity vector. 2. The vertical component η of the absolute vorticity vector (as defined above) given by the sum of the vertical component of the vorticity with respect to the earth (the relative vorticity) ζ and the vorticity of the earth (equal to the Coriolis parameter) ''f'':
<center>[[File:ams2001glos-Ae4.gif
Industry:Weather
The rate of change with time of the velocity vector of a particle.
If '''u''' is the vector velocity, the acceleration may be written as ''D'''''u'''''/Dt'', where ''D/Dt'' is the material (or total) derivative. For most purposes in hydrodynamics where Eulerian coordinates are employed, the acceleration is decomposed as follows:
<center>[[File:ams2001glos-Ae5.gif
Industry:Weather
The total cooling since the time in the evening when the turbulent heat flux near the ground produces a net heat flow from the earth to the atmosphere; used to measure or predict evolution of the stable boundary layer.
It is defined as the integral of the surface kinematic heat flux [[File:ams2001glos-Aex01.gif
Industry:Weather
A device to measure air temperature based on the principle that the speed of sound varies as the square root of temperature.
The most common application is in so-called sonic anemometers, where the time-of-flight of sound pulses between a pair of acoustic transducers is used to determine the speed of sound. This measurement is converted to temperature via the formula
<center>[[File:ams2001glos-Ae7.gif
Industry:Weather
A model atmosphere characterized by a dry-adiabatic lapse rate throughout its vertical extent.
Such a condition is never observed and is also rather poorly designated, since “adiabatic” represents a process, not a condition. The pressure in an adiabatic atmosphere decreases with height according to
<center>[[File:ams2001glos-Ae8.gif
Industry:Weather
The process of transport of an atmospheric property solely by the mass motion (velocity field) of the atmosphere; also, the rate of change of the value of the advected property at a given point.
Advection may be expressed in vector notation by
<center>[[File:ams2001glos-Ae9.gif
Industry:Weather
Sound, usually in the band of audible frequencies, associated with wake-eddy, vortex- produced pressure fluctuations resulting from air flow around obstacles, such as wires and twigs.
Although many such sounds are irregular noises, other familiar sounds involve fairly clear musical notes or humming sounds. The latter sounds were called aeolian tones by Rayleigh. Their pitch is controlled by the frequency with which eddies are formed and detached in the wake region on the lee side of the obstacle. The tones produced by wind flowing over a cylinder, including stretched wire, were shown by Strouhal in 1878 to be of frequency (pitch) ''f'' given by
<center>[[File:ams2001glos-Ae11.gif
Industry:Weather
The height above the displacement plane at which the mean wind becomes zero when extrapolating the logarithmic wind- speed profile downward through the surface layer.
It is a theoretical height that must be determined from the wind-speed profile, although there has been some success at relating this height to the arrangement, spacing, and physical height of individual roughness elements such as trees or houses. The average wind speed [[File:ams2001glos-Aex02.gif
Industry:Weather
