- 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 return propagation of charge along a channel in a cloud in response to the initial breakdown streamer contacting a region of opposite charge. In this context it can be viewed as a small return stroke in the cloud. See K changes.
Industry:Weather
The series of electrical processes taking place within 1 s by which charge is transferred along a discharge channel between electric charge centers of opposite sign within a thundercloud (intracloud flash), between a cloud charge center and the earth's surface (cloud- to-ground flash or ground-to-cloud discharge), between two different clouds (intercloud or cloud-to-cloud discharge), or between a cloud charge and the air (air discharge). It is a very large-scale form of the common spark discharge. A single lightning discharge is called a lightning flash.
Industry:Weather
The side of a mountain, ridge, or other flow obstacle away from the large-scale or ridge- top flow direction; the downwind side; opposite of windward.
Industry:Weather
The relatively dark appearance of the underside of a cloud layer when it is over land that is not snow covered. This term is used largely in polar regions with reference to the sky map; land sky is brighter than water sky, but is much darker than ice blink or snow blink.
Industry:Weather
The ratio of the volume backscattering coefficient to the volume extinction coefficient of a scattering medium. If this ratio is known or can be assumed, it facilitates inverting the lidar equation to solve for the profile of the extinction coefficient in terms of the measured power.
Industry:Weather
The ratio of the radiant energy sensed by the average human eye at a particular wavelength to that received. This ratio reaches a maximum inside the visible portion of the spectrum and falls to zero outside it. Luminous efficiency is dimensionless but is often given the units of lumens per watt. Photometric quantities are obtained by multiplying the corresponding radiometric quantities by the luminous efficiency and so often bear the adjective luminous, for example, luminous flux. However, when the radiometric quantities, radiance and irradiance, are transformed into photometric ones, they are given the special names luminance and illuminance. The luminous efficiency of cones differs from that of rods.
Industry:Weather
The ratio of the mass of liquid water to the mass of dry air in a unit volume of air. Units are mass of liquid water per mass of dry air, such as g kg−1. Compare mixing ratio, total water mixing ratio.
Industry:Weather
The proportionality factor in the lidar equation, usually represented by C, relating the power returned from a given range to the properties of the scattering medium. The lidar constant depends on characteristics of the particular lidar system including the transmitted power, pulse length, and receiver aperture. See lidar equation.
Industry:Weather
The proportionality constant α in Kolmogorov theory, which states that the spectral energy S in the inertial subrange is S = αε2/3k−5/3, for ε representing the viscous dissipation rate of turbulence kinetic energy, and k the wavenumber (inversely proportional to the wavelength or eddy size). Measurements of the 1D longitudinal spectrum of the wind in the planetary boundary layer show that this constant is equal to about 0. 5.
Industry:Weather
