- 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, ...
A cloud species the elements of which have the form of more or less isolated, generally smooth lenses or almonds; the outlines are sharp and sometimes show irisation. These clouds appear most often in formations of orographic origin, the result of lee waves, in which cases they remain nearly stationary with respect to the terrain (standing cloud), but they also occur in regions without marked orography. This species is found mainly in the genera cirrocumulus, altocumulus, and (rarely) stratocumulus. Altocumulus lenticularis differs from cirrocumulus lenticularis in that, when smooth and without elements, it has shadowed parts while the latter is very white throughout. When undulated or subdivided, the altocumulus species differs from stratocumulus lenticularis in that its elements subtend an angle of less than 5° when viewed at an angle of more than 30° above the horizon. See cloud classification.
Industry:Weather
The electric discharge that initiates each return stroke in a cloud- to-ground lightning discharge. It is a channel of high ionization that propagates through the air by virtue of the electric breakdown at its front produced by the charge it lowers. The stepped leader initiates the first stroke in a cloud-to-ground flash and establishes the channel for most subsequent strokes of a lightning discharge. The dart leader initiates most subsequent strokes. Dart-stepped leaders begin as dart leaders and end as stepped leaders. The initiating processes in cloud discharges are sometimes also called leaders but their properties are not well measured.
Industry:Weather
The electric discharge that initiates each return stroke in a cloud- to-ground lightning discharge. It is a channel of high ionization that propagates through the air by virtue of the electric breakdown at its front produced by the charge it lowers. The stepped leader initiates the first stroke in a cloud-to-ground flash and establishes the channel for most subsequent strokes of a lightning discharge. The dart leader initiates most subsequent strokes. Dart-stepped leaders begin as dart leaders and end as stepped leaders. The initiating processes in cloud discharges are sometimes also called leaders but their properties are not well measured.
Industry:Weather
A cloud variety characterized more by the appearance of the spaces between the cloud elements than by the elements themselves. The gaps are generally rounded and often have fringed edges. The overall appearance is that of a honeycomb or net, the negative of that of clouds composed of separate rounded elements. This variety is a modification mainly of the genera cirrocumulus and altocumulus and may apply to the species stratiformis, castellanus, or floccus. See cloud classification.
Industry:Weather
A cloud variety characterized more by the appearance of the spaces between the cloud elements than by the elements themselves. The gaps are generally rounded and often have fringed edges. The overall appearance is that of a honeycomb or net, the negative of that of clouds composed of separate rounded elements. This variety is a modification mainly of the genera cirrocumulus and altocumulus and may apply to the species stratiformis, castellanus, or floccus. See cloud classification.
Industry:Weather
An instrument combining a pulsed laser transmitter and optical receiver (usually a telescope) with an electronic signal processing unit used for the detection and ranging of various distant targets in the atmosphere, analogous to the principles of operation of microwave radar. Normally, the transmitter and receiver are coaligned and placed closely together to measure the laser energy backscattered by the target into the direction of the receiver. The use of lasers allows the light pulses to be exceptionally short, highly focused, and monochromatic, but laser light suffers from strong, range-limiting attenuation in many types of clouds. Depending on the spectral characteristics of the laser and detector and the number of receiver channels, a large variety of lidar applications for atmospheric research are in use. Simple one-channel laser ceilometers measure cloud-base heights and internal cloud structures; polarization lidars measure cloud phase and hydrometeor type; differential absorption (DIAL) and Raman lidars measure the concentrations of selected molecular species; high spectral resolution lidars (HSRL) measure the separation of molecular and aerosol or cloud constituents; and Doppler lidars measure the radial velocity of aerosol or cloud targets. Lidar wavelengths range from the near-ultraviolet to the midinfrared (≈0. 3–12 μm).
Industry:Weather
An instrument combining a pulsed laser transmitter and optical receiver (usually a telescope) with an electronic signal processing unit used for the detection and ranging of various distant targets in the atmosphere, analogous to the principles of operation of microwave radar. Normally, the transmitter and receiver are coaligned and placed closely together to measure the laser energy backscattered by the target into the direction of the receiver. The use of lasers allows the light pulses to be exceptionally short, highly focused, and monochromatic, but laser light suffers from strong, range-limiting attenuation in many types of clouds. Depending on the spectral characteristics of the laser and detector and the number of receiver channels, a large variety of lidar applications for atmospheric research are in use. Simple one-channel laser ceilometers measure cloud-base heights and internal cloud structures; polarization lidars measure cloud phase and hydrometeor type; differential absorption (DIAL) and Raman lidars measure the concentrations of selected molecular species; high spectral resolution lidars (HSRL) measure the separation of molecular and aerosol or cloud constituents; and Doppler lidars measure the radial velocity of aerosol or cloud targets. Lidar wavelengths range from the near-ultraviolet to the midinfrared (≈0. 3–12 μm).
Industry:Weather
A name for the sirocco in Spain. It is a hot, sand- and dust-laden wind from between southeast and southwest that blows in front of a depression on the southeast coast of Spain but extends only a few miles inland.
Industry:Weather
A moderate to gale-force southeasterly wind in the Persian Gulf; it is accompanied by gloomy weather, rain, and squalls. The kaus is most frequent between December and April. It is associated with the passage of a winter depression, and is often followed by a strong southwesterly wind, the suahili.
Industry:Weather
On the Bulgarian coast, a west wind that usually follows rain and persists for one to three days.
Industry:Weather
