- 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 radar echo associated with a severe thunderstorm, the portion of the echo that is located above the weak-echo region on the low-altitude inflow side of the storm. The overhang consists of precipitation particles diverging from the storm's summit that descend as they are carried downwind. If the storm echo develops a bounded weak-echo region, it is found within the echo overhang.
Industry:Weather
1. The brightness or brilliance of an echo as it appears on an intensity-modulated display. 2. Less commonly, the intensity of the target signal.
Industry:Weather
A trace through points of equal signal intensity on a radar display. The properties of echo contours are not standardized. For example, the contour intervals may be fixed or variable, may be corrected for range or for various sources of attenuation, and may be averaged in time. See isoecho.
Industry:Weather
Ambiguous term that could denote 1) the fluctuation rate of the echo amplitude, or 2) the Doppler frequency of the target signal.
Industry:Weather
In radar, a general term for the appearance, on a radar display, of the radio signal scattered or reflected from a target. The characteristics of a radar echo are determined by 1) the waveform, frequency, and power of the incident wave; 2) the range and velocity of the target with respect to the radar; and 3) the size, shape, and composition of the target. See also target signal, blip.
Industry:Weather
1. The amplitude of the vertical deflection of an echo on an A-display. 2. Less commonly, the amplitude of the target signal.
Industry:Weather
A type of electronic instrument used to test and adjust radar equipment. It operates on the principle of a cavity resonator. A small amount of electromagnetic energy from the transmitting antenna is fed into a small cavity (or box), the volume of which can be adjusted to resonate electrically, or “ring,” to signals of this frequency, like a tuning fork responding to a musical note of proper pitch. This resonance is detected by the radar receiver. The amount of resonance appearing at the receiver output (the oscilloscope) is a function of the power transmitted, the tuning of the cavity, and the tuning and amplification of the receiver. Accordingly, the echo box provides a test of the overall efficiency of the radar system, eliminating atmospheric variables.
Industry:Weather
An ion counter in which the free airstream flows between polarized condenser plates that attract and capture ions of opposite sign. It is used for the measurement of the concentration and mobility of small ions in the atmosphere.
Industry:Weather
The boiling of a liquid; specifically, the formation within the liquid of bubbles of that liquid's vapor and the vigorous ascent of the bubbles to the liquid's surface, a process that usually begins at that liquid's nominal boiling point. Ebullition produces a much greater rate of escape of liquid molecules into the vapor phase than does evaporation, since the effective area for phase change is much greater in a boiling liquid than in a liquid evaporating from the same container, in that each bubble affords surface area for local evaporation.
Industry:Weather
