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Ebert ion counterAn 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.
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ebullitionThe 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.
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echo boxA 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.
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echo contourA 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.
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