Water-flow pyrheliometer -
An absolute pyrheliometer, developed by C. G. Abbot, in which the radiation-sensing element is a blackened water-calorimeter.
It consists of a cylinder, blackened on the interior, and surrounded by a special chamber through which water flows at a constant rate. The temperatures of the incoming and outgoing water,
which are monitored continuously by thermometers, are used to compute the intensity of the radiation. This instrument was built by the Smithsonian Institution but was never widely used as a standard instrument. The function of the instrument as an absolute reference is currently fulfilled by the absolute cavity radiometer.
Water-level recorder -
A device used for recording water levels in rivers, lakes, or wells, with respect to time.
Water-stage recorder -
A device for obtaining a continuous record of stage at a point on a stream.
Water thermometer-
A thermometer designed for use in measuring the temperature of seawater.
Wave recorder -
An instrument for recording ocean waves. Most wave recorders are designed for recording wind waves or swell, that is, waves of periods up to about 25 seconds, but some are designed to record waves of longer periods such as tsunamis or tides. See tide gauge, wave pole.
Weather gauge-
Same as barometer, an instrument for measuring atmospheric pressure.
Weather glass -
An old nautical term for mercury barometer, a glass manometer, employing mercury in its vertical column, that is used to measure atmospheric pressure.
Weather radar-
Generally, any radar that is suitable or can be used for the detection of precipitation or clouds.
Weather station-
A location where meteorological observations such as surface, upper air, and climatological observations are taken. (In a general sense, the term also includes service offices that prepare weather maps and charts, issue forecasts and warnings, issue weather briefings to pilots, and prepare and disseminate climatological information.)
Weather facsimile-
A communications service provided by the GOES, GMS, and Meteosat environmental satellites. (It involves acquisition and processing of environmental satellite data on the ground and retransmission of these data at VHF frequencies back through the geostationary spacecraft to low- cost ground readout sites.)
Weger aspirator -
An instrument of the aspiration condenser type that measures the concentration and mobility of small ions.
Weighing rain_gauge -
A recording rain gauge in which the weight of water collected is measured as a function of time and converted to rainfall depth.
Weight barograph -
A recording mercury barometer that measures atmospheric pressure by weighing the mercury in the column or the cistern.
Weight barometer -
A mercury barometer that measures atmospheric pressure by weighing the mercury in the column or the cistern.
Whirling psychrometer -
(Also called sling psychometer.) A psychrometer in which the wet- and dry-bulb thermometers are mounted upon a frame connected to a handle at one end by means of a bearing or length of chain.
Wideband radar -
A radar system of extremely wide bandwidth and high range resolution, usually implemented by the direct radiation of a very short (-1 ns) video pulse rather than the transmission of a short burst of a carrier wave.
Wilson cloud chamber-
A device that renders visible the paths of high energy subatomic particles.
Wind profiler-
A radar that is used to measure vertical profiles of the wind. In general the term is applied to Doppler radars operating in the VHF–UHF band (30 MHz– 3 GHz) that determine the wind by measuring the line-of-sight Doppler shift of scattered signals (Bragg scattering) from refractive index fluctuations caused by turbulence (see clear-air echo).
Wind sock -
A tapered fabric sleeve, shaped like a truncated cone and pivoted at its larger end on a vertical standard, for the purpose of indicating wind direction.
Wind turbine -
A device for converting wind energy into mechanical (windmill) or electrical energy.
Wind vane -
An instrument used to indicate or measure wind direction.
Windbreak -
Any device designed to obstruct wind flow and intended for protection against any ill effects of wind. Installations of this type include agricultural shelterbelts, snow fences, and rain-gauge wind shields.
Wire-weight gauge-
A river gauge in which a weight suspended on a wire is lowered to the water surface from a bridge or other overhead structure to measure the distance from a point of known elevation on the bridge to the water surface.
Wiresonde -
An atmospheric sounding instrument that is supported by a captive balloon and used to obtain temperature and humidity data from the ground level to a height of about 1 kilometer.
Weather Surveillance Radar–1988 Doppler -
( WSR - 88 D) The weather radar, sometimes called NEXRAD, that became the operational network radar for the U.S. National Weather Service, U.S. Air Force, and Federal Aviation Administration during the early and middle 1990s. It is a general-purpose weather radar with a wavelength of 10.5 cm, a peak power of 750 kW, selectable pulse duration of 1.57 or 4.0 ms, and selectable pulse repetition frequency from 318 to 1304 Hz. A coherent Doppler radar, it employs a center-fed parabolic antenna with a diameter of 8.5 m, producing a beamwidth of 0.95°.
Received signals are analyzed using the method of pulse-pair processing to give as fundamental data the reflectivity factor, mean Doppler velocity, and Doppler spread as functions of time and location relative to the radar. The maximum unambiguous range is ordinarily 460 km for reflectivity and 115 km for Doppler information. Many kinds of computer algorithms are employed for identifying features such as vortices, downbursts, and fronts.
