Vacuum tube electrometer-
An electrometer that makes use of the amplifying properties of specially designed vacuum tubes. These instruments are more rugged than the electrostatic electrometer and possess the additional advantage of being easily converted into self-registering instruments.
Vane -
An instrument used to indicate or measure wind direction.
Variograph -
A recording variometer designed to study very small fluctuations of some quantity (the microbarograph is an example of a recording pressure variometer, a common form is an instrument designed to measure small changes in altitude by sensing small pressure changes.)
Variometer-
An instrument designed to study very small fluctuations of some quantity (the microbarograph is an example of a recording pressure variometer, a common form is an instrument designed to measure small changes in altitude by sensing small pressure changes.)
Velocity azimuth display wind profile-
Vertical profile of horizontal wind vectors derived from a scanning Doppler radar using a velocity–azimuth display algorithm.
Velocity rod -
Floating rod weighted at the base so that it travels in an almost vertical position; the immersed portion may be adjustable.
Ventilated psychrometer -
A hygrometer that is artificially aspirated; in this way proper readings can be obtained within about three minutes.
Venturi tube-
A tube designed to measure the rate of flow of fluids. It consists of a tube having a constriction or throat at its midsection. The difference between the pressure measured at the inlet and at the throat is a function of the fluid velocity. The instrument is frequently used in wind-tunnel work and as a speed indicator for aircraft.
Vertical anemometer-
(Also called vertical-axis anemomemeter.) General name for an instrument designed to measure the vertical component of the wind speed.
Vertical beam radar-
A radar employing a vertically pointing beam. "
Vertical current recorder-
General term for an instrument that records the vertical electric current in the atmosphere.
Vidicon camera-
A storage-type, electronically scanned photoconductive television camera tube that often has a response to radiation beyond the limits of the visible region; particularly used in early space applications, since no film was required.
Virtual impactor-
Instrument used to sample particles of a given size range according to their inertia. In the counterflow virtual impactor, a stream of air coming out of the instrument is used to reject particles with less than a specified inertia (size).
Visibility meter-
The general term for instruments used to make direct measurements of visual range in the atmosphere or of the physical characteristics of the atmosphere that determine the visual range.
Visibility recorder-
(Also called a visibility meter.) The general term for instruments used to make direct measurements of visual range in the atmosphere or of the physical characteristics of the atmosphere that determine the visual range.
Visible Infrared Spin Scan Radar Atmospheric Sounder-
An advanced version of the VISSR instrument that provided atmospheric sounding functions in addition to imaging functions.
Visible Infrared Spin Scan Radiometer -
The primary meteorological sensor providing imaging functions on the SMS and early GOES satellites.
Vortex thermometer -
A thermometer, used in aircraft, that automatically corrects for adiabatic and frictional temperatures rises by imparting a rotary motion to the air passing the thermal sensing element.
Vortex tube-
The closed surface or tube consisting of the vortex lines passing through every point of a given closed curve.
Voss polariscope-
A modification of the Savart polariscope in which a Wollaston prism is used as an analyzer. This instrument has a large colorless field and a high fringe-brightness level.
