A unit of luminous intensity of a light source.

Same as photometer.

The length of fluid flow (gas or liquid) past a sensor required for the sensor to respond to 63.2% of a step change in speed. Expressed in feet or meters. For anemometers, this value is calculated from time constant times wind tunnel speed.

Same as evaporative power.

An instrument that automatically records pressure and temperature.

Radio Direction Finder.

A form of psychrometer with wet-bulb and dry-bulb thermometers mounted on opposite sides of a specialty designed graph of the psychrometric tables. It is so arranged that the intersections of two curves determined by the wet-bulb and dry-bulb readings -yi ...

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

The element directly responsive to the value of the measured variable.

An instrument for measuring snow hardness in terms of the resistance of snow to the pressure exerted by a disk attached to a spring-loaded rod, a gauge calibrated in pounds per square inch registers the amount of resistance. See Canadian hardness gauge.

A hydrometeor consisting of a visible aggregate of minute water and/or ice particles in the atmosphere above the earth's surface. Cloud differs from fog only in that the latter is, by definition, in contact with the earth's surface.

That portion of the atmosphere which is above the lower troposphere. Generally applied to levels above 850 mb.

Lacking a relationship to a time base or clock. In asynchronous communications, individual data characters are sent at an arbitrary rate.

A type of photoelectric photometer used to measure high-altitude winds on the assumption that stellar scintillation is caused by atmospheric inhomogeneities being carried along by wind near the tropopause level.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifteenth contact of the commutator, up to a number determined by the design of the commutator, and each fifth contact thereafter. This signal is t ...

The effect upon the measurement of rainfall caused by the presence of the rain gauge.

A small balloon, loaded with ballast and inflated so that it will explode at a predetermined altitude, which is attached to a larger balloon.

Determined by weighing a special type of wooden stick that has been exposed in the woods, its weight being proportional to its contained water.

The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve. Usually expressed as a percentage of full- scale range.

The array of indicating marks and figure in relation to which the position of an index is observed, i.e. a scale plate on a recorder.