A graphical representation of stage or discharge at a point on a stream as a function of time.

The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.

A wind vane used to obtain the horizontal and vertical components of the wind.

Any wind blowing down an incline. If warm, it is a foehn. If cold, it may be a fall wind or a gravity wind.

The process by which events in the real world are translated into machine-readable signals.

A sunshine recorder of the type in which the time scale is supplied by the motion of the sun. It consists of two opaque metal semi-cylinders mounted with their curved surfaces facing each other. Each of the semi-cylinders has a short narrow slit in its fl ...

A measure of the relative power, or of the relative values of two flux densities, especially of sound intensities and radar power densities. The decibel is derived from the less frequently used unit, the bel, named in honor of Alexander Graham Bell.

The ratio of the output of an instrument to the input value, i.e. a rain gauge with a sensitivity of 1 tip per 0.01"

pattern barometer-Mercurial barometer with a fixed scale and cistern and which therefore requires only one adjustment before each reading.

The difference between downward and upward (total) radiation; net flux of all radiation.

An instrument for measuring the difference of the solar radiation falling on both sides of a horizontal surface from the whole hemisphere.

An early and once universal name for the mercury barometer.

Wind with a speed between 7 and 10 knots (8 and 12 mph), Beaufort scale number 3.

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

A hygrometer which determines the amount of precipitable moisture in a given region of the atmosphere by measuring attenuation of radiant energy caused by the absorption bands of water vapor.

An aviation weather forecast for a specific flight.

A mercury barometer of the fixed cistern type in which a moveable scale terminating in an ivory point is used to compensate for the variations in the height of the mercury in the cistern

A photometric unit of illuminance or illumination equal to one lumen per square meter

An instrument whose calibration can be determined by means of simple physical measurements on the instrument. Compare to secondary instrument.

The stage, on a fixed river gauge, corresponding to the top of the lowest banks within the reach for which the gauge is used as an index. Compare to flood stage.