A graduated scale placed in a position so that the stage of a stream may be read directly from it. Staff gauges may be placed on bridge piers or pilings, etc., or placed on specially constructed supports.

The elevation of the water surface in a stream as measured by a river gauge with reference to some arbitrarily selected zero datum.

A standard unit of atmospheric pressure, defined as the pressure exerted by a 760 mm column of mercury at standard gravity (980.665 cm/sec2 ) at O

The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.

One of several constant-pressure levels in the atmosphere for which a complete evaluation of data derived from upper air observations is required.

A vent used with pressure sensors to reduce the effect of wind on the pressure inlet. It is normally mounted remotely and connected to the sensor using airtight tubing.

The atmospheric pressure computed using station elevation as the reference datum level. Station pressure is usually the base value from which sea level pressure and altimeter setting are determined.

A unit of distance equal to 5280 feet. It is sometimes referred to as a land mile.

A type of instrument shelter. It is a wooden box painted white with double louvered sides and mounted on a stand four feet above the ground.

A cylinder installed in a body of water or an evaporation pan to hold a sensor, such as a float to measure water level or a hook gage. The stillwell is constructed so that there is free movement of water in and out of it, and it therefore provides a repre ...

Wind with a speed between 56 and 63 knots (64 and 72 mph); Beaufort scale number 11.

Same as river gauge.

Wind with a speed between 22 and 27 knots (25 and 31 mph); Beaufort scale number 6.

Wind with a speed between 41 and 47 knots (47 and 54 mph); Beaufort scale number 9.

Same as parhelion.

An instrument designed to record the duration of sunshine at a given location without regard to intensity. See Campbell- Stokes recorder, Jordan sunshine recorder, Marvin sunshine recorder, Pers sunshine recorder.

See constant-level balloon.

Liquid water at temperatures colder than freezing.

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

A power supply which achieves its output regulation by means of one or more active power handling devices which are alternately placed in the "off" or "on" states. It is more efficient than linear supplies which vary the conduction of power devices to ach ...