The range of operating conditions of a device within which operating influences are negligible. The range is usually narrow. Reference operating conditions are the conditions under which reference performance is stated and the base from which the values o ...

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 hydrostatic principle that pressure supplied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to the walls of the containing vessel.

A numbering system using a base number of 16 and including the ten decimal digits (0 to 9) along with six alpha digits (A to F). Thus. a digit is available to represent each of the possible values of a 4-bit binary digit.

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

An instrument for the measurement of the net flux of downward and upward total (solar and terrestrial) radiation through a horizontal surface.

The distance or length of flow of the air past a point during a given interval of time.

A thermometer used in aircraft which automatically corrects for adiabatic and frictional temperature rises by imparting a rotary motion to the air passing the thermal sensing element.

General name for an instrument designed to measure the vertical component of the wind speed. See anemoclinometer.

An instrument for determining the direction from which radio waves approach a receiver. It may consist of a manually operated direction indicator, or it may use a servo system to position the antenna automatically in the direction of the incident waves. T ...

An instrument for measuring the extinction coefficient in water.

Barometer in which pressure is determined by balancing air pressure against the weight of a column of mercury in an evacuated glass tube.

That temperature at which, in a specified latitude, the reading of a particular barometer requires no temperature or latitude correction.

Abbreviation for mean sea level.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

An evaluation of upper air temperature, pressure, and humidity from radio signals received from a balloon- borne radiosonde.

A small, moveable graduated scale adjacent and parallel to the main scale of an instrument. It provides a means for interpolating between the graduations of the main scale.

The maximum positive and negative deviation observed in testing a device under specified conditions and by a specified procedure. It is usually measured as an inaccuracy and expressed as accuracy, typically in terms of the measured variable, percent of sp ...

Programs or instructions which are stored in readonly memory.