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 ...

The total of direct solar radiation and diffuse sky radiation received by a unit horizontal surface. Global radiation is measured by pyranometers.

A sounding balloon which, when operationally inflated, resembles an inverted teardrop.

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.

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.

A local variation of the wind vector or any of its components in a given direction.

Same as mercury barometer.

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

A type of electrical thermometer consisting of two thermocouples which are series-connected with a potentiometer and a constant-temperature bath. One couple, called the reference junction, is placed in a constant-temperature bath, while the other is used ...

A systematic observational error due to the characteristics of the observer. The uncertainty in a reading made by an observer may be acertained by a statistical analysis of his or her readings.

An instrument for measuring the extinction coefficient in water.

Programs or instructions which are stored in readonly memory.

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"

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 ...

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

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

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.

A general term for instruments which sample atmospheric suspensoids by impaction. Same as impactometer.

Small particle on which water vapor condenses.

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