A basic equation in night visual range theory, relating the illuminance of a point source of light to distance and the transmissivity of the atmosphere.

A fixed-length group of bits representing the large data element handled as a unit by a computer. Word length is determined by the capacity of the CPU registers.

A unit of signaling speed representing the number of code elements sent per second; often, bits per second.

An instrument designed to measure quantities of heat. Sometimes used in meteorology to measure solar radiation.

An instrument for measuring the pressure of the atmosphere. The two principle types are aneroid and mercurial.

The group of bits which a computer processes as a unit; often, 8 bits.

Area of a computer or other device where various logic and control elements are interconnected. Often a printed circuit board into which other circuit boards plug at right angles.

A river gauge in which a weight suspended on a wire is lowered to the water surface from a bridge or other overhead structure to measure the distance from a point of known elevation to the water surface.

Same as luminous intensity.

An instrument which indicates the presence of dust particles in the atmosphere. Also spelled coniscope.

An absolute instrument developed by K. Angstrom for the measurement of direct solar radiation. The radiation receiver station consists of two identical manganin strips whose temperatures are measured by attached thermocouples. One of the strips is shaded, ...

A unit of pressure equal to 10' dyne per cm-' (101 barye), 1000 millibars. 29.53 inches of mercury.

The range through which the input may be varied without initiating a response. Usually expressed as a percentage of full-scale range.

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 hygrometer in which the sensitive element is a strand or strands of human hair, the length of which is a function of the relative humidity of the air.

See instrument error, observational error. random error, standard error, systematic error.

A medium-sized instrument shelter. It is a white louvered box with a flat double to of and is mounted four feet above the ground on a four-legged stand.

An instrument for determining the dust content of a sample of air. Also spelled conimeter.

A counterclockwise change in wind direction. Backing winds with height are indicative of cold air advection (CAA).

The writing component of a recording instrument.