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 inaccuracy that the manufacturer permits when the unit is calibrated in the factory.

Instrument for measuring the depth to which the soil is frozen.

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

Pertaining to measurements or devices in which the output varies continuously, i.e. voltage or rotation signals. Compare to digital.

General name for a type of instrument which measures the inclination of the wind to the horizontal plane. See bivane.

A device for obtaining a continuous record of stage at a point on a stream. The most common recorders consist of a float-actuated pen which traces a record on a clock driven chart.

Abbreviation for binary digit. The smallest unit of information, equal to one binary decision, i.e. 1/0, on/off, yes/no.

A surface weather observation, made at periodic times, of sky cover, state of the sky, cloud height, atmospheric pressure reduced to sea level, temperature, dew point, wind speed and direction. amount of precipitation, hydrometeors and lithometeors. and s ...

The height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified as "thin" or "partial." The ceiling is termed unlimited when these conditions are not satisfied. ...

The direction from which the wind is blowing, measured in points of the compass or in azimuth degrees.

A sunshine recorder of the type in which the time scale is supplied by a chronograph. It consists of two bulbs, one of which is blackened, which communicate through a glass tube of small diameter. The tube is partially filled with mercury and contains two ...

An ion counter of the aspiration condenser type, used for the measurement of the concentration and mobility of small ions in the atmosphere.

A clockwise change in wind direction. Veering winds with height are indicative of warm air advection (WAA).

In the direction from which the wind is blowing.

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

A description or explanation of the manner in which the height of the ceiling is determined, i.e. aircraft ceiling, balloon ceiling. estimated ceiling, indefinite ceiling, measured ceiling, precipitation ceiling.

An instrument for recording ocean waves. Most recorders are designed for recording wind waves, that is waves of periods up to about 25 seconds, but some are designed to record waves of longer periods such as tsunamis or tides.

A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.