The ratios, to the mean wind speed, of the average magnitudes of the component fluctuations of the wind along three mutually perpendicular axes.

General term for an instrument used to make direct measurements of visual range or measurements of the physical characteristics of the atmosphere which determine the visible range.

The change in barometric pressure within a specified period of time (typically 3 hours for meteorological observations).

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifteenth contact of the commutator, up to a number determined by the design of the commutator, and each fifth contact thereafter. This signal is t ...

An instrument, located at the surface observing station, which is used to record the data presented by a radiosonde aloft.

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.

An anemometer which measures wind speed by means of the properties of wind-borne sound waves. It operates on the principle that the propagation velocity of a sound wave in a moving medium is equal to the velocity of sound with respect to the medium plus t ...

The total amount of water transferred to the atmosphere by evapotranspiration.

A system of physical units based upon the use of the meter, the metric ton (106 grams), and the second as elementary quantities of length, mass, and time, respectively.

Same as pitot tube.

Apparatus from which the nature and time of precipitation may be determined.

Precipitation composed of liquid water drops more than 0.5 mm in diameter, failing in relatively straight, but not necessarily vertical, paths. Compare to drizzle.

Name sometimes given to a transmissometer.

A temperature scale on which the freezing point of water equals 32

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 set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.

Root Mean Square. This notation is used frequently with error analysis. In that context, it is the square root of the arithmetic mean of the squares of the deviations of the individual calibration points from the theoretical or ideal response.

An atmometer which uses a filter paper disc as the evaporating element. The amount of water evaporated through the paper is read at the graduated tube reservoir.

Growth of a cloud or precipitation particle by the collision and union of a frozen particle with a super-cooled water drop.

A line drawn through geographical points having the same pluvial index.