An instrument for measuring the pressure of gases and vapors. A mercury barometer is a type of manometer.

Abbreviation for mean sea level.

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

A nephoscope in which the motion of the cloud is observed by its reflection in a mirror.

A thermopile used in some types of radiation instruments. See solarimeter.

A small balloon whose ascent is followed by a theodolite in order to obtain data for the computation of winds aloft.

A mercury barometer arranged so that the position of the upper or lower meniscus may be measured photographically. In one design the image of the meniscus is formed on a rotating drum covered with sensitized paper so that a continuous record of pressure a ...

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

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

Wind with a speed between 56 and 63 knots (64 and 72 mph); Beaufort scale number 11.

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.

A motorlike device containing a rotor and a stator and capable of converting an angular position into an electrical signal, or an electrical signal into an angular position. When several synchros are correctly connected, all of the rotors will align thems ...

A barometer which measures atmospheric pressure using one or a series of aneroid capsules. Also called holosteric barometer.

Same as marine rainbow.

A hypothetical temperature characterized by a complete absence of heat and defined as 0 K, -273.15 C, or -459.67 F.

An instrument used for the determination of the electrical conductivity of the atmosphere.

Frequency Shift Keying. A form of frequency modulation of a data signal performed by a modem for transmission over dedicated wire or phone lines.

An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

Contraction for pilot balloon observation.

Cathode Ray Tube. A display element, consisting of a vacuum tube and screen, used with computers.