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 ...

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

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

Instrument for measuring the mean intensity of glo global solar radiation (direct and diffuse) near the earth's surface in a specified time interval.

American Standard Code for Information Interchange. A standard code used to represent data using 8 bits (7 data bits and I parity bit) per character.

A device used on certain types of instruments to prevent unwanted radiation from affecting the measurement of a quantity. Also called solar radiation shield.

Same as dew-point hygrometer.

Name given to the unit of pressure in the International System of Units (SI). Equal to 1 newton/meter2 or 0.01 millibar.

Dihydrogen oxide, molecular formula H2O.

A transducer for converting thermal energy directly into electrical energy. It is composed of pairs of thermocouples which are connected either in series or in parallel. Thermopiles are used in thermoelectric radiation instruments when the output of a sin ...

A hypothetical "body" whose surface absorbs no electromagnetic radiation of any wavelength. An idealization exactly opposite to that of the black body. In nature, no true white bodies are known. Moist white pigments exhibiting high reflectivity for visibl ...

Pertaining to measurements or devices in which the output vanes in discrete steps, i.e. on-off or pulse signals. Compare to analog.

An air-launched balloon designed to be released in the eye of a tropical cyclone, float within the eye at predetermined levels, and transmit radio signals for RDF positioning.

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

Pyrheliometer based on the comparison of the heating of two identical metal strips, one exposed to radiation, the other to a joule effect.

A method of winds aloft observation essentially the same as a pilot balloon observation except the height data is derived from the radiosonde observation rather than from assumed ascension rates.

In a system of moist air, the ratio of the mass of water vapor to the total volume of the system. Usually expressed as grams per cubic meter (g/m3).

In nautical terminology, a contraction for "weather glass" (a mercury barometer).

A cylinder installed in a body of water or an evaporation pan to hold a sensor, such as a float to measure water level or a hook gage. The stillwell is constructed so that there is free movement of water in and out of it, and it therefore provides a repre ...

A liquid-in-metal thermometer in which mercury is enclosed in a steel envelope. The change in internal pressure caused by the temperature variation is measured by a Bourdon tube which is connected to the mercury by a capillary tube. This instrument is hig ...