An element that can control current without moving parts, heated filaments, or vacuum gaps.

Emission or transfer of energy in the form of electromagnetic waves or particles.

Name applied to a class of instruments which measure the liquid content of the atmosphere.

An instrument used to measure the amount of dew formed on a given surface.

An instrument used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

A component of a radiosonde consisting of a series of alternate electrically conducting and insulating strips. As these are scanned by a contact the radiosonde transmits temperature and humidity signals alternately. The contact may be a baroswitch as in t ...

The difference between the input quantity applied to a measuring instrument and the output quantity indicated by the instrument. The inaccuracy of an instrument is equal to the sum of its instrument error and its uncertainty.

The temperature at which a solid substance undergoes fusion, i.e. melts, changes from solid to liquid form. All substances have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is ...

A sounding balloon which, when operationally inflated, resembles an inverted teardrop.

That portion of the record of a microbarograph between any two (or a specified small number) of successive crossings of the average pressure level (in the same direction). Analogous to microseism.

Precipitation composed of white or translucent ice crystals, chiefly in complex branched hexagonal forms.

Same as rain gauge.

The unit of speed in the nautical system; one nautical mile per hour. It is equal to 1.1508 statute miles per hour or 0.5144 meters per second.

The lowest value of a measured quality at which a sensor responds. Compare to tracking.

Same as balloon cover.

The portion of the precipitation on the land which ultimately reaches the streams. especially the water from rain or melted snow that flows over the surface.

The amount of moisture which, if available, would be removed from a given land area by evapotranspiration. Expressed in units of water depth.

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

A general term for instruments designed to measure the amount of cloudiness.

A reversing thermometer which is encased in a strong glass outer shell that protects it against hydrostatic pressure. Compare to unprotected thermometer.