See calorie.

An instrument, for the recording of two or more meteorological parameters, in which the ventilation is provided by a suction fan.

A line drawn through geographical points where a given seasonal biological event occurs on the same date.

A thermoelectric thermometer used for measuring air temperature. The name is derived from the fact that the reference thermocouple is placed in an insulated bottle.

An instrument used to determine atmospheric pressure or elevation by observing the boiling point of water or both liquids. The sensitivity of the hypsometer increases with decreasing pressure, making it more useful for high altitude work.

The atmospheric pressure at mean sea level either directly measured by stations at sea level or empirically determined from the station pressure and temperature by stations not at sea level. Used as a common reference for analyses of surface pressure patt ...

Same as geostrophic wind level.

Radio Direction Finder.

The correctable part of the inaccuracy of an instrument.

Radiation with wavelengths less than 4 microns.

The record of a barograph.

A device attached to a meteorological instrument to provide ventilation; usually a suction fan.

The sum of solar and terrestrial radiation.

The length of fluid flow (gas or liquid) past a sensor required for the sensor to respond to 63.2% of a step change in speed. Expressed in feet or meters. For anemometers, this value is calculated from time constant times wind tunnel speed.

An anemometer utilizing the principle that the pitch of the aeolian tones generated by air moving past an obstacle is a function of the speed of the air. Largely a curiosity and has been put to no practical application in modem meteorology.

A plastic molding component formed by the reaction of phenol and formaldehyde. It can be heavily reinforced or "filled" with glass fibers or other materials. Phenolics are known for their high impact strength, excellent wear characteristics, and dimension ...

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.

Rain gauge which registers precipitation that is too light to be registered by ordinary recording of the depth of water from precipitation. Same as ombrometer.

The source of illumination for an antenna reflector. Also called antenna feed.

A Sunshine recorder of the type in which the time scale is supplied by the motion of the sun. The instrument, which is pointed at the celestial pole, consists of a hemispherical mirror mounted externally on the optical axis of a camera. The lens of the ca ...