A device used to hold liquid-in-glass maximum and minimum thermometers in the proper recording position inside an instrument shelter, and to permit them to be read and reset. See Townsend support.

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.

Abbreviation for the pressure, temperature, and humidity data obtained by a radiosonde observation.

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

A curve showing the variation of temperature with height in the free air. See lapse rate.

The array of indicating marks and figure in relation to which the position of an index is observed, i.e. a scale plate on a recorder.

Random Access Memory. The memory of a computer which can be read and written into at any location without passing through preceding locations.

An ion counter of the aspiration condenser type, used for the measurement of the concentration and mobility of small ions in the atmosphere.

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

A balloon designed to float at a constant pressure level. This may be accomplished by a pressure valve which controls the release of ballast so as to maintain flight above a selected pressure level until the supply of ballast is exhausted. See Moby Dick b ...

The addition of one or more redundant bits to information to verify its accuracy.

The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.

A common type of terrestrial scintillation; shimmering over a hot surface (such as a roadway) on a quiet, cloudless. summer day.

February 2nd. In American folklore, a day that is popularly supposed to provide the key to the weather for the remainder of the winter. Specifically, if the ground-hog upon emerging from its hole casts a shadow, it will return underground, thereby forebod ...

A conductor or system of conductors for radiating and/or receiving radio energy. Also called aerial.

A chronograph used to make a time-record of certain measured meteorological elements. The most common type, the triple register, records wind direction and speed, duration of sunshine, and amount of rainfall (sensed respectively by a contact anemometer, M ...

Winds from the four cardinal points of the compass; that is, north, east, south, and west winds.

A hydrometeor consisting of an aggregate of microscopic and more-or-less hygroscopic water droplets suspended in the atmosphere. It reduces visibility to a lesser extent than fog. The relative humidity of mist is often less than 95 percent.

An approximation to the complete equations describing atmospheric motion in which only the terms most important for the growth and decay of synoptic scale extratropical weather systems (i.e., the large areas of high and low pressure seen on weather maps) ...

A recording hair hygrometer.