A series of Nansen-bottle water samples and associated temperature observations resulting from one release of a messenger.

The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.

A thermometer, invented by James Six in 1782, which simultaneously indicates the maximum and minimum temperatures attained during a given interval of time. A U-tube min/max thermometer

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.

Solar and terrestrial radiation directed upward (away From the earth's surface); outgoing radiation.

An instrument whose calibration can be determined by means of simple physical measurements on the instrument. Compare to secondary instrument.

A measure of the relative power, or of the relative values of two flux densities, especially of sound intensities and radar power densities. The decibel is derived from the less frequently used unit, the bel, named in honor of Alexander Graham Bell.

Overflowing by water of the normal confines of a stream or other body of water, or accumulation of water by drainage over areas which are not normally submerged.

A vent used with pressure sensors to reduce the effect of wind on the pressure inlet. It is normally mounted remotely and connected to the sensor using airtight tubing.

A system of estimating and reporting wind speed, originally based on the effect of various wind speeds on the amount of canvas that a full-rigged nineteenth century frigate could carry.

A special type of radar target, usually a comer reflector, tied beneath a free balloon and designed to be an efficient reflector of radio energy.

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

A thermometer consisting of a clock mechanism the speed of which is a function of temperature.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

General name for a type of instrument which measures the inclination of the wind to the horizontal plane. See bivane.

Solar and terrestrial radiation directed downwards (towards the earth's surface); incoming radiation.

The rate of decrease of pressure per unit distance at a fixed time.

Wind with a speed between 17 and 21 knots (19 and 24 mph); Beaufort scale number 5.

A radiosonde whose carrier wave is switched on and off in such a manner that the interval of time between the transmission of signals if a function of the magnitude of the meteorological elements being measured.

A device that combines several separate communications signals into one and outputs them on a single line.