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

Any sudden and heavy rain, almost always of the shower type.

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

A thermometer using transducing elements which deform with temperature. Examples are the bimetallic thermometer and the Bourdon tube type of thennometer.

A hygrometer which uses a transducing element whose electrical properties are a function of atmospheric water vapor content. The humidity strip and carbon-film hygrometer element are examples of such a transducer.

The change in barometric pressure within a specified period of time (typically 3 hours for meteorological observations).

Same as fogbow.

The line-of-sight distance between two objects.

A radiosonde whose carrier wave is modulated by audio-frequency signals whose frequency is controlled by the sensing elements of the instrument.

An instrument for measuring the extinction coefficient in water.

Abbreviation for radio frequency.

The sum of solar and terrestrial radiation.

The value of the quantity measured, as indicated or otherwise provided by a measuring instrument.

Same as contact anemometer.

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.

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

Precipitation composed of balls or irregular lumps of ice with diameters between 5 and 50 mm.

Temperature assumed by an unsaturated air parcel when brought adiabatically to a standard pressure (1,000 mb).

The process whereby a position on the scale of an instrument is identified with the magnitude of the signal (or input force) actuating the instrument.

The total area drained by a river and its tributaries. Same as watershed.