A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.

In physics, any process in which the flux density (or power, amplitude, intensity, illuminance, etc.) of a "parallel beam" of energy decreases with increasing distance from the source. Attenuation is always due to the action of the transmitting medium its ...

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

Same as water year.

An aviation weather forecast for a specific flight.

A recording anemometer.

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

An instrument which indicates the presence of precipitation. The ombroscope consists of a heated, water-sensitive surface which indicates by mechanical or electrical techniques the occurrence of precipitation.

A hygrometer which includes an arrangement for the time recording of atmospheric humidity.

A halo consisting of a faint white circle passing through the Sun and running parallel to the horizon for as much as 360

An absolute pyhrliometer, developed by C.G. Abbott, in which the radiation-sensing element is a blackened water-calorimeter.

The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve. Usually expressed as a percentage of full- scale range.

An instrument for measuring differences of electric potential.

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

Same as freezing point.

The distance or length of flow of the air past a point during a given interval of time.

Same as atmospheric pressure.

Water vapor content of the air. See absolute humidity, dew point, mixing ratio, relative humidity, specific humidity.

See hurricane beacon.

Same as instrument shelter.