An instrument for determining the direction of cloud motion. There are two basic designs of nephoscope, the directvision nephoscope and the mirror nephoscope.

Defect in the action of an aneroid barometer resulting in a sluggish adjustment of the index toward the correct reading when the barometer is subjected to a large and rapid change in pressure.

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

Same as fogbow.

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

NEXt Generation RADar. A NWS network of about 140 Doppler radars operating nationwide.

The upper surface of a column of liquid.

A cup anemometer with its shaft mechanically coupled to a magneto.

The interval between the lower and upper measuring limits of an instrument, i.e. a thermometer with a range of -35 to 50

Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays, between 0.02 and 0.4 micron (200 and 4000 angstrom).

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

The attenuation of light.

A thermometer with a muslin-covered bulb which is moistened. used to measure wet-bulb temperature.

The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

The gravity flow of water within soil.

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

See radar theodolite, radio direction-finder.

Nested Grid Model generated every 12 hours by NCEP.

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