A pyrheliometer of the thermoelectric type. Radiation is allowed to fall on two concentric silver rings, the outer covered with magnesium oxide and the inner covered with lamp black. A system of thermocouples (thermopile) is used to measure the temperatur ...

Same as recording rain gauge.

Precipitation of very small, white opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm. The solid equivalent of drizzle.

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

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

An aneroid barometer with a scale graduated in altitude instead of pressure units.

A hygrometer in which the sensitive element is a strand or strands of human hair, the length of which is a function of the relative humidity of the air.

Difference between the instantaneous wind velocity at a point and the mean wind velocity taken over a given time interval. Also called fluctuation velocity.

A basic equation in night visual range theory, relating the illuminance of a point source of light to distance and the transmissivity of the atmosphere.

Value of soil moisture, expressed as a percentage of the mass of dry soil, below which a plant living in the soil dies by wilting.

A pressure-operated switching device used in a radiosonde. In operation, the expansion of an aneroid capsule causes an electrical contact to scan a radiosonde commutator composed of conductors separated by insulators.

An instrument used to indicate wind direction.

A fixed-length group of bits representing the large data element handled as a unit by a computer. Word length is determined by the capacity of the CPU registers.

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

Same as marine rainbow.

Temperature based on an absolute scale.

The change in a performance characteristic caused by a change in a specified operating condition from reference operating condition, all other conditions being held within the limits of reference operating conditions.

In meteorology, an area of low pressure; a low or trough.

A large body of air having similar horizontal temperature and moisture characteristics.

Winds which, over a small area, differ from those which would be appropriate to the general pressure distribution.