A pyrheliometer of the bimetallic type used to measure the intensity of direct solar radiation.

An ice coating with a consistency intermediate between glaze and rime.

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

Any twelve-month period, usually selected to begin and end during a relative dry season. Used a basis for processing streamflow and other hydrologic data. The period from October 1 to September 30 is widely used in the U.S.

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator. By international agreement, the nautical mile is now defined as 1852 meters.

A current meter consisting of six conical cups, mounted around a vertical axis, which rotate and generate a signal with each rotation. Tail vanes and a heavy weight stabilize the instrument.

A common type of liquid-inglass thermometer, used, in meteorology, in psychrometers and as a maximum thermometer.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

A wind scale adapted by the U.S. Forest Service for use in the forested areas of the northern Rocky Mountains (NRM). It is an adaptation of the Beaufort wind scale. The difference between these two scales lies in the specification of the visual effects of ...

An instrument for measuring snow hardness in terms of the resistance of snow to the pressure exerted by a disk attached to a spring-loaded rod, a gauge calibrated in pounds per square inch registers the amount of resistance. See Canadian hardness gauge.

The degree of conformity of an indicated value to an accepted standard value, or ideal value. See accuracy rating, measured accuracy.

Same as water year.

General term for an instrument which records the vertical electric current in the atmosphere.

General term for an instrument used to make direct measurements of visual range or measurements of the physical characteristics of the atmosphere which determine the visible range.

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

Same as ceiling light.

An increase or amplification. There are two general usages of the term in radar meteorology: (a) antenna gain (or gain factor) is the ratio of the power transmitted along the beam axis to that of an isotropic radiator transmitting the same total power; an ...

A photometric unit of illuminance or illumination equal to one lumen per square centimeter.

A halo phenomenon consisting of a horizontal circle passing through the moon, corresponding to the parhelic circle through the sun. Produced by reflection of moonlight from ice crystals.