An instrument for determining the degree of polarization of light. See photopolarimeter.

Diffuse solar radiation which has the same intensity in all directions.

Same as recording rain gauge.

An instrument for studying, or examining substances in, polarized light. See Savant polariscope.

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 device which converts energy from one form into another, i.e. an ac generator transducer which converts the mechanical motion of anemometer cups into an electrical signal.

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.

A line drawn through geographical points where a given seasonal biological event occurs on the same date.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.

An element that can control current without moving parts, heated filaments, or vacuum gaps.

A set of rules or conventions used to standardize data transfer between devices.

Snow shower, particularly of a very light and brief nature.

Moisture contained in the soil above the water table, including water vapor which is present in the soil pores. In some cases this term refers strictly to the humidity contained in the root zone of plants.

As used by the U.S. Army Corps of Engineers, the departure (in

Atmospheric layer throughout which there is no change of temperature with height, i.e. a zero lapse rate.

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

Apparatus designed to measure the amount of precipitation falling in the form of snow. The device determines the weight of the snow or the volume of water after the snow melts.

Contraction for pilot balloon observation.

A recording siphon barometer.

Amount of water, expressed as a depth or as a mass, which would be obtained if all the water vapor in a specified column of the atmosphere were condensed and precipitated.