Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

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

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

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.

Same as recording rain gauge.

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

The line-of-sight distance between two objects.

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

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

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.

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.

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

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

A recording siphon barometer.

A local variation in the wind direction or speed. This condition can present danger to aircraft, especially at landing, when a sudden shift from headwind to tailwind can cause a rapid loss of airspeed and lift.

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

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.

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

The processing of the form or mode of a signal so as to make it intelligible to, or compatible with, a given device.

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.