Same as recording rain gauge.

A navigational aid used to facilitate the landing of an aircraft at an airport in instrument weather, i.e. low visibility.

The line-of-sight distance between two objects.

Of equal or constant pressure, with respect to either space or time.

The rate of decrease of pressure per unit distance at a fixed time.

Determination of the total amount of snow covering a watershed or a given region. Both depth and water content of the snow may be measured, and the results may be used to predict the amount of water that will be available after melting.

Solar radiation of selected wavelengths.

A unit of illuminance or illumination equal to one lumen per foot'. This is the illuminance provided by a light source of one candle at a distance of one foot.

A unit of mass numerically equal to the molecular weight of the substance. The gram-mote or gram-molecule is the mass in grams numerically equal to the molecular weight, i.e. a gram-mole of oxygen is 32 grams.

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.

Apparatus from which the nature and time of precipitation may be determined.

modulated radiosonde-A radiosonde which transmits the indications of the meteorological sensing elements in the form of pulses spaced in time. The meteorological data are evaluated from the intervals between the pulses. Also called timeinterval radiosonde ...

An instrument for taking photographs of an image of the sun in monochromatic light.

A reversing thermometer which is encased in a strong glass outer shell that protects it against hydrostatic pressure. Compare to unprotected thermometer.

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

A line drawn through points of equal humidity on given surface.

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

A small balloon whose ascent is followed by a theodolite in order to obtain data for the computation of winds aloft.