Same as water year.

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.

The most common of the principal rainbow phenomena, which appears as an arc of about 42

A pressure tube anemometer, consisting of a pitot tube mounted on the windward end of a wind vane and a suitable manometer to measure the developed pressure and calibrated in units of wind.

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 line drawn through points of equal humidity on given surface.

A self-recording psychrometer.

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.

Same as precipitation-evaporation ratio.

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.

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

Same as geostrophic wind level.

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

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 ...

The line-of-sight distance between two objects.

Temperature assumed by an unsaturated air parcel when brought adiabatically to a standard pressure (1,000 mb).

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

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