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

Abbreviation for precipitation-evaporation quotient.

In general, the transformation of data from a "raw" form to some useable form. In meteorology, this often refers to the conversion of the observed value of an element to the value which it would theoretically have at some selected or standard level. The m ...

See aneroid capsule.

variable audio-modulated radiosonde developed at the Bureau of Standards and used by the United States weather services.

The ratios, to the mean wind speed, of the average magnitudes of the component fluctuations of the wind along three mutually perpendicular axes.

Same as wave pole.

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

An instrument for measuring the relative speed of a fluid. It consists of a concentric pipe arrangement in which the inner pipe is open at one end and the outer pipe is perforated and closed at both ends. Each pipe is connected to a manometer. The unit is ...

An instrument which determines the black-body temperature of a substance by measuring its thermal radiation.

Same as water year.

A scale of yellows, greens, and blues for recording the color of sea water, as seen against the white background of a Secchi disk.

Same as atmometer.

A system in which radar techniques are used to determine the range, elevation, and azimuth of a radar target carried a!oft by a radiosonde, so that wind data may be obtained along with the other meteorological data.

An instrument for measuring radiant energy. It consists of an ether differential thermometer with blackened bulbs. One of the bulbs is exposed to the unknown radiation and the other to a black body source whose temperature can be varied. Equality of radia ...

A type of rain gauge shield consisting of freely hanging, evenly spaced slats arranged circularly around the gauge. The advantage of this shield is that the slats do not easily accumulate snow, permitting its use on unattended gauges. See rain gauge shiel ...

Binary Coded Decimal. A coding system in which each decimal digit from 0 to 9 is represented by a 4-digit binary number.

The difference between amounts of precipitation and runoff for a given storm. It is that portion of the precipitation that remains in the basin as soil moisture, surface storage, ground water, etc.

A thermometer consisting of a clock mechanism the speed of which is a function of temperature.

Literally "not wet", containing no liquid.