Same as precipitation-evaporation ratio.

Erasable Programmable Read Only Memory. Programable read-only memory which can be erased, usually by ultraviolet light, and re-programmed.

A hygrometer which uses a transducing element whose electrical properties are a function of atmospheric water vapor content. The humidity strip and carbon-film hygrometer element are examples of such a transducer.

An instrument for measuring the extinction coefficient in water.

An apparatus, used in studying soil temperatures, for measuring the total supply of heat during a given period.

Any horizontal wind velocity tangent to the contour line of a constant pressure surface (or to the isobar of a geopotential surface) at the point in question.

The group of bits which a computer processes as a unit; often, 8 bits.

A mercury barometer of the fixed cistern type in which a moveable scale terminating in an ivory point is used to compensate for the variations in the height of the mercury in the cistern

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

Same as dew-point hygrometer.

A graphical device used for the determination of the speed of the geostrophic wind from the isobar or contour-line spacing on a synoptic chart.

The addition of one or more redundant bits to information to verify its accuracy.

A special form of the aspiration psychrometer. developed by Assmann, in which the thermometric elements are well shielded from radiation. Psychrometric measurements may be taken with the instrument in the presence of direct solar radiation.

The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.

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

A type of precipitation composed of unbranched crystals in the form of needles, columns, or plates. Usually has a very slight downward motion and may fall from a cloudless sky.

Abbreviation for precipitation-evaporation quotient.

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.

A thin metal disc partially evacuated of air used to measure atmospheric pressure by measuring its expansion and contraction.