The upper surface of a column of liquid.

The temperature at which a solid substance undergoes fusion, i.e. melts, changes from solid to liquid form. All substances have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is ...

A thermometer which uses a transducing element whose element proper-ties are a function of its thermal state. Common meteorological examples of such thermometers are the resistance thermometer and the thermoelectric thermometer.

A refraction phenomenon similar to a parahelion, but occurring generally at a distance of 120

A halo consisting of a faint white circle passing through the Sun and running parallel to the horizon for as much as 360

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.

That part of snow melt that reaches stream channels as runoff.

The correctable part of the inaccuracy of an instrument.

A special type of radar target, usually a comer reflector, tied beneath a free balloon and designed to be an efficient reflector of radio energy.

The condition of the atmosphere when the amount of water vapor present is the maximum possible at the existing temperature.

A wooden enclosure about sixteen feet square and eight feet high with a precipitation gauge at its center. The function of the fence is to minimize eddies around the gauge and thus insure a catch that is representative of the actual rainfall or snowfall.

A common unit used in measurement of atmospheric pressure. Defined as that pressure exerted by a one-inch column of mercury at standard gravity and a temperature of 0'C.

A point (or line) on a scale used for reference or comparison purposes. In calibration of meteorological thermometers, for example, the fiducial points are 100

An instrument used to reveal but not necessarily measure the presence of an electrical quantity. It is used to display the output of a sensing element after suitable amplification and modification. Sometimes called display.

Same as marine rainbow.

Random Access Memory. The memory of a computer which can be read and written into at any location without passing through preceding locations.

Integrated Flood Observing and Warning System. National Weather Service flood warning program.

The state of the atmosphere, mainly with respect to its effects upon life and human activities. As distinguished from climate, weather consists of the short-term (minutes to months) variations of the atmosphere.

The interval between the lower and upper measuring limits of an instrument, i.e. a thermometer with a range of -35 to 50

The water volume within a specified portion of a stream channel.