The value of atmospheric pressure to which the scale of a pressure altimeter is set so as to indicate airport elevation. The altimeter setting is included as part of an aviation weather observation.

A unit of pressure equal to 10' dyne per cm-' (101 barye), 1000 millibars. 29.53 inches of mercury.

An instrument which automatically determines the size distribution of raindrops.

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

In general. the severe wind of an intense tropical cyclone (hurricane or typhoon). The term has no further technical connotation, but, unfortunately, is easily conftlsed with the strictly defined hurricane-force wind,

The process by which one object becomes adhered to another by the binding action of ice.

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.

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.

Reduction of visibility by strong winds blowing across dry ground with little or no vegetation. Visibilities of 1/8 mile or less over a widespread area are criteria for a Blowing Dust Advisory.

The quantity to be measured (or modulated, or detected, or operated upon) which is received by an instrument. Thus, for a thermometer. temperature is the input quantity.

A device, similar to a phytometer, for measuring transpiration. It consists of a small vessel containing water and sealed so that the only escape of moisture is by transpiration from a leaf, twig, or small plant with its cut end inserted in the water.

The range of operating conditions of a device within which operating influences are negligible. The range is usually narrow. Reference operating conditions are the conditions under which reference performance is stated and the base from which the values o ...

A direct-vision nephoscope which is constructed in the following manner: a comb consisting of a crosspiece containing equispaced vertical rods is attached to one end of a column eight to ten feet long and is supported on a mounting that is free to rotate ...

A set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.

The number of cycles per second between the limits of a frequency band.

Same as rain-intensity gauge.

A mercury-in-glass thermometer which records the temperature upon being inverted and retains its reading until being returned to the first position.

An instrument for measuring the pressure of gases and vapors. A mercury barometer is a type of manometer.

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

A polarimeter utilizing a Wollaston prism as a polarizer and a Nicol prism as an analyzer.