A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

An aneroid barograph designed to record atmospheric pressure variations of very small magnitude.

The atmospheric pressure at mean sea level either directly measured by stations at sea level or empirically determined from the station pressure and temperature by stations not at sea level. Used as a common reference for analyses of surface pressure patt ...

The record or trace made by a microbarograph.

Same as Aeolian.

See sea-water thermometer, reversing thermometer.

A device, similar to a potometer, for measuring transpiration, consisting of a vessel containing soil in which one or more plants are rooted and sealed so that water can escape only by transpiration from the plant.

Anemometer whicb measures wind speed by measuring the degree of cooling of a metal wire heated by an electric current. A type of cooling power anemometer.

A line drawn through points of equal humidity on given surface.

A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

Of or pertaining to rain.

A method of winds aloft observation accomplished by tracking a balloon-borne radar target or radiosonde with either radar or a radio theodolite.

Abbreviation for binary digit. The smallest unit of information, equal to one binary decision, i.e. 1/0, on/off, yes/no.

The record of an aneroid barograph.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the mass of dry air. For many purposes, the mixing ratio may be approximated by the specific humidity.

A forecast of weather elements of particular interest to aviation; including ceiling, visibility, upper winds, icing, turbulence, precipitation types, and storms.

An ion counter of the aspiration condenser type, used for the measurement of the concentration and mobility of small ions in the atmosphere.

See foehn.

A device for obtaining a continuous record of stage at a point on a stream. The most common recorders consist of a float-actuated pen which traces a record on a clock driven chart.

See evaporation pan.