Wind with a speed between 4 and 27 knots (4 and 31 mph); Beaufort scale numbers 2 through 6.

A mercury barometer in which the lower mercury surface is larger in area than the upper surface. The basic construction of a cistern barometer is as follows: A glass tube one meter in length, sealed at one end is filled with mercury, and then inverted. Th ...

The inaccuracy that the manufacturer permits when the unit is calibrated in the factory.

Literally "not wet", containing no liquid.

See bimetallic thermometer.

Instrument for measuring the depth to which the soil is frozen.

Old snow that has become granular and compacted as a result of melting and refreezing.

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.

A hygrometer using goldbeater's skin as the sensitive element. Variations of the physical dimensions of the skin caused by its hygroscopic character indicate relative humidity. (Note: Goldbeater's skin is the prepared outside membrane of the large intesti ...

Strong winds concentrated within a narrow band in the atmosphere. The jet stream often "steers" surface features such as front and low pressure systems.

Fine dust or salt particles dispersed through a portion of the atmosphere; a type of lithometer. The particles are so small they cannot be felt or seen with the naked eye. Many haze formations are caused by the presence of an abundance of condensation nuc ...

A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

Radio Direction Finder.

Pertaining to measurements or devices in which the output varies continuously, i.e. voltage or rotation signals. Compare to digital.

General name for a type of instrument which measures the inclination of the wind to the horizontal plane. See bivane.

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

An instrument, located at the surface observing station, which is used to record the data presented by a radiosonde aloft.

Winds from the four cardinal points of the compass; that is, north, east, south, and west winds.

The height at which the maximum wind speed occurs, determined in a winds-aloft observation.

The cardinal points of the compass, i.e. north, south, east, west.