An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine by the action of the sun's rays upon blueprint paper. A type of sunshine recorder.

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

The limiting values of ceiling, visibility, and wind, or runway visual range, established as safety minimum for aircraft landings and take-offs.

Very generally, any moving- stream of air. It has no particular technical connotation.

General name for an instrument which measures the evaporation rate of water into the atmosphere. See clay atmometer, evaporation pan, evapotranspirometer, Livingston sphere, Piche evaporimeter, radio atmometer.

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 small anemometer with flat vanes which indicates the number of linear feet or meters of air which have passed the instrument during its exposure.

See aneroid capsule.

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

Radio Direction Finder.

The indicating part of an instrument. For example, the hand of a watch or the meniscus of a mercury column.

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

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

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

Literally "not wet", containing no liquid.

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

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

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.

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

The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the "column" of air lying directly above the point in question.