A liquid-in-metal thermometer in which mercury is enclosed in a steel envelope. The change in internal pressure caused by the temperature variation is measured by a Bourdon tube which is connected to the mercury by a capillary tube. This instrument is hig ...

A measure of the intrinsic luminous intensity emitted by a source in a given direction. Luminance is a measure only of light. The comparable term for electromagnetic radiation in general is radiance.

Dihydrogen oxide, molecular formula H2O.

A strong wind characterized by a sudden onset, a duration on the order of minutes, and a rather sudden decrease in speed.

A continuous-recording barometer.

Any soft, gentle breeze.

General term for any device that measures precipitation: principally a rain gauge or snow gauge.

The correctable part of the inaccuracy of an instrument.

Quantitative Precipitation Forecast.

Lowest altitude in the atmosphere over a given location at which the air temperature is 0

Interational thermometric scale on which the freezing point of water equals 0

Contraction for radiosonde observation.

Downward-facing pyranometer used for measuring reflected solar radiation.

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,

Temperature assumed by an unsaturated air parcel when brought adiabatically to a standard pressure (1,000 mb).

A hygrometer which includes an arrangement for the time recording of atmospheric humidity.

Same as humidity strip.

Difference between the instantaneous wind velocity at a point and the mean wind velocity taken over a given time interval. Also called fluctuation velocity.

The actual time during which physical events take place.

An instrument resulting from the combination of a thermograph and a hygrograph and furnishing, on the same chart, simultaneous time recording of ambient temperature and humidity.