A liquid-in-glass thermometer which uses an organic substance such as alcohol as the thermometer liquid. This type of thermometer has a low freezing point and a high coefficient of expansion. It is less accurate, however, than a mercury thermometer.

The direction toward which the wind is blowing; with the wind.

A clock-driven instrument mounting which automatically and continuously points in the direction of the sun. It is used with a pyrheliometera,hen continuous direct solar radiation measurements are required.

The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.

The envelope of air surrounding the earth and bound to it more or less permanently by virtue of the earth's gravitational attraction. The system whose chemical Properties. dynamic motions, and physical processes constitute the subject matter of meteorolog ...

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,

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

Abbreviation for radio frequency.

Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

A radar term for a single pulse of radio energy.

A scale of yellows, greens, and blues for recording the color of sea water, as seen against the white background of a Secchi disk.

That horizontal wind velocity at which the Coriolis acceleration exactly balances the horizontal pressure force. It is directed along contour lines or isobars.

A device for measuring the height of tide. It may be simply a graduated staff in a sheltered location where visual observations can be made, or it may consist of an elaborate recording instrument (sometimes called a marigraph) making a continuous graphic ...

The stage on a fixed river gauge at which it is necessary to begin issuing warnings or river forecasts if adequate precautionary measures are to be taken before flood stage is reached.

An instrument for measuring radiant energy. See actinometer, Dines radiometer, photometer, Tulipian radiometer.

Water vapor content of the air. See absolute humidity, dew point, mixing ratio, relative humidity, specific humidity.

An instrument which indicates the presence of dust particles in the atmosphere. Also spelled coniscope.

A type of atmometer. It is a pan used in the measurement of the evaporation of water into the atmosphere. The NWS Class A pan is a cylindrical container 48 inches in diameter and 10 inches deep.

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.

A type of recording siphon barometer. The mechanically magnified motion of a float resting on the lower mercury surface is used to record atmospheric pressure on a rotating drum.