Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

A diagram showing the intensity of the radiation field in all directions from a transmitting radio or radar antenna at a given distance from the antenna.

A transducer which converts electromagnetic radiation in the infrared, visible, and ultraviolet regions into electrical quantities such as voltage, current, or resistance. Also called photo cell.

A halo consisting of a faint white circle passing through the Sun and running parallel to the horizon for as much as 360

Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale. fts construction permits dew point variations to be indicated approximately.

A record obtained from a meteorograph. A chart in which meteorological variables are plotted against time.

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 chronograph used to make a time-record of certain measured meteorological elements. The most common type, the triple register, records wind direction and speed, duration of sunshine, and amount of rainfall (sensed respectively by a contact anemometer, M ...

An instrument which automatically records the measurement of two or more meteorological elements.

A hygrometer in which the rotation of the hygrometric element is a function of humidity.

Same as Aeolian.

An instrument designed to record the duration of sunshine at a given location without regard to intensity. See Campbell- Stokes recorder, Jordan sunshine recorder, Marvin sunshine recorder, Pers sunshine recorder.

A hypothetical body which absorbs some constant fraction, between zero and one, of all electromagnetic radiation incident upon it, which fraction is the absorptivity and is independent of wavelength. Compare to black body, white body.

A set of rules or conventions used to standardize data transfer between devices.

An instrument for measuring the extinction coefficient in water.

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

An instrument for determining the degree of polarization of light. See photopolarimeter.

A device used on certain types of instruments to prevent unwanted radiation from affecting the measurement of a quantity. Also called solar radiation shield.

A subtle, diumal component of the wind velocity leading to a diumal shift of the wind or turning of the wind with the sun, produced bv the east-to-west progression of daytime surface heating.

A general term for instruments designed to measure the speed or force of the wind.