A cup anemometer with its shaft mechanically coupled to a magneto.

Electromagnetic radiation lying within the wavelength interval to which the human eye is sensitive, the spectral interval from approximately 0.4 to 0.7 microns (4000 to 7000 angstroms). Bounded on the short-wavelength end by ultraviolet radiation and on t ...

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

A sunshine recorder of the type in which the time scale is supplied by a chronograph. It consists of two bulbs, one of which is blackened, which communicate through a glass tube of small diameter. The tube is partially filled with mercury and contains two ...

Same as humidity strip.

The probability distribution of random errors, typically a normal distribution with a zero mean.

Any one of a family of circular arcs consisting of concentric colored bands, arranged from red on the inside to blue on the outside, which may be seen on a "sheet" of water drops (rain, fog, spray). The most common of the many possible is the primary rain ...

The water volume within a specified portion of a stream channel.

An absolute temperature scale with the ice point of pure water defined as 273.16 K. The size of the degree is the same as on the Celsius scale, and the zero point is absolute zero.

In Jeffreys' classification, a wind for which the pressure force exactly balances the viscous force, in which the vertical transfers of momentum predominate.

February 2nd. In American folklore, a day that is popularly supposed to provide the key to the weather for the remainder of the winter. Specifically, if the ground-hog upon emerging from its hole casts a shadow, it will return underground, thereby forebod ...

A basic equation in night visual range theory, relating the illuminance of a point source of light to distance and the transmissivity of the atmosphere.

A wave disturbance in airflow due to some barrier in the flow. i.e. a hill or mountain.

The component of the radiosonde which includes the modulating blocking oscillator and the radiofrequency carrier oscillator.

A instrument designed to study small fluctuations of some quantity. The microbarograph is an example of a recording pressure variometer.

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

The atmospheric pressure computed using station elevation as the reference datum level. Station pressure is usually the base value from which sea level pressure and altimeter setting are determined.

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

Precipitation composed of balls or irregular lumps of ice with diameters between 5 and 50 mm.

A defective maximum thermometer of the liquid-inglass type in which the mercury flows too freely through the constriction. Such a thermometer will indicate a maximum temperature that is too low.