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

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

Wind with a speed between 34 and 40 knots (39 and 46 mph); Beaufort scale number 8.

Same as balloon cover.

An instrument for recording global solar radiation.

A unit of pressure used principally in oceanography. One decibar (10' dynes/cm2) equals 0.1 bar. In the ocean, hydrostatic pressure in decibars very nearly equals the corresponding depth in meters.

One of the radiation laws which states that the wavelength of maximum radiation intensity for a black body is inversely proportional to the absolute temperature of the radiating black body.

Downward scattered and reflected solar radiation, coming from the whole hemisphere with the exception of the solid angle of the sun's disc on a surface perpendicular to the axis of this cone.

The average temperature of the air as indicated by a properly exposed thermometer for a given time period, usually a day, a month, or a year.

A type of cooling-power anemometer based upon the principle that the time constant of a thermometer is a function of its ventilation.

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

A hygrometer which determines the amount of precipitable moisture in a given region of the atmosphere by measuring attenuation of radiant energy caused by the absorption bands of water vapor.

A magnetometer of the electromagnetic type which is used to measure the horizontal intensity of the earth's magnetic field.

See wind vane.

Same as freezing point.

Graduated fixed stake used in regions of abundant snowfall to facilitate the measurement of snow depth.

Same as water year.

A type of instrument shelter. It is a wooden box painted white with double louvered sides and mounted on a stand four feet above the ground.

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 metallic element of atomic weight 200.6 1, unique (for metals) in that it remains liquid under all but very extreme temperatures.