General term for an instrument which records the vertical electric current in the atmosphere.

A combination cup anemometer and pressure-plate anemometer, consisting of an array of cups about a vertical axis of rotation, the free rotation of which is restricted by a suitable spring arrangement.

A thermometer which utilizes the thermal properties of gas. There are two forms of this instrument: (a) a type in which the gas is kept at constant volume, and pressure is the thermometric property, and (b) a type in which the gas is kept at constant pres ...

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

Turbulence encountered by aircraft when flying through air space devoid of clouds. Thermals and wind shear are the main causes.

An instrument used to indicate wind direction.

Wind with a speed between 7 and 10 knots (8 and 12 mph), Beaufort scale number 3.

Same as contact anemometer.

See evaporation pan.

The total of all deviations of a transducer's output from a specified straight line in a constant environment.

Same as mirror nephoscope.

An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

National Weather Service. Administered by the U.S. Department of Commerce.

A general term for instruments designed to measure the amount of cloudiness.

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

The ratio of the amount of electromagnetic radiation reflected by a body to the amount incipient upon it, commonly expressed as a percentage. The albedo is to be distinguished from the reflectivity, which refers to one specific wavelength.

A thermograph in which ventilation is provided by a suction fan.

A common type of terrestrial scintillation; shimmering over a hot surface (such as a roadway) on a quiet, cloudless. summer day.

Same as wind sock.

The standard deviation of a sufficiently large number of measurements of the same quantity by the same instrument or method. The non-correctable part of the inaccuracy of an instrument, it represents the limit of measurement precision. The uncertainty of ...