Name sometimes given to a transmissometer.

The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.

A recording anemometer.

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

Any quantity, such as force velocity, or acceleration, which has both magnitude and direction at each point in space, as opposed to scalar which has magnitude only. Such a quantity may be represented geometrically by an arrow of length proportional to its ...

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

A reflecting type telescope with a 45

A thin metal disc partially evacuated of air used to measure atmospheric pressure by measuring its expansion and contraction.

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

Solar and terrestrial radiation directed upward (away From the earth's surface); outgoing radiation.

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

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

A device for measuring the frequency of occurrence of atmospherics whose intensity is greater than a predetermined level.

A decrease in the central pressure of a pressure system. Usually applied to a low rather than to a high.

An instrument developed by K. Angstrom for measuring the effective terrestrial radiation. It consists of four manganin strips, of which two are blackened and two are polished. The blackened strips are allowed to radiate to the atmosphere while the polishe ...

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

An approximation to the complete equations describing atmospheric motion in which only the terms most important for the growth and decay of synoptic scale extratropical weather systems (i.e., the large areas of high and low pressure seen on weather maps) ...

Same as contact anemometer.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

A very sensitive electrostatic electrometer for measuring small potential differences.