A sounding balloon which, when operationally inflated, resembles an inverted teardrop.

A pointed device which indicates the amount of resistance encountered when it is forced into a material such as snow or soil. See ram penetrometer.

Contraction for radiosonde observation.

The distance or length of flow of the air past a point during a given interval of time.

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 thermometer used in aircraft which automatically corrects for adiabatic and frictional temperature rises by imparting a rotary motion to the air passing the thermal sensing element.

An instrument for the measurement of the net flux of downward and upward total (solar and terrestrial) radiation through a horizontal surface.

A hydrostatic principle that pressure supplied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to the walls of the containing vessel.

General name for an instrument designed to measure the vertical component of the wind speed. See anemoclinometer.

A local variation of the wind vector or any of its components in a given direction.

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

See approximate absolute temperature scale, Celsius temperature scale, centigrade temperature scale, Fahrenheit temperature scale, Kelvin temperature scale, Rankine temperature scale, Reaumur temperature scale,

The maximum positive and negative deviation observed in testing a device under specified conditions and by a specified procedure. It is usually measured as an inaccuracy and expressed as accuracy, typically in terms of the measured variable, percent of sp ...

A photometric unit of illuminance or illumination equal to one lumen per square meter

A cylinder installed in a body of water or an evaporation pan to hold a sensor, such as a float to measure water level or a hook gage. The stillwell is constructed so that there is free movement of water in and out of it, and it therefore provides a repre ...

A rainbow formed by light rays which have been reflected from an extended water surface. Not to be confused with a reflected rainbow whose image may be seen in a still body of water. The center of a reflection rainbow is at the same elevation as the sun b ...

An evaluation of upper air temperature, pressure, and humidity from radio signals received from a balloon- borne radiosonde.

A device which automatically records the water equivalent of snow on a given surface as a function of time. A small sample of a radioactive salt is placed in the ground in a shielded collimator which directs a beam of radioactive particles upwards. A Geig ...

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

A small, moveable graduated scale adjacent and parallel to the main scale of an instrument. It provides a means for interpolating between the graduations of the main scale.