An instrument, located at the surface observing station, which is used to record the data presented by a radiosonde aloft.

A very sensitive electrostatic electrometer for measuring small potential differences.

A device, similar to a phytometer, for measuring transpiration. It consists of a small vessel containing water and sealed so that the only escape of moisture is by transpiration from a leaf, twig, or small plant with its cut end inserted in the water.

See constant-level balloon.

A pyranometer developed by M. Robitzsch. Its design utilizes three bimetallic strips which are exposed horizontally at the center of a hemispherical glass bowl. The outer strips are white reflectors and the center strip is a blackened absorber. The bimeta ...

See radiosonde commutator.

An instrument used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

A thermometer, invented by James Six in 1782, which simultaneously indicates the maximum and minimum temperatures attained during a given interval of time. A U-tube min/max thermometer

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

Same as luminous intensity.

The amount of precipitation captured by a rain gauge.

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

The part of a measuring instrument which responds directly to changes in the environment.

A self-recording psychrometer.

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

See gain.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the mass of dry air. For many purposes, the mixing ratio may be approximated by the specific humidity.

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

A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.

See evaporation pan.