Pyrheliometer based on the comparison of the heating of two identical metal strips, one exposed to radiation, the other to a joule effect.

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

A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.

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.

A power supply which achieves its output regulation by means of one or more active power handling devices which are alternately placed in the "off" or "on" states. It is more efficient than linear supplies which vary the conduction of power devices to ach ...

See photometer.

The time required for an instrument to registe 63.2% of a step change in the variable being measured.

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.

An empirical curve relating stream discharge or stage at a point on a stream to discharge or stage at one or more upstream points and, possibly. to other parameters. Also called stage relation.

A hypothetical "body" whose surface absorbs no electromagnetic radiation of any wavelength. An idealization exactly opposite to that of the black body. In nature, no true white bodies are known. Moist white pigments exhibiting high reflectivity for visibl ...

Winds from the four cardinal points of the compass; that is, north, east, south, and west winds.

A rainbow of angular radius of about 50

A continuous-recording barometer.

Same as Aeolian.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the total mass of the system.

A hygrometer which includes an arrangement for the time recording of atmospheric humidity.

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

A precipitation gauge consisting of a receiver in the shape of a funnel which empties into a bucket mounted upon a weighing mechanism. The weight of the catch is recorded as inches of precipitation.

Air in motion relative to the surface of the earth. Almost exclusively used to denote the horizontal component.

As used by the U.S. Army Corps of Engineers, the departure (in