The correctable part of the inaccuracy of an instrument.

A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.

In physics, any process in which the flux density (or power, amplitude, intensity, illuminance, etc.) of a "parallel beam" of energy decreases with increasing distance from the source. Attenuation is always due to the action of the transmitting medium its ...

A general name for instruments which detect the presence of (but do not necessarily measure) small electrical charges by electrostatic means. Compare to electrometer.

An instrument for measuring the pressure of the atmosphere. The two principle types are aneroid and mercurial.

A water-temperature thermometer provided with an insulated container around the bulb. It is lowered into the sea on a line until it has had time to reach the temperature of the surface water, then withdrawn and read. The insulated water surrounding the bu ...

A radar term for a single pulse of radio energy.

Operation mode of a communication circuit in which one end can only transmit and the other end can only receive.

The total area drained by a river and its tributaries. Same as river basin.

Temperature based on an absolute scale.

A self-recording psychrometer.

A large body of air having similar horizontal temperature and moisture characteristics.

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

An inert gas. A colorless, monatomic element which is found to occur in dry air to the extent of only 0.000524 percent by volume. Helium is very light, having a molecular weight of only 4.003 and specific gravity referred to air of 0.138. Because helium i ...

An instrument which measures the rate of evapotranspiration. It consists of a vegetation soil tank so designed that all water added to the tank and all water left after evapotranspiration can be measured.

A type of cooling-power anemometer based upon the principle that the time constant of a thermometer is a function of its ventilation.

The scientific study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surface. In terms of the hydrologic cycle, the ...

A thermopile used in some types of radiation instruments. See solarimeter.

In general, any self-recording instrument carried aloft by any means to obtain meteorological data.