A cup anemometer with its shaft mechanically coupled to a magneto.

The interval between the lower and upper measuring limits of an instrument, i.e. a thermometer with a range of -35 to 50

In aviation terminology, route or terminal weather conditions of sufficiently low visibility to require the operation of aircraft under instrument flight rules.

A rainbow of angular radius of about 50

The height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified as "thin" or "partial." The ceiling is termed unlimited when these conditions are not satisfied. ...

The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve. Usually expressed as a percentage of full- scale range.

A clay atmometer consisting of a hollow ceramic sphere through which evaporation occurs. Evaporation is measured by the loss of water from the reservoir which feeds the sphere.

A self-recording thermometer.

An atmospheric sounding instrument which is supported by a captive balloon and used to obtain temperature and humidity data from the ground level to a height of a few thousand feet. The data is telemetered to the ground through a wire cable.

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.

Any device or instrument for measuring salinity, especially one based on electrical conductivity methods.

A recording anemoclinometer.

The atmospheric pressure at mean sea level either directly measured by stations at sea level or empirically determined from the station pressure and temperature by stations not at sea level. Used as a common reference for analyses of surface pressure patt ...

Amount of solar radiation incident, per unit area and time, on a surface which is perpendicular to the radiation and is situated at the outer limit of the atmosphere, the earth being at its mean distance from the sun. It equals approximately 2.00 ly/ min ...

An instrument which measures the instantaneous rate at which rain is falling on a given surface. Also called a rate-of-rainfall gauge.

A thermometer which utilizes the thermal properties of gas. There are two forms of this instrument: (a) a type in which the gas is kept at constant volume, and pressure is the thermometric property, and (b) a type in which the gas is kept at constant pres ...

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

See hydrologic accounting.

Operation mode of a communication circuit in which each end can simultaneously transmit and receive.

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 ...