A magnetometer of the electromagnetic type which is used to measure the horizontal intensity of the earth's magnetic field.

A radiosonde whose carrier wave is modulated by audio-frequency signals whose frequency is controlled by the sensing elements of the instrument.

General name for an instrument which measures the earth's magnetic field intensity.

A set of electrical conductors, often on a backplane, that carry data and power signals among the various components of a computer.

The play or loose motion in an instrument due to the clearance existing between mechanically contacting parts.

A liquid-in-glass thermometer which uses an organic substance such as alcohol as the thermometer liquid. This type of thermometer has a low freezing point and a high coefficient of expansion. It is less accurate, however, than a mercury thermometer.

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

The direction, with respect to true north, from which the wind is blowing. Distinguish from magnetic wind direction. In all standard upper-air and surface weather observations, it is true wind direction that is reported.

The ratio of the output of an instrument to the input value, i.e. a rain gauge with a sensitivity of 1 tip per 0.01"

A photoelectric spectrophotometer which is used in the determination of the ozone content of the atmosphere.

See constant-level balloon.

Random Access Memory. The memory of a computer which can be read and written into at any location without passing through preceding locations.

Solar radiation of selected wavelengths.

The size of the area comprising a watershed or river basin. Also called catchment area.

Electromagnetic radiation of very short wavelength. lying within the wavelength interval of 0.1 to 1.5 angstroms (between gamma rays and ultraviolet radiation). X-rays penetrate various thicknesses of all solids, and they act on photographic plates in the ...

A momentary decrease in the speed of the wind.

An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

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

A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

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 ...