A device used to switch electrical current at a selectable setpoint temperature.

An instrument for measuring the difference between incoming and outgoing terrestrial radiation.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

Based upon damage patterns, classifies twisters into six categories of wind speed (F0 thru F5), ranging from 40 to 318 mph estimated wind speed.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifth contact of the commutator up to a number determined by the design of the commutator. It then signals every contact except the fifth, which is ...

An instrument whose calibration is determined by comparison with an absolute instrument.

A colorless and odorless gaseous element. The lightest and apparently the most abundant chemical element in the universe. However, it is found only in trace quantities in the observable portion of our atmosphere, only about 0.00005 percent by volume of dr ...

Frequency Shift Keying. A form of frequency modulation of a data signal performed by a modem for transmission over dedicated wire or phone lines.

A temperature scale with the ice point at 273 degrees and boiling point of water at 373 degrees. It is intended to approximate the Kelvin temperature scale with sufficient accuracy for many sciences, notably meteorology.

Same as rain gauge.

The correction applied to an instrument to account for the effect of temperature upon its response characteristics.

Same as instrument shelter.

The record of a barograph.

Fine dust or salt particles dispersed through a portion of the atmosphere; a type of lithometer. The particles are so small they cannot be felt or seen with the naked eye. Many haze formations are caused by the presence of an abundance of condensation nuc ...

The closeness of agreement among measurements of the same value of the same quantity where the individual measurements are made under different defined conditions, i.e. by different methods or with different measuring instruments.

A type of disk hardness-gauge, especially useful in relatively soft snow. See disk hardness gauge.

A hygrometer in which the sensitive element is a strand or strands of human hair, the length of which is a function of the relative humidity of the air.

A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

Same as balloon cover.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.