A device that combines several separate communications signals into one and outputs them on a single line.

The difference between the air temperature and the dew-point. Also called dew-point deficit, dew-point depression.

A rainbow seen in the spray of the ocean. It is optically the same phenomenon as the ordinary rainbow.

The temperature at which an object gives out as much radiation as it receives from its surroundings.

An instrument which automatically records the voltage applied to it, as a function of time.

Instrument for measuring the depth of water from precipitation that is assumed to be distributed over a horizontal, impervious surface and not subject to evaporation.

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

An instrument which automatically determines the size distribution of raindrops.

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

The temperature at which all three phases of a substance can exist in equilibrium. This temperature occurs at only one pressure. The triple-point of water is 273.16 K and is the basis of the Kelvin scale.

The component of the radiosonde which includes the modulating blocking oscillator and the radiofrequency carrier oscillator.

A small pointer extending downward from the top of the cistern of a Fortin barometer. The level of the mercury in the cistern is adjusted so that it just comes in contact with the end of the pointer, thus setting the zero of the barometric scale.

A box-like structure designed to protect certain meteorological instruments from exposure to direct sunlight, precipitation, and condensation, while at the same time providing adequate ventilation. Instrument shelters are painted white, have louvered side ...

A wind scale adapted by the U.S. Forest Service for use in the forested areas of the northern Rocky Mountains (NRM). It is an adaptation of the Beaufort wind scale. The difference between these two scales lies in the specification of the visual effects of ...

A calorimetric radiation instrument of historic interest used for the measurement of outgoing heat radiation from the earth during an interval of time. The time integration is performed by allowing the radiation to fall on an uninsulated vessel containing ...

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 balloon used to carry a radiosonde aloft, considerably larger than pilot balloons or ceiling balloons.

The maximum rate at which precipitation can pass through the surface into the soil, for a given soil in a given condition.

See ceilometer.

Temperarure at which a liquid solidifies under any given set of conditions. It may or may not be the same as the melting point or the more rigidly defined true freezing point or (for water) ice point.