A component of a radiosonde consisting of a series of alternate electrically conducting and insulating strips. As these are scanned by a contact the radiosonde transmits temperature and humidity signals alternately. The contact may be a baroswitch as in t ...

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.

An instrument which automatically determines the size distribution of raindrops.

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

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.

See sea-water thermometer, reversing thermometer.

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.

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.

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 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 ...

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

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

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 ...

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

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

The smallest change in the environment that causes detectable change in the indication of an instrument. Compare to sensitivity.

Precipitation composed of liquid water drops more than 0.5 mm in diameter, failing in relatively straight, but not necessarily vertical, paths. Compare to drizzle.

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