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

A method of winds aloft observation in which the elevation and azimuth angles of a theodolite are read while visually tracking a pilot balloon. Balloon height data is estimated from assumed balloon ascension rates.

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

Small particle on which water vapor condenses.

check chamber-A chamber use to check the sensing elements of radiosonde equipment.

Apparatus designed to measure the amount of precipitation falling in the form of snow. The device determines the weight of the snow or the volume of water after the snow melts.

Same as altimeter setting.

Of or pertaining to the air, atmosphere, or aviation. Also, same as antenna.

Same as evaporative power.

In general, solar radiation received at the earth's surface. Contracted from incoming solar radiation.

A systematic observational error due to the characteristics of the observer. The uncertainty in a reading made by an observer may be acertained by a statistical analysis of his or her readings.

in folklore, a name for fire.

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.

Reduction of visibility by strong winds blowing across dry ground with little or no vegetation. Visibilities of 1/8 mile or less over a widespread area are criteria for a Blowing Dust Advisory.

The ratio of the existing amount of water vapor in the air at a given temperature to the maximum amount that could exist at that temperature. Usually expressed in percent.

The boundary between the troposphere and stratosphere, usually characterized by an abrupt change in lapse rate. Its height varies from 10 to 20 km. Regions above the tropopause have greater atmospheric stability than regions below.

An instrument whose calibration can be determined by means of simple physical measurements on the instrument. Compare to secondary instrument.

A set of regulations set down by the U.S. Civil Aeronautics Board to govern the operational control of aircraft on instrument flight. The abbreviation of this term is seldom used to denote the rules themselves, but is in popular use to describe the weathe ...

Temperature based on an absolute scale.