A thermometer, invented by James Six in 1782, which simultaneously indicates the maximum and minimum temperatures attained during a given interval of time. A U-tube min/max thermometer

American Standard Code for Information Interchange. A standard code used to represent data using 8 bits (7 data bits and I parity bit) per character.

A pyrheliometer of the thermoelectric type. Radiation is allowed to fall on two concentric silver rings, the outer covered with magnesium oxide and the inner covered with lamp black. A system of thermocouples (thermopile) is used to measure the temperatur ...

The measurement and computation of wind speeds and directions at various levels above the surface of the earth. Methods include pilot balloon observations, rabals, rawin or rawinsonde observations, radar tracking, or acoustic sounding.

A type of pressure-plate anemometer in which the plate, restrained by a stiff spring, is held perpendicular to the wind. The wind-activated motion of the plate is measured electrically. The natural frequency of this system can be made high enough so that ...

Apparatus in which radar techniques are used to determine the range, elevation, and azimuth of a balloonborne target, to computer upper-air wind data. It is a type of rawin system.

Binary Coded Decimal. A coding system in which each decimal digit from 0 to 9 is represented by a 4-digit binary number.

The unit of acceleration in the centimeter-gram-second system of units, equal to one cm per sec2. Commonly used in gravimetry.

An aneroid barometer arranged so that the deflection of the aneroid capsule actuates a pen which graphs a record on a rotating drum. Sometimes called aneroidograph.

The direction, with respect to magnetic north, from which the wind is blowing. Distinguish from true wind direction.

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.

See radiosonde commutator.

An aneroid barometer with a scale graduated in altitude instead of pressure units.

A unit of signaling speed representing the number of code elements sent per second; often, bits per second.

A relatively small-scale, upward moving current of air.

A method of upper air observation consisting of an evaluation of the wind speed and direction, temperature, pressure, and humidity aloft by means of a balloon-borne radiosonde tracked by radar or a radio theodolite.

An aviation weather forecast for a specific flight.

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.

The length of air flow past a wind vane required for the vane to respond to 50 percent of a step change in wind direction. Expressed in feet or meters and calculated from delay time times wind tunnel speed.

An automatic, recording cloud height indicator.