Automated Weather Observing Station. A self-contained weather station designed to make aviation weather observations without operator involvement.

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

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 ...

A thermometer using transducing elements which deform with temperature. Examples are the bimetallic thermometer and the Bourdon tube type of thennometer.

Automated Local Evaluation in Real Time. Network of automatic rain gauges that transmit via VHF radio link when precipitation occurs. Some sites are also equipped with other sensors such as temperature, wind, pressure, river stage or tide level. More info ...

pattern barometer-Mercurial barometer with a fixed scale and cistern and which therefore requires only one adjustment before each reading.

Same as balloon cover.

Wind with a speed between 4 and 27 knots (4 and 31 mph); Beaufort scale numbers 2 through 6.

An inert gas. A colorless, monatomic element which is found to occur in dry air to the extent of only 0.000524 percent by volume. Helium is very light, having a molecular weight of only 4.003 and specific gravity referred to air of 0.138. Because helium i ...

The frequency of a carrier wave.

A measure of the relative power, or of the relative values of two flux densities, especially of sound intensities and radar power densities. The decibel is derived from the less frequently used unit, the bel, named in honor of Alexander Graham Bell.

A hygrometer using goldbeater's skin as the sensitive element. Variations of the physical dimensions of the skin caused by its hygroscopic character indicate relative humidity. (Note: Goldbeater's skin is the prepared outside membrane of the large intesti ...

The number of cycles per second between the limits of a frequency band.

Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale. fts construction permits dew point variations to be indicated approximately.

The pressure unit of the meter-ton-second system of physical units. equal to 10 millibars or 101 dynes per cm2.

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

A description or explanation of the manner in which the height of the ceiling is determined, i.e. aircraft ceiling, balloon ceiling. estimated ceiling, indefinite ceiling, measured ceiling, precipitation ceiling.

The downward flux of atmospheric radiation passing through a given level surface, usually taken as the earth's surface. This result of infrared (long-wave) absorption and reemission by the atmosphere is the principal factor in the greenhouse effect.

An ion counter of the aspiration condenser type, used for the measurement of the concentration and mobility of small ions in the atmosphere.

A wind blowing in the same direction as the heading of a moving object. thus assisting the object's intended progress. The opposite of a head wind.