A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.

An aneroid barograph designed to record atmospheric pressure variations of very small magnitude.

The group of bits which a computer processes as a unit; often, 8 bits.

Very generally, any moving- stream of air. It has no particular technical connotation.

A radar which is used to obtain the azimuth elevation, and slant range of an airborne target.

A navigational aid used to facilitate the landing of an aircraft at an airport in instrument weather, i.e. low visibility.

A mercury barometer arranged so that the position of the upper or lower meniscus may be measured photographically. In one design the image of the meniscus is formed on a rotating drum covered with sensitized paper so that a continuous record of pressure a ...

An instrument for determining the direction from which radio waves approach a receiver. It may consist of a manually operated direction indicator, or it may use a servo system to position the antenna automatically in the direction of the incident waves. T ...

Apparatus designed to measure and record the size distribution of raindrops as they occur in the atmosphere.

The time required for an instrument to register a designated percentage (frequently 90%) of a step change in the variable being measured.

The amount of sky covered or concealed by clouds or obscuring phenomena. It is reported in tenths, so that 0.0 indicates a clear sky and 1.0 (or 10/10) indicates a completely covered sky. The following classifications are used in aviation weather observat ...

The lowest value of a measured quality at which a sensor meets its accuracy specification.

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

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.

A protocol similar to RS232 which makes use of differential transmission to provide high speed data transmission over significantly longer distances.

Lacking a relationship to a time base or clock. In asynchronous communications, individual data characters are sent at an arbitrary rate.

That part of snow melt that reaches stream channels as runoff.

That part of an audio-modulated radiosonde consisting of the baroswitch, the sensing elements, the reference elements, and the relay.

Turbulence encountered by aircraft when flying through air space devoid of clouds. Thermals and wind shear are the main causes.

A device for measuring sea-surface waves. It consists of a weighted pole below which a disk is suspended at a depth sufficiently deep for the wave motion associated with deepwater waves to be negligible. The pole will then remain nearly as if anchored to ...