visibility

n. quality of being clearly seen; distance to which one can see clearly (Meteorology); state or quality of providing an unobstructed view

In meteorology, visibility is a measure of the distance at which an object or light can be clearly discerned. It is important to all forms of traffic: roads, sailing and aviation. Meteorological visibility refers to transparency of air: in dark, meteorological visibility is still the same as in daylight for the same air. Aviation. In aviation, visibility is defined as the greater of:a) the greatest distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognized when observed against a bright background;b) the greatest distance at which lights of 1,000 candelas can be seen and identified against an unlit background.
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Noun
1. quality or fact or degree of being visible; perceptible by the eye or obvious to the eye; "low visibility caused by fog"
(synonym) visibleness
(antonym) invisibility, invisibleness
(hypernym) perceptibility
(hyponym) conspicuousness
2. degree of exposure to public notice; "that candidate does not have sufficient visibility to win an election"; "he prefers a low profile"
(synonym) profile
(hypernym) salience, saliency, strikingness
3. capability of providing a clear unobstructed view; "a windshield with good visibility"
(hypernym) clearness, clarity, uncloudedness

(n.)
The quality or state of being visible.
  

[ICAO]
The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night.

a. Flight Visibility-The visibility forward from the cockpit of an aircraft in flight.

b. Ground Visibility-The visibility at an aerodrome as reported by an accredited observer.

c. Runway Visual Range [RVR]-The range over which the pilot of an aircraft on the centerline of a runway can see the runway surface markings or the lights delineating the runway or identifying its centerline.

 

The ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and prominent lighted objects by night. Visibility is reported as statute miles, hundreds of feet or meters.
(Refer to 14 CFR Part 91.)
(Refer to AIM.)

a. Flight Visibility
The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.

b. Ground Visibility
Prevailing horizontal visibility near the earth's surface as reported by the United States National Weather Service or an accredited observer.

c. Prevailing Visibility
The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle which need not necessarily be continuous.

d. Runway Visibility Value (RVV)
The visibility determined for a particular runway by a transmissometer. A meter provides a continuous indication of the visibility
(Reported in miles or fractions of miles) for the runway. RVV is used in lieu of prevailing visibility in determining minimums for a particular runway.

e. Runway Visual Range (RVR)
An instrumentally derived value, based on standard calibrations, that represents the horizontal distance a pilot will see down the runway from the approach end. It is based on the sighting of either high intensity runway lights or on the visual contrast of other targets whichever yields the greater visual range. RVR, in contrast to prevailing or runway visibility, is based on what a pilot in a moving aircraft should see looking down the runway. RVR is horizontal visual range, not slant visual range. It is based on the measurement of a transmissometer made near the touchdown point of the instrument runway and is reported in hundreds of feet. RVR is used in lieu of RVV and/or prevailing visibility in determining minimums for a particular runway.
1. Touchdown RVR
The RVR visibility readout values obtained from RVR equipment serving the runway touchdown zone.
2. Mid-RVR
The RVR readout values obtained from RVR equipment located midfield of the runway.
3. Rollout RVR
The RVR readout values obtained from RVR equipment located nearest the rollout end of the runway.
(See ICAO term FLIGHT VISIBILITY.)
(See ICAO term GROUND VISIBILITY.)
(See ICAO term RUNWAY VISUAL RANGE.)
(See ICAO term VISIBILITY.)