A poorly developed corona, characterized by a bluish-white disk immediately around the luminary and a reddish-brown outer edge. An aureole, rather than a corona, is produced when the cloud responsible for this diffraction effect is composed of droplets distributed over a wide size-range. The diffracted rays approach the observer from a wide variety of angles, in contrast to the relative uniform diffraction produced by a cloud of more limited drop-size range. In as much as most clouds exhibit rather broad drop-size distributions, aureoles are observed much more frequently than coronas.


Related Terms

N TO THAT OF THE DIE OPENING. PARKWAY

A broad landscaped expressway which is not open to commercial vehicles.

MACHETE

A knife with a broad blade 2 to 3 feet (60 to 90 centimeters) long.

CONTAMINATION CONTROL

A broad subject which applies to all types of material systems (including both biological and engineering). It is concerned with planning, organizing, managing, and implementing all activities required to determine, achieve and maintain a specified contamination level.

BROAD

In appearance from the vantage point of a lookout or other person viewing activity in the vicinity of a ship, e.g., another ship off the starboard bow with her side facing the viewer's ship could be described as 'broad on the starboard bow' of the viewer's ship.

ABAFT THE BEAM

Any direction between broad on the beam and astern. See also FORWARD OF THE BEAM

ARCHIPELAGO

1. A sea or broad expanse of water containing many islands or groups of islands. 2. A group of such islands

NATIONAL GEODETIC VERTICAL DATUM

A fixed reference once adopted as a standard geodetic datum for heights in the United States. The geodetic datum now in use in the United States is the North American Vertical Datum of 1988. The geodetic datum is fixed and does not take into account the changing stands of sea level. Because there are many variables affecting sea level, and because the geodetic datum represents a best fit over a broad area, the relation- ship between the geodetic datum and local mean sea level is not consistent from one location to another in either time or space. For this reason the National Geodetic Vertical Datum should not be confused with MEAN SEA LEVEL.

BLUFF

A headland or stretch of cliff having a broad nearly perpendicular face

FORWARD OF THE BEAM

Any direction between broad on the beam and ahead

ON THE BEAM

Bearing approximately 090° relative (on the starboard beam) or 270° relative (on the port beam). The expression is often used loosely for BROAD ON THE BEAM, or bearing exactly 090° or 270° relative. Also called ABEAM.

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