An area of sky with a formation of rounded and isolated cirrocumulus or altocumulus resembling the pattern of scales on the back of a mackerel.

Related Terms


A representation, usually on a plane surface, of all or part of the surface of the earth, celestial sphere, or other area; showing relative size and position, according to a given projection, of the features represented. Such a representation intended primarily for navigational use is called a chart. A planimetric map indicates only the horizontal positions of features; a topographic map both horizontal and vertical positions. The pattern on the underside of extensive cloud areas, created by the varying amounts of light reflected from the earth’s surface, is called a sky map. A chart which shows the distribution of meteorological conditions over an area at a given moment may be called a weather map.


1) Bending a batten in a curve as a pattern to mark out the rounded shape required for a component in timber boat building. 2) A method of fitting longitudinal planking junctions.


As defined by the International Telecommunication Union (ITU), a transmitter in the aeronautical radionavigation service which radiates vertically a distinctive pattern for providing position information to aircraft.


Wide Area Network.


Area controlled by a VTS-Centre or VTS-Station


The amount of heat which passes through a unit area of a medium or system in a unit time when the temperature difference between the boundaries of the system is 1 degree.


Area established by Federal regulation in which dumping of dredged and fill material and other nonbuoyant objects is allowed with the issuance of a permit. Dump sites are shown on nautical charts.


Fairing lines added to a vessel's body plan. They take the form of straight lines (usually three in smaller craft) drawn diagonally from the centreline, to strike the area of the waterline. The projection a line drawn from the series of intersection points found (of diagonal & waterline) along the hull, gives an indication of the likely water flow across the structure.


An officially designated offshore area for the burning of chemical waste by specially equipped vessels. The depiction of incineration areas on charts (in conjunction with radio warnings) is necessary to insure that passing vessels do not mistake the burning of waste for a vessel on fire.


A reference system that permits the designation of the location of a point or an area on a map, photograph, or other graphic in terms of numbers and letters. Also called ALPHANUMERIC GRID.

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