DICTIONARY OF

Inversion 182 Isohel
Inversion. Used in meteorology to denote that temperature increases with height above
surface of Earth. In tides, is a rise in water level with a rise in barometric pressure.
Inverted Tide. Occurrence of low water at the same time as Moon's transit at the place.
Invoice. Document sent by shipper to Customs authorities. States nature, quantity and value
of goods shipped.
Inwale. Name sometimes given to the internal fore and aft stiffener running along inboard
side of upper strake of a boat. More usually called 'gunwale'.
Inward Clearing Bill. Document issued by Customs authorities when ship has been
searched for unentered goods, stores checked and formalities complied with.
Iridium. Extremely hard metal used for compass pivots.
Irish Pendant. Nickname for a rope end, or yarn stop, blowing about in a wind. More
correctly, is any flag, pendant or ensign with a frayed fly.
Ironbound. Said of shore having rocky cliffs and no safe landing place.
Ironclad. Early name for warships whose wooden sides were sheathed with iron. Name
persisted after hulls were entirely of steel.
Iron Wire Rope. Non-flexible rope made of small iron wires and no hearts. Used for
standing rigging and other purposes in which extension due to stress cannot be tolerated.
Irradiation. Apparent increase in size of a heavenly body caused by the brightness of its
light.
Isaz. Short name for a line of iso-azimuth.
Isallobar. Line, on a meteorological chart, passing through all positions at which pressure
changes were similar during a given period.
Isallobaric Wind. Wind component that is due to changing pressure gradients.
Isentropic. Adiabatic.
Isherwood System. Shipbuilding method in which continuous longitudinal framing is the
dominant feature.
Iso. Prefix meaning 'equal'.
Iso-Azimuth. Equal, or similar, in azimuth.
Isobar. Line, on a meteorological chart, passing through all places having the same
barometric pressure.
Isobath. Line, on a chart, passing through points having the same depth.
Isoclinic Line. Line passing through all positions on Earth that have the same value of
magnetic dip.
Isodynamic Line. Line passing through all places on Earth having the same value of
magnetic force.
Isogonal, Isogonic, Line. Line drawn through all positions on Earth having the same
magnetic variation.
Isohel. Line, on meteorological chart, passing through all places having the same period of
sunshine.