the Aviation Dictionary

components' leads or by means of insulated hook up
wire.
polar airmass - An airmass with characteristics
developed over high latitudes, especially within the sub
polar highs. Continental polar air (cP) has cold surface
temperatures, low moisture content, and, especially in
its source regions, has great stability in the lower
layers. It is shallow in comparison with Arctic air.
Maritime polar (mP) initially possesses similar
properties to those of ~ontinental~~olar air, but in
passing over warmer water it becomes unstable with a
higher moisture content. See also tropical airmass.
polar easterlies - Surface winds generated by polar
highs north of 60" N latitude.
~olar airmass ~olvurethan enamel
poles of a magnet -- The north and south poles of a
magnet where magnetic lines of flux leave the south
pole and reenter at the north pole.
polishing - The process of producing a smooth surface
by rubbing it with fine abrasive wheels, belts, or
compounds.
polyacrylonitrile (PAN)- The base material used in
manufacturing some types of carbon fibers.
polyconic projection -- A map projection where the
parallels of latitude are arcs of a circle centered on the
north or south pole and the meridians are straight lines
radiating from the poles as in the spokes of a wheel.
polyester fiber - A synthetic fiber noted for its
mechanical strength, chemical stability, and long life. It
polar front - The semi-permanent, semi-continuous
is used to make woven fabric for covering aircraft
front separating airmasses of tropical and polar origins.
structures.
polar front jet stream - One of two jet streams that
polyester resin - A synthetic resin, usually reinforced
commonly occur in the westerlies. Associated with the
with fiberglass cloth or mat, and used to form complex
polar front.
shapes for aircraft structures.
polar front model - An idealized representation of
events that follow the development of a frontal low.
polyethylene - A lightweight, thermoplastic resin
material with good chemical resistance. Polyethylene
The surface component of the model describes the
resins are used for making containers for liquids and
structure and behavior of fronts and airmasses in the
sheets of protective covering material.
lower atmosphere. The upper air part of the model
deals with ;he associated~develo~ment of troughs, polyethylene plastic material - A lightweight,
ridges, and jet streams.
thermoplastic resin material that has very good
chemical- and moisture-resistant characteristics. It is
polar track structure - A system of organized routes
used for plastic sheeting and containers.
between Iceland and Alaska that overlie Canadian
MNPS Airspace.
Poly-Fiber0 - A fabric woven from polyester fibers.
polarity - The property of an electrical device having
two different types of electrical charges: positive
(deficiency of electrons) or negative (excess of
electrons).
polarization - A degradation in chemical cell
performance, particularly in the case of Leclanche
cells, caused by gas formation and the resulting
insulation of portions of the pole area.
polarized capacitor - A capacitor that can only be
hooked up to direct current of the proper polarity.
Electrolytic capacitors are normally polarized, and are
labeled for proper polarity connection.
polarized light - Light that has all the light waves in the
same plane.
polarized receptacle - A receptacle that has its sockets
arranged so that the plug can only be inserted one way.
This is done either through the shape of the plugisocket
in two prong receptacles or by the arrangement of three
or more prongs.
pole - The designation given to the ends of a magnet.
pole shoes - The field assembly part of an electric
generator or motor.
Aircraft Technical Book Company
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http:llwww.ACTechbooks.com
polymer paint - A fast drying, water-based paint that
contains vinyl or acrylic resins. When the water in the
paint evaporates, it leaves a waterproof film of the
plastic resin.
polymerization - The process of joining two or more
chemicals with molecules of similar structure, forming
a more complex molecule with different physical
properties. In this chemical reaction, the material
essentially jells.
polymid - A translucent plastic material commonly
referred to as nylon.
polyphase alternating current - Three-phase AC
electricity produced by more than one set of generator
windings.
polyphase electric motor - An induction motor that
operates on two-phase or three-phase AC.
polystyrene - A transparent plastic used to make cell
cases for some nickel-cadmium batteries.
polyurethane enamel - A two-component, chemically
cured enamel finishing system noted for its hard,
flexible, high-gloss finish.