the Aviation Dictionary

mesoscale convective complex (MCC) meteorological visibility
mesoscale convective complex (MCC)- The nearly
circular clusters of thunderstorms 300 NM or more in
diameter. MCC develops primarily between the
Rockies and the Appalachians during the warmer part
of the year.
mesoscale convective systems (MCS)- A large cluster
of thunderstorms with horizontal dimensions on the
order of 100 miles. MCSs are sometimes organized in a
long line of thunderstorms (e.g., a squall line) or as a
random grouping of thunderstorms. Individual
thunderstorms within the MCS may be severe.
mesosphere - A layer of the atmosphere between the
top of the stratosphere or the ionosphere and the
exosphere (about 250-600 miles above the Earth).
metal - A chemical possessing most of the following
characteristics: usually rather heavy, with a bright and
shining surface, malleable, ductile, and a good
electrical conductor.
metal chip detector (MCD)- An electrical device for
warning the aircrew of ferrous particles in the oil.
Consists of two magnets separated by a narrow gap or
insulator. The detector is found in the bottom of the oil
sump. When ferrous particles from the oil are attracted
to the magnets and bridge the gap, a circuit is
completed and a warning lamp illuminates in the
cockpit.
metal fatigue - A method of work hardening or cold
working of a metal that results from flexing or
vibration and which increases the brittleness of the
material to its breaking point.
metal foil - A very thin sheet of metal such as
aluminum foil.
metal-matrix composites (MMC) - In composites,
fibers bonded together with a metal as the bonding
material.
metal spinning - A process of metal forming in which
sheet metal is clamped into a lathe along with the male
die. A shaping tool is used to force the spinning metal
against the die.
metal spraying - A method of covering or repairing a
material with a coating of metal. The metal to be used
for the coating is melted and sprayed out with hot,
high-velocity compressed air.
metal-film resistor - A resistor in which an oxide of
metal is deposited as a film onto a base material. The
type of metal and the thickness determine the
resistance of the device.
metallic - Having the nature of metal or containing
metal.
metallic ion concentration cell corrosion - Corrosion
that results from a concentration of metallic ions in the
electrolyte. The area of high concentration of metallic
ions is the cathode.
metallic pigment - Extremely tiny flakes of metal
suspended in paint to produce a sheen.
metallic ring test - A test for delaminations in a bonded
structure in which a coin or similar object is used to tap
on the surface. If the bond is good, a metallic ringing
sound will be produced, however, if it is delaminated, a
dull thud will be heard.
metallizing - 1. To replace the fabric covering on an
aircraft structure with sheet metal. 2. A method of
metal overlay or metal bonding to repair worn parts
metallurgy - The science and technology dealing with
metals and their use.
metalworking tools - Machines and tools used in the
construction and repair of sheet metal structures.
metal oxide rectifier -An electronic device that enables
metamerism index - A measurement used for scientific
color matching. It indicates the way - a pigment - - will
look under varying light conditions.
one-way flow of current through the flow of electrons
from the base material to an oxide layer, but not from
the oxide layer to the base material.
metal oxide semiconductor capacitor - An electronic
device that utilizes metal oxide as a dielectric to create
capacitance.
metal oxide semiconductor field effect transistor
(MOSFET) - A semiconductor whose gate is
insulated from the channel. The MOSFET was
originally called the insulated-gate FET (IGFET). The
MOSFET has an extremely large input impedance.
Because the insulating oxide layer is extremely thin,
the MOSFET is susceptible to destruction by
electrostatic charges. Special precautions are necessary
when handling or transporting MOS devices.
metal sheath - A close-fitting metal cover.
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METAR - The international weather reporting code that
will be introduced in the U.S., after June 1, 1996.
metastable compound - A chemical compound that has
only a slight margin of stability.
meteor - A small particle of matter in the solar system
visible only as ii burns due to the high temperature
caused by friction as the meteor falls through the
Earth's atmosphere.
meteorological impact statement - An unscheduled
planning forecast describing conditions expected to
begin within 4 to 12 hours that can impact the flow of
air traffic in a specific center's (ARTCC) area.
meteorological visibility - A measure of horizontal
visibility in a given direction near the Earth's surface,
based bn sighting of objects in the daytime or
unfocused lights of moderate intensity at night.