CONDENSATION —The physical process by which a
vapor becomes a liquid. This process releases heat
energy.
CONDUCTION—Transmission of energy through a
substance by direct molecular contact.
CONVECTION—Motions in a fluid, such as the
atmosphere or water, which are predominantly
vertical, resulting in a vertical transport of mass and
eventually in a mixing of properties and energy.
CYCLONIC—Any rotational movement in a
counterclockwise manner in the Northern
Hemisphere, or a clockwise manner in the Southern
Hemisphere.
D
DASI—Digital altimeter setting indicator (Navy).
DDN—Defense data network.
DIURNAL—Any change that follows a daily pattern,
completing one cycle on a daily basis.
DMS—Position given in degrees, minutes, and seconds
of latitude and longitude.
DRIBU—Drifting buoy.
DSN—Defense switched network, an upgrade and
name change to the automatic voice network
(AUTOVON).
E
ETAGE—The layers of the atmosphere by which the
different genera of clouds are identified.
EVAPORATION—The change of state process by
which a liquid or a solid is transformed into a
gaseous state. This process requires the addition of
heat to the substance.
F
FAA—Federal Aviation Administration.
FAX—Short form of facsimile, referring to weather
facsimile or a telefacsimile transmission.
FLOES—Pieces of ice broken loose from a sheet of ice
that originally formed in the sea (frozen sea water).
FNMOC—Fleet Numerical Meteorology and
Oceanography Center, Monterey, California.
FRONT—The interface or transition zone between two
air masses of different density. Since temperature
is the most important regulator of atmospheric
density, a front almost invariably separates air
masses of different temperature.
FRONTAL SURFACE—Refers specifically to the
warmer side of an air mass transition zone, and
slopes in the vertical toward colder air.
FRONTAL SYSTEM—Simply a system of fronts as
they appear on a surface analysis or prognosis chart.
FRONTOGENESIS—The formation of a front.
FRONTOLYSIS—The dissipation or weakening of a
front.
G
GEOPHYSICS—Used to mean working with the
physical properties of both the air, land, and water,
this term is occasionally used to describe the
occupational field of Navy and Marine Corps
weather personnel.
GEOPOTENTIAL HEIGHT—The height of a given
point in the atmosphere calculated with respect to
the energy in the column of air beneath the point,
relative to sea level. In other words, an
approximation of the height based on measured
temperatures, pressures, and humidity content of
the supporting air column, and not necessarily an
exact measured height.
GHSI—General heat stress index, similar to apparent
temperature.
GMT—Greenwich mean time, a term replaced by
Coordinated Universal Time (UTC).
GPM—Geopotential meters, also gallons per minute.
GUST—A brief, rapid increase in wind speed.
H
HECTOPASCAL (hPa)—A unit of 100 pascals used
to measure pressure, exactly equivalent to 1
millibar.
HF—High frequency.
HIGH—An "area of high pressure," referring to a
higher atmospheric pressure in the horizontal plane,
such as a surface isobaric chart, or an "area of high
heights," referring to higher heights in the vertical
plane, such as on a constant pressure chart.
HYPOTHERMIA—An abnormally low body
temperature.
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