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Appendix I
Glossary
ACCELEROMETER.—An instrument used
to measure changes in velocity.
AFTER TRUCK.—The highest part of the
aftermast.
AGROUND.—When any part of a ship is
resting on the bottom. A ship runs
aground or goes aground.
AIR ALMANAC.—A periodical
publication of astronomical data, designed
primarily for air navigation.
ALTOCUMULUS.—A cloud layer (or
patches) within the middle level (mean
height 6,500 to 20,000 feet), composed of
rather flattened globular masses.
ALTOSTRATUS.—A sheet of gray or
bluish clouds within the middle level
(mean height 6,500 to 20,000 feet).
ANCHOR BALL.—A black circular shape
hoisted to indicate that the ship is
anchored.
ANCHORED.—Made fast to the bottom
by an anchor.
AYNGLE.—The inclination to each other of
two intersecting lines, measured by the arc
of a circle intercepted between the two
lines forming the angle, the center of the
circle being the point of intersection.
APPARENT TIME.—Time based upon the
rotation of the earth relative to the apparent
(true) Sun.
ARC.—Part of a curved line, as a circle.
The graduated scale of an instrument for
measuring angles, as a marine sextant.
ATMOSPHERE.—The envelope of air
surrounding Earth or other celestial body.
AZIMUTH.—The horizontal direction of a
celestial point from a terrestrial point. It is
usually measured from 000° at the
reference direction clockwise through 360°.
BAROMETER.—An instrument for
measuring atmospheric pressure.
BASE LINE.—The line between two
transmitters operating together to provide a
line of position, as in loran.
BEARING.—The horizontal direction of
one terrestrial point from another. It is
usually measured from 000° at the
reference direction clockwise through 360°.
BEARING CIRCLE.—A ring designed to
fit snugly over a compass or compass
repeater and provided with vanes for
observing compass bearings.
BEARING CURSOR.—A mechanical or
electronic bearing line of a plan position
indicator type of display for reading the
target bearing.
BEARING RESOLUTION.—The
minimum angular separation in a horizontal
plane between two targets at the same
range that will allow an operator to obtain
data on either individual target.
AI-1
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