DICTIONARY OF GEOPHYSICS, ASTROPHYSICS, and ASTRONOMY

monsoon climate
(1) sea-continent monsoon, (2) high level monsoon,
(3) plateau monsoon, and (4) planetary
monsoon. Every monsoon phenomenon is the
result of mixing these four types. According to
the latitude distribution, monsoons can be divided
as tropical monsoons, sub-tropical monsoons,
and temperate monsoons. The Indian
monsoon is caused by the seasonal change of
planetary wind belts which is enhanced by the
influence of sea-continent distribution effects,
and the eastern Asian monsoon is caused mainly
by sea-continent distribution factor. The Tibetan
Plateau is a major plateau monsoon region
which is due to its huge plateau’s orographic effects.
Other major areas of monsoons are southeastern
Asia, the west African coast (latitude
5 ◦ N-15 ◦ N), and northern Australia.
monsoon climate A climate associated with
the tropical regions of the Indian Ocean, Southwestern
Brazil, and northwest South America.
Characterized by high annual temperatures (≥
27 ◦ C), heavy high sun (summer) rain, and a
short low sun (winter) dry period. Total annual
rainfall is approximately 3 m.
month The period of one revolution of the
moon about the Earth or the calendar unit approximating
this. A “tropical month” is the period
between successive passages by the moon
of the vernal equinox (27.32158214 days of
mean solar time). A “sidereal month” is the period
between two successive transits through the
hour circle of a fixed star (27.32166140 mean
solar days). An “anomalistic month” is the
period between two successive transits of the
moon through its perigee (27.5545505 mean solar
days). A “draconitic” or “nodal month” is the
period between successive passages through the
ascending node of the moon’s orbit (27.212220
mean solar days). A “synodical month” is the
period between two identical phases of the moon
(29.5305882 mean solar days).
moody diagram A diagram for determination
of a dimensionless friction factor which appears
in the Darcy–Weisbach equation for description
of head loss in a full conduit carrying
a fluid. The friction factor is generally determined
graphically once the Reynolds Number
© 2001 by CRC Press LLC
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for the flow and the relative roughness of the
pipe are known.
moon (1.) Any natural body which orbits a
planet. The term “moon” is often used synonymously
with “natural satellite”. A moon can actually
be larger than some planets (as is the case
with Ganymede, Titan, and Callisto all larger
than Mercury and Pluto).
(2.) The twin planet of the Earth. The
airless satellite of Earth of radius 1740 km,
mass 7.35 × 10 22 kg, orbital semimajor axis
3.844 × 10 5 km, eccentricity 0.0549, albedo
0.07. The moon is tidally locked to synchronous
rotation to the Earth.
Dating of returned lunar rocks gives an age of
2.5 × 10 9 years ago for the oldest lunar surface.
The surface shows evidence for heavy meteor
bombardment ending about 3.5×10 9 years ago.
The moon is responsible for the majority of
tidal effects on the Earth. Phases of the moon
occur because its orbit is close to the ecliptic and
carries it from positions between the Earth and
the sun, when the side visible from Earth is unilluminated,
to positions beyond the Earth from
the sun, where the side visible from Earth is fully
illuminated. Because the moon’s angular size on
the sky is closely the same as the sun’s, it may
cause solar eclipses — the shadow of the Moon
on the Earth (when its orbit crosses the ecliptic
at new moon). Lunar eclipses occur when
the moon moves through the Earth’s shadow
in space; they occur when its orbit crosses the
ecliptic at full moon.
moonbow A rainbow that arises from the
refraction and reflection of moonlight on rain
drops or mist. Because of the faintness of the
source (moonlight), its colors are usually very
difficult to detect.
moraines Glacial deposits of unconsolidated,
unsorted material left at the margin of
an ice sheet. Several types of moraines are recognized.
Ground moraines are deposits of material
with no marked relief. This material is believed
to have been transported at the base of the
glacier. A lateral moraine is a moraine formed
along the side of a valley (alpine) glacier and
composed of rock scraped off or fallen from the
valley sides. A media moraine is a long strip of