Predicting Weather By The Moon - Xavier University Libraries

Weather By The Moon
ally accompanied, in summer, by new moons. Once again,
colder weather in winter more often applies around full
moons, when the northern declination plays host to the full
moon phase and the atmosphere is stretched at night.
The 27.5 day monthly cycle of lunar declination contributes
to the overall tidal effects. The closer the Moon
comes to being overhead, the more powerful are its effects.
The greatest possible astronomical tide-generating
force occurs when, at the same time, the Sun is at its Perigee,
the Sun and Moon are at Full or New Moon and both
the Sun and Moon have zero declination. This is called the
Nodal Cycle and happens about once in 1600 years. It happened
in 250 B.C., 1400 A.D, and it will occur again around
3300 A.D.
In the story so far, the Moon rises along the eastern
horizon and sets along that of the west, due to the real rotation
of the Earth from west to east. The Moon is also moving
in its orbit from west to east, so it seems to travel eastward
among the stars, covering about 13° per day. The apparent
path of the Moon is not very different from that of
the Sun - the angle between the two is only 5°, which is not
very much even though it is sufficient to prevent eclipses
occurring every month. The Moon wobbles, going around
the Earth from a northernmost point to a southernmost in
14-days, and then back up again. It also comes in closer
once per month, and has a corresponding furthest point away
two weeks later
Syzygy refers to the situation whereby the centers of
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