Every drop of water in the ocean, even in the deepest parts, responds to the forces that create the tides. No other force that affects the sea is so strong. Compared with the tides, the waves created by the wind are surface movements felt no more than a hundred fathoms below the surface. The currents also seldom involve more than the upper several hundred fathoms despite their impressive sweep.
The tides are a response of the waters of the ocean to the pull of the Moon and the more distant Sun. In theory, there is a gravitational attraction between the water and even the outermost star of the universe. In reality, however, the pull of remote stars is so slight as to be obliterated by the control of the Moon and, to a lesser extent, the Sun. Just as the Moon rises later each day by fifty minutes, on the average, so, in most places, the time of high tide is correspondingly later each day. And as the Moon waxes and wanes in its monthly cycle, so the height of the tide varies. The tidal movements are strongest when the Moon is a sliver in the sky, and when it is full. These are the highest flood tides and the lowest ebb tides of the lunar month and are called the spring tides. At these times, the Sun, Moon, and Earth are nearly in line and the pull of the two heavenly bodies is added together to bring the water high on the beaches, to send its surf upward against the sea cliffs, and to draw a high tide into the harbors. Twice each month, at the quarters of the Moon, when the Sun, Moon, and Earth lie at the apexes of a triangular configuration and the pull of the Sun and Moon are opposed, the moderate tidal movements called neap tides occur. Then the difference between high and low water is less than at any other time during the month.
Every drop of
water
in the ocean, even in the deepest parts, responds to the forces that create the
tides
. No other force that affects the sea is
so
strong. Compared with the
tides
, the waves created by the wind are surface movements felt no more than a hundred fathoms below the surface. The currents
also
seldom involve more than the upper several hundred fathoms despite their impressive sweep.
The
tides
are a response of the
waters
of the ocean to the
pull
of the Moon and the more distant
Sun
. In theory, there is a gravitational attraction between the
water
and even the outermost star of the universe. In reality,
however
, the
pull
of remote stars is
so
slight as to
be obliterated
by the control of the Moon and, to a lesser extent, the
Sun
.
Just
as the Moon rises later each day by fifty minutes, on the average,
so
, in most places, the time of
high
tide
is
correspondingly
later each day. And as the Moon waxes and wanes in its monthly cycle,
so
the height of the
tide
varies. The tidal movements are strongest when the Moon is a sliver in the sky, and when it is full. These are the highest flood
tides
and the lowest ebb
tides
of the lunar month and
are called
the spring
tides
. At these times, the
Sun
, Moon, and Earth are
nearly
in line and the
pull
of the two heavenly bodies is
added
together to bring the
water
high
on the beaches, to
send
its surf upward against the sea cliffs, and to draw a
high
tide
into the harbors. Twice each month, at the quarters of the Moon, when the
Sun
, Moon, and Earth lie at the apexes of a triangular configuration and the
pull
of the
Sun
and Moon
are opposed
, the moderate tidal movements called neap
tides
occur. Then the difference between
high
and low
water
is less than at any other time during the month.