Why are ocean tides greater in some areas? My son just
back from Cape Hatterus NC and he said he saw very small tide changes.
The gravitational attraction, primarily of the moon, causes the water in the
oceans to "rise" a certain amount, i.e. it bulges a bit on the side facing
the moon, and on the side facing away from the moon. If the shoreline is
long, wide and flat, this rise is spread out over a large surface area, so
the "rise" is small. If the shoreline is a gorge, surrounded on three sides
by cliffs there is no place for the water to go but UP, so the tide rises a
great height. If memory is correct, the bay of Fundy, I think in Nova Scotia
is the classic example.
It's really a bit more complicated than this because the tidal rise depends
on other things such a approaching hurricanes or typhons, and on the
landscape of the ocean floor off shore.
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Update: June 2012