Why is the tidal difference greater in some places than others?

Question

Why, for instance, does the Bay of Fundy have the highest tides in the world?

Answer 1

In addition to the moon's gravitational forces (which causes all tides), I believe the differences are due to the geometry of the water mass (i.e. how deep is it?) It seems that the deeper the water, the more water molecules that can be affected by the gravitational pull. It may also have be due to the coastline depths. It seems to be that a body of water would be most effected if a) deep water in the middle and then b) a long shallow shore where the water could recede the most.

This is just a guess based on logic.

.... sorry, I was wrong....here is the correct scientific answer:

The Highest Tides on Earth
Occur in the Minas Basin!!
The tides on Earth are strongly influenced, in addition to astronomical factors, by the sizes, boundaries, and depths of ocean basins and inlets, and by Earth's rotation, winds, and barometric pressure fluctuations. Tides typically have ranges (vertical high-to-low) of a metre or two, but there are regions in the oceans where various influences conspire to produce virtually no tides at all, and others where the tides are greatly amplified. Among the latter regions are the Sea of Okhotsk, the northern coast of Australia, the Bristol Channel on the west coast of England, and in Canada at the Ungava Bay in northern Quebec, and the Bay of Fundy between New Brunswick and Nova Scotia. The tidal ranges in these regions are of the order of 10 metres.


The highest tides on Earth occur in the Minas Basin, the eastern extremity of the Bay of Fundy, where the average tide range is 12 metres and can reach 16 metres when the various factors affecting the tides are in phase (although the highest tides occur typically a day or two after the astronomical influences reach their peak).

The primary cause of the immense tides of Fundy is a resonance of the Bay of Fundy-Gulf of Maine system. The system is effectively bounded at this outer end by the edge of the continental shelf with its approximately 40:1 increase in depth. The system has a natural period of approximately 13 hours, which is close to the 12h25m period of the dominant lunar tide of the Atlantic Ocean.

Like a father pushing his daughter on a swing, the gentle Atlantic tidal pulse pushes the waters of the Bay of Fundy-Gulf of Maine basin at nearly the optimum frequency to cause a large to-and-fro oscillation. The grestest slosh occurs at the head (northeast end) of the system. Because Earth rotates counterclockwise in the Norhern Hemisphere, the tides are higher in Minas Basin (Wolfville-Truro area) than in Chignecto Bay (Amherst-Moncton area).

Although it is the gravitation of the Moon and Sun that raises the tides, the energy in the churning waters is extracted from the rotational energy of Earth spinning on its axis. Near Annapolis Royal, Nova Scotia, a tiny portion of this energy is being converted into commercial electrical energy in the only tidal power plant in the Western Hemisphere. The peak output of the Annapolis Basin generator is 20 megawatts, about 1% of Nova Scotia's electrical power capacity.

Tidal friction both lengthens the day and increases the size of the orbit of the Moon. The day is lengthening by about 1 second every 50,000 years, imperceptible on a human time scale, but of profound significance to Earth's rotation over a few billiion years. If the Sun does not first incinerate our planet, in the distant future there will come a day that is as long as the lunar month (each then equal to about 40 present days) and a more distant Moon will stand stationary in the sky, as does Earth now in theh lunar sky. But this situation will not endure, for solar tides will still be present and will cause the Moon to approach Earth once more.

Answer 2

Tide


The tide is the cyclic rising and falling of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the Earth. Tides cause changes in the depth of the sea, and also produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation (see Tides and navigation, below). The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zone, is an important ecological product of ocean tides.

The changing tide produced at a given location on the Earth is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of the rotation of the Earth and the local bathymetry (the underwater equivalent to topography). Though the gravitational force exerted by the Sun on the Earth is almost 200 times stronger than that exerted by the Moon, the tidal force produced by the Moon is about twice as strong as that produced by the Sun. The reason for this is that the tidal force is related not to the strength of a gravitational field, but to its gradient. The field gradient decreases with distance from the source more rapidly than does the field strength; as the Sun is about 400 times further from the Earth than is the Moon, the gradient of the Sun's field, and thus the tidal force produced by the Sun, is weaker.

Contents [hide]
1 Tidal terminology
2 Timing
3 Tidal physics
3.1 Tidal amplitude and cycle time
3.2 Tidal lag
3.3 Alternative explanation
3.4 History of tidal physics
4 Tides and navigation
5 Other tides
6 See also
7 External links



((((There is SO much MORE!!!)))

Answer 3

It is a combination of several events occuring simultaneously.
1) the gravitational pull of the moon affects oceanic tides
2) oceanic tides influence oceanic currents
3) oceanic currents affect the flow and movement of water in all other major bodies of water connected to oceans, other than rivers that source their water from mountains and /or forests.
4) surface weather conditions, such as hurricanes, and sub-earth movements, such as volcanoes, affect both tidal and current flow
5) Land formations influence wind direction in many circumstances, such as cold air moving toward the equator then impacting a mountain range and diverts in the same direction all the time. This action sometimes defines surface weather conditions.

All of this information, plus a great deal more, is what causes tidal movement. Not only the moon. If water is always travelling in a clockwise direction around a bay and after following the circumference impacts on a land mass, the combined pressure of that flow of water will raise sea levels. The land mass probably wont last long under this kind of punishment, perhaps eroding after 500 years or 500 days. That would be defined by the density (hardness) of the matter and size of the land mass at it's narrowest point.

Answer 4

It has a lot to do with channel widths and depths.
For a fixed volume of water, the narrow and shallow will pile up more water than the deep and wide. After all, there are two tides a day, so the water cannot hang about, or it will miss the last bus home!! :-)

Answer 5

Tides are controlled by the gravitational pull of the moon. The closer it is the stronger. That's fisherman need to know when there is a full moon.

Answer 6

Time and tide waits for no man.
Actually, it has something to do with the moon....

Answer 7

The gravitational pull of the moon.