the sea tides

cm1179

cm1179

cm1179

Soldato
Joined
30 Sep 2009
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i can't get my head around why the sea goes in and out, though i think it is something to do with the gravitational pull of the moon?

can somoene explain it please? it's pretty surreal if you think about it ...
 
Yes. the moon pulls on the water closest to the moon, the sea then rises. If it rises in one place then it must fall in another. This gives tides.

Gross oversimplification.
 
It's not just water that is pulled but it's properties means it actually has an effect.

Although you need one hell of a body of water.
 
It's pretty simple and not surreal. Water is just being pulled by the moon. Add in orbits and earth rotation and you get regular tides.

http://en.wikipedia.org/wiki/Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth. The tides occur with a period of approximately 12 hours and 25 minutes, and with an amplitude that is influenced by the alignment of the sun and moon and the shape of the near-shore bottom.[1][2][3]

Most coastal areas experience two high and two low tides per day. One of these high tides is at the point on the earth which is closest to the moon. The other high tide is at the opposite point on the earth. This is because at the point right "under" the Moon (the sub-lunar point), the water is at its closest to the Moon, so it experiences stronger mavity and is raised. On the opposite side of the Earth (the antipodal point), the water is at its farthest from the moon, so it is pulled less; at this point the Earth moves more toward the Moon than the water does—causing that water to "rise" (relative to the Earth) as well. In between the sub-lunar and antipodal points, the force on the water is diagonal or transverse to the sub-lunar/antipodal axis (and always towards that axis), resulting in low tide.[4]
Click to expand...
 
tides.gif
 
Thing that gets me about this is that surely then the oceans are all at a bit of a slope...

So say where I live, the Estuary, when the tide's out, the water must all be squashed up to Kent and sloping towards Essex. Weird.
 
It's not just water that the gravitational pull of the moon has an effect on, the earth under your feet goes up and down as much as a foot due to the same force.
 
There is a giant inside of the earth that is trying to break out, fortunately for us, it is near impossible, however, this giant is not a quitter and keeps on pushing.
 
last i heard it happens when all the americans go for a dip at the same time, giving high tide. then they all get out again and low tide is again upon us
 
Jupiter's moon Io has tidal forces similar to that on earth, but its the land itself that's pulled towards Jupiter. If you could stand on Io you would see a 30ft tide of land coming at you :eek:

Thought some might find that interesting.
 
Its quite simple really;

By far the most important factor, effecting the movement of water across the ocean are tides. Tides are great bulges of water, caused by the mavity of the Moon, and Sun. Attracted by mavity, these bulges move around the Earth’s oceans, causing water levels to rise and fall. Typically water will rise for about six hours, followed by six hours of falling water depths.
 
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