Tides

[Houdini]

I work in the city and usually go down to Darling Harbour in my lunch break.

My lunch hr is always 12-1pm, yet the water level varies every day. Some days the water level is really low, other times it is nearly as high as the boardwalk around the waters edge. The difference appears to be as much as 2-3m.

I always thought the moon afftected the tides. Can anyone explain why there is such a difference between the water level at the same time each day?????????

Thanks

 

[El Diablo]

This site can be handy for questions http://science.howstuffworks.com/

ou might find your answer here http://science.howstuffworks.com/question72.htm

 

[Houdini]

Thanks El Duque, found the following from the link you posted -


Oddly, the tide is high (and also low) twice a day! If the gravity from the Moon--on the Moon's side of the Earth--causes the tide to be high, then how can the tide be high when the moon is on the other side of the Earth?

The Moon's gravity pulls directly toward the Moon, but it also pulls water toward an axis. That's an imaginary line running through the center of the Moon and the center of the Earth.

Water is drawn toward the Moon and toward the axis line; thus, high tide on the side of the Earth opposite from the Moon occurs at about the same time as high tide on the Moon's side of the Earth.



This other high tide, although high, is not as great as the high tide on the Moon's side of the Earth. Therefore, there is one "higher high tide" and one "lower high tide," as well as one "higher low tide" and "lower low tide" each day.

To complicate things even further, according to the US National Oceanic Service, there are over 30 variables in the Quoddy Loop which affect the amplitude of the tides, making tidal predictions a complicated task!

 

[Encurly]

As to why the tides are at different times each day, that's because the moon's in a different place each day, as it moves through its phases. The moon comes a bit less than an hour later each day, causing each tide to be the same amount later each day.

The other major effect on tides is the Sun. While it's a lot further away, it's a big bugger, and so it has a secondary effect on the tides. Basically, the position of the moon determines when the tide is, the position of the sun determines how big the tide is. When the sun and moon are along the same axis - new moon and full moon - the tide range is large. When the sun and moon are pulling at right angles to each other (half moon), the sun is dragging up the low tide, so the tide range is smaller.

 

[Ultima]

Hehe, I could have answered that better than the webpage

 

[Anonymous]

Hehe, I could have answered that better than the webpage

Thats great. The more info the better... lets hear it.

 

[MR GEORGE]

thanks did not know that learn something everyday.