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Old 02-13-2003, 08:02 PM
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kush kush is offline
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Moon's Orbit.

Juro,

Explaining tides is a tricky concept at best, in fact the text I use for my Geog 12 class at high school handles it by omission! As far as I'm aware there are always 2 high and 2 low tides, it is just that the difference between them is less in some tropical locales.

The tilt of the Earth on its axis remains constant (parallelism of the axis) so it will not effect the tides. The moon's orbit however, is 5 degrees off the equatorial axis of the Earth. What this means is that there are only 2 times during the lunar month when the moon is directly over the equator, the rest of the times it varies as much as 5 degrees away from the equator.

The effect of this is the difference between the height of the 2 daily tides (diurnal). When the moon is furthest north in its orbit it causes the tidal bulge to cross the rotating Earth at different latitudes. The effect is that one high tide will be the high high tide and the next the low high tide ( this is where people get lost - a model or diagram really helps). This difference changes as the lunar month progresses and the pattern continually evolves as the earth-moon relationship changes.

This of course gets further complicated by the shape of the coastline as well as the sun-moon-earth positions - I guess I see now why my text just leaves well enough alone! :eyecrazy: .
For fishing, the best advice I can give someone trying to figure out when is best, is to start a log book and get out lots so you can rack up the data - when you get it figured - write a book!
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