Minus Tides

[darkmark1967]

Hi all, just wanted some information about minus tides. I understand the principals of tides and variations in the low ( and high) tide heights, but don't quite understand what's meant by minus tides. If anyone can help or point me in the direction of a useful website that would be most appreciated ,
cheers all, Happy Hunting
Mark

 

[Bling]

Tides are a very complicated phenomenon! The tug of the moon's gravity is one of the strongest components to the tides, and in most places there are only two tides in a day. However, there are many forces acting on the oceans to produce tides. In addition to the pull of the moon (known to physical oceanographers as the M2 tidal component), the sun also has an affect on the tides (known as the S2 component). As well, the orbits of the moon around the earth, and the earth and moon around the sun are not perfectly circular, which causes the tides to vary over time. Furthermore, in shallow water the water tends to "slosh around" a bit- that affects the tides in varying ways, and can alter the resulting tidal patterns quite a lot (this would be the resonance you mentioned). Shallow water effects are generally responsible for odd tides (things like 4 tides in a day). iv found here at full moon the low tide will be greater than the dark of the moon in the month.

 

[bazooka]

As I understand it, think of the sea level as 0 (Mean Sea Level I think? MSL?). If the water level is below 0, it's a minus tide...not low tide by definition, but almost certainly the case. So if you have a -1.3 tide, the water level is 1.3 below "normal" sea level, or 0, or MSL.

Low tide doesn't necassarily mean minus tide either...every two weeks you may have half of the days stay above 0. I suppose it's theoretically possible to have a high tide that is in the minus range, but I've never seen it here. I'm no oceanographer (although I do have a BS in geography ), so I could be wrong, this is just as I understand it.

 

[Dig]

dont forget the wind...a decent low and a strong wind blowing in favor and you can have a tremendous low. Conversely a strong wind blowing the wrong way will push more water over area that would have been exposed... IMHO I think tide and current and wind are all factors to be studied.

 

[darkmark1967]

Thanks all for the infomation, think that bazooka answered it for me, and dig, we have a saying here in Norfolk UK about winds. When they are strong we call them "lazy winds", why? Because when they blow they're too lazy to blow round you and blow straight through you instead! They really do make a difference with beach hunting.
Happy Hunting to you All,
Mark