Tides and Amphidromic points

[ex Elly 245]

Interesting article about tides around New Zealand.

There is an amphidromic point in Oteranga Bay near Wellington, where there is no tidal movement.
Plus, how the tides in French Pass can kill John Dories.

https://www.stuff.co.nz/national/explained/300651952/explained-the-new-zealand-beach-where-the-moon-doesnt-move-the-sea

 

 

[Romany 162]

.."the tides in French Pass can kill John Dories"..

& not just fishes by the sounds of it. I have been through that gap in a yacht - it looked scary even from the safety of big white floater, so I am not sure what would possess someone to actually jump in .

 

 

[Black Panther 1,745]

Papeete only has one high tide per day at noon.

[DrWatson 382]

On 5/08/2022 at 6:00 AM, Black Panther said:

Papeete only has one high tide per day at noon.

Cool -it’s really  that far from everywhere else

[Black Panther 1,745]

Distance is not the issue. Think of Thor standing in one spot swinging his hammer, as the hammer crosses the ocean tides go up and down, more so the further you get from Thor. Bur where Thor is standing there is little or no movement.  Thor is standing in Papeete.

 

There are several Thors.

[CarpeDiem 520]

Maybe I have not read enough or watched enough Marvel to understand Thor  

While I am certain it's perfectly valid, here's an alternative...

Think of it like carrying a shallow tray of water.  As you walk the water swishes from left to right up the sides, there is a middle, or fulcrum, point where the water hardly moves at all. Polynesia is located at the fulcrum point for the Pacific basin, (nothing to do with the equator), resulting in almost no tidal movement.

Tahiti, and Polynesia have no lunar tide.  The tide is about 20cm-30cm and is caused by the sun.

You'll get two high tides per 24hour day.

 

 

[Black Panther 1,745]

Methinks you guys are carrying the metaphor a little far

[Black Panther 1,745]

Try this

 

Near Tahiti though the lunar tide is cancelled because of an interesting phenomena called an amphidrome, or amphidromic point. As the lunar tidal swell passes around the earth and through the ocean basins, it gets broken up into lots of smaller swells, bouncing off continents and islands along the way, and it also gets affected by the Coriolis Force which bends it north and south. The ultimate effect is that there are places where a crest of the lunar swell meets a trough of the lunar swell, and cancels the tide out completely and these are the amphidromes. So with a lunar amphidrome located here we just have a solar tide, which is weaker, thus lower in amplitude, and locked into our normal 24 hour solar day. As you move away from Tahiti, into the Tuamotu Archipelago for instance or to the Marquesas, you get away from this amphidrome and the lunar tides begin to play a stronger role in the tidal cycle. 

[Steve Pope 253]

The Mediteranian basically has no tide, any rise or fall is related to barometric pressure. It does have currents though, usually 6 hourly + - with very little time between the changes of direction, very noticeable in restricted waters. Between the mainland and the island of Evoia (Greece) for example or the straits of Sicily, (between Sicily and the toe of Italy being 2 of the more prominent ones). I believe the water comes into the Med from the Atlantic on the Spanish side and goes out on the African side and takes 7 years for 1 complete circulation, and then is also the water coming from the Black sea also adding to the flow.

[Jon 407]

Current enters the Med from the Atlantic through the Straights of Gibraltar at or near the surface right across but stronger on the northern side

Theres a counter current running out but down deep, it’s only 7nm wide but over 500m deep

When we came out there was 25kt W blowing and the current was 3 to 4kts

[Fakeflip 0]

French pass is an amphidromic node... it is called Te Aumiti... a giant hole into the abyss which sucks water into the Earth and keeps the level to avoid flooding. 

 

 

 

 

 

 

 

In Italy as someone mentioned above there is another one, called Charybdis, in the strait of Messina. Another big hole that sucks an enormous amount of water from the Mediterranean. 

 

 

 

In USA, the Old Sow, in Canada The Skookumchuck narrows and Devils Hole.... in The UK you can find a huge one called Corryvreckan. In Norway the Moskenstraumen and Saltstraumen very close together. In Japan there are 3... Naruto, Kurishima and an unknown in the strait of Tushima.

 

There are many other amphidromic points in deeper water that do not produce whirlpools on the surface, like Gibraltar... we can't find the whirlpool probably because it's much deeper,  around 900m.

Tides are not produced by any magical force, like gravitational pull, this is BS. Tides are generated by underwater springs,  just like the ones that produce rivers on land,  but at a much higher pressure due to depth.

This is because Earth is a closed system immerse in Water,  where water springs fresh and gets sucked out salty... it gets purified God knows how and is Injected inside again through a pressure system of Heron Fountain...