Amphidromic point

As Amphidromie (from Greek ἀμφίδρομος ἀmphίdromos "rotate " ) refers to the course of a tidal wave in a marine basin in which to run around the phase lines of a star around a place. At this point amphidromischer occurs no tidal range. The tidal waves run clockwise or counter -clockwise around the amphidromischen points.

Physical relationships

Physically, it is Kelvin waves. The large Nordsüdausdehung the land masses of the Old World and America prevents smooth movement of the tide waves around the globe. Instead, the attracting forces of the sun and moon in the different ocean basins maintain one or more standing waves. The Coriolis force offset these standing waves in rotation ..

The extension of a Amphidromie depends on the speed with which to move the rotary shaft. This Wellengeschwindigkeikt C is proportional to the square root of the water depth t.

Within a Amphidromie the height of the tidal wave takes ( tidal range ) with the distance to its center. This explains why the tides on the east coast of England are more pronounced than in Cuxhaven.

Shallow sea North Sea

The North Sea has an unusually high density amphidromischer systems, three side by side in a small area because of their small depth. Their centers are located in the southern part of the peninsula between the English East Anglia and Holland, in the middle on the Jutland Bank between northern England and the Danish Jutland, and to the north off the coast of Norway to Stavanger.

Deep seas

In the deep oceans, the tidal waves rotate at several hundred kilometers per hour. Since wave peaks and troughs have stretches of often over a thousand kilometers and according gentle slopes there are rises and falls, the level at each coastal town of deep ocean faster than at the shallow North Sea. Also horizontal water movements are not faster.

Maps of

The two pictures show the amphidromischen systems of the oceans and the North Sea. The star- emanating from the points amphidromischen phase lines connect points of equal Tidenstands. This means, among other things occur to the connected places high and low water simultaneously. In the world map the curved black arrows illustrate the direction of rotation. Length and position of the arrows describe a period of six hours, which is about half a Tidenperiode. The surface colors represent the amplitude of the tidal wave dar. In the map of the North Sea, the flow direction is indicated with gray-blue arrowheads, and the synchronicity with an exemplary hour episode, see also table of selected Tidenhübe on the southern North Sea.