The tide and the Wadden Sea

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tide & landscape

THE TIDE AND THE WADDEN SEA WHAT IS UP AND WHAT IS DOWN?

In the Danish part of the Wadden Sea, the daily difference in the sea level of up 2.5 meters. The tide and the Wadden Sea are inextricably linked since the changing sea level affects the landscape, the flora and the fauna plus man’s utilization possibilities. From Den Helder in Holland to Blåvand in Denmark, ca. 5,200 km2 of seafloor is exposed and flooded by 14 km3 sea water twice daily which, in the Danish part of the Wadden Sea, creates a daily difference in the sea level of up 2.5 meters. The tide occurs because the earth and the moon affect each other interrelationally. The sun’s contribution is not, however, without significance. So, one needs to look at things from a larger perspective while taking a good look at the solar system in order to understand why the sea level at the Wadden Sea rises and falls several meters approximately every six hours.

Astronomical waves

The moon’s orbit around the earth depends on two forces that each pull in a different direction while also affecting the oceans. The celestial bodies are pulled towards each other due to gravity, which is a universal, physical phenomenon that causes all bodies with a mass to attract each other. The pull of the moon can therefore be measured anywhere on the earth, but is strongest at the point nearest the moon and weakest on the side of the earth furthest from the moon. Why the moon does not crash towards the earth is

Experience the tide in ... SPRING

SUMMER

AUTUMN

WINTER

Tripping on the tide It takes ca. 13 hours for a tidal wave to move from Den Helder in the Netherlands to Blåvandshuk.

due to its orbit around the earth, which means that the gravitational pull is counterbalanced by an outwardly effective energy called the centrifugal force. This force is known from, among other things, carrousels and can be felt as the force that makes you hold on to the bar, so you are not hurled off. In the earth/moon system, the mutual rotational point is ca. ¼ inside the part of the earth nearest to the moon, so on the earth the centrifugal force is strongest at the point furthest from the moon. The tidal waves on earth occur because the ocean: • On one side of the earth is more attracted to the moon and therefore not hurled so far away • On the other side of the earth is hurled further away from the earth and therefore less attracted by the moon

Ulrik G. Lützen, Vadehavets Formidlerforum & Bent Jacobsen, NaturKulturVarde Translation: Nanna Mercer, Sirius Translation

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