Tuesday, February 10, 2015

Tides and the Euripus Phenomenon, Chalkida – Euboea

One of the interesting characteristics of Chalkida, the capital city of Euboea (the second largest island in Greece), is the fact that every six hours the sea water rises (floods) and in the next six hours it goes down again (ebb). We have a period of 12hours or 4 phases in 24hours 50 minutes 30 seconds. The 5o minutes and 30 seconds difference from the 24 hours refers to the moon, due to the fact that the moon needs exactly this period of time to pass over the same place on Earth twice (Newton 1687).

Assuming that the Earth was still and consisted of sea water, the moon would create an enormous wave that would follow it to its rotation around the Earth. However, the reality is much different. The Earth surface consists of continents; the coasts and the morphology of the sea’s bottom contribute to the development of the phenomenon in different ways. The sun contributes to the tide phenomenon. The tide force depends on the position of the three bodies (sun, earth and moon).

The first who found out the cause of the phenomenon was Aristotle and Eratosthenes. The word ‘Euripus’ is used, which derive from two words eu- and -ripi (brash flow). The term Euripus is used internationally to signify streams with a strong rush. 

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