The tide

The tide, the daily movement of the sea, is a universal phenomenon. For a long time, our ancestors believed that it was ruled over by the gods or by some obscure force. Then, from the seventeenth century onwards, Newton's law of Universal attraction and work by scientists such as Laplace or Poincaré proved that a particular force was indeed at work: the force exerted by the Moon and the Sun on the Earth.

The tide has a date with the moon

The Moon acts like a magnet on the oceans. Because of its proximity, its gravitational pull on the Earth is twice as strong as that of the Sun.
Their actions are combined in different ways depending on their respective positions:

•  Spring tides, also known as perigean tides, occur when there is a full or a new moon, when the Moon and the Sun are in a straight line with the Earth, thus strengthening their force of attraction.

•  Neap tides occur when the Sun and the Moon form a right angle with the earth (during the first and last quarters).

The highest tides in Europe

In addition to the attraction of the stars, the tides are also greatly influenced by the coastline. If the Bay of Saint-Malo can boast of staging the highest tides in Europe, it is also as a result of its geographical location. When the Atlantic Ocean, an incredible amount of water, rushes into the bottleneck of the English Channel, the waters come in hard and fast. The tidal range - the difference between the level of the sea at high and low tide - is more than 12 metres on average around the Corsair City. This is exceptional when you consider that in the Landes region in the South West of France, the tidal range is 5 metres and that the world average is only 2 metres!

"a tide of 100"

Using tidal coefficients (a ratio against the highest possible tide), professionals and amateurs alike can gain an idea of the size of the tide and thus avoid being taken by surprise when the tide comes in. This "scale" goes from 20 (lowest neap tide) to 120 (equinoctial Spring tide). Spring tides are those with a coefficient of 95 or more.

A short dictionary of Spring tide vocabulary