High tides

With our Celtic origins, we had to blog about high tides, spectacular in Brittany, especially during the equinoxes with low tides, suitable for fishing and collecting shells.

The equinox tides

The equinox is the time of year when the sun is at the zenith at the earth's equator. The earth is then at right angles (taking the poles) with the sun's rays. Day and night then have the same duration. Between the months of March and September, when night and day have the same duration, a phenomenon called the equinox tide, when the sea recedes very far and which makes the tides stronger, attracts fishermen but is also feared by residents, because of the high risk of flooding.

When the Sun passes through the equinoxes relative to the plane of the equator, its action is strengthened. For the tides, as for the movement of the stars, the same law applies: the law of gravitation. There is a reciprocal attraction of the moon and the sun which causes the waters to move. The mass of the earth attracts the moon which remains in orbit and vice versa, the mass of the moon creates a force which draws the earth and the oceans towards it. It’s gravity. The coefficient can reach 105 during equinox tides. During the summer or winter solstices, the sun is far from the plane of the equator, the tides are lower with a coefficient less than 100.

The solstice is the time of year when the sun's rays hit the Earth at the most tilted angle. The summer solstice is the longest day and the winter solstice the shortest.

The tides of the century

Every four and a half years, the equinox tides are particularly strong and can occur several times in a century, the sea receding very far. The tides of the century can reach coefficients ranging from 118 to 120.

Tide times

The site: SHOM the ocean à la carte, is a free site for finding out about tide times around the world (Marine Hydrographic and Oceanographic Service).