marée

Marée refers to the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth. This phenomenon is known as tidal force. The Moon's gravitational pull is the primary driver of tides due to its proximity to Earth. The Sun also exerts a gravitational influence, but to a lesser extent.

Tides are broadly categorized into two main types: high tide and low tide. A high tide occurs when the sea level is at its highest point, and a low tide occurs when it is at its lowest. The time between successive high tides is approximately 12 hours and 25 minutes, and similarly between successive low tides. This cycle results in two high tides and two low tides approximately every 24 hours and 50 minutes, which is the lunar day.

The gravitational pull creates bulges in the Earth's oceans on the side facing the Moon and on the opposite side. As the Earth rotates, different locations pass through these bulges, experiencing high tides. The areas between the bulges experience low tides.

The amplitude of tides, or the difference between high and low tide, varies depending on geographical location, coastal shape, and the alignment of the Sun and Moon. Spring tides, which are the highest and lowest tides, occur when the Sun, Earth, and Moon are aligned (during new and full moons). Neap tides, with the smallest tidal range, occur when the Sun and Moon are at right angles to each other relative to Earth (during the first and third quarter moons). Tidal currents are the horizontal movements of water that accompany the rise and fall of the tide.