EARTH : the movements of the ocean:

 The movements of the ocean:

    The waves are born from the wind blowing over the ocean. Strong winds, lasting over great distances, give rise to the highest waves. When approaching the Earth, the base of the wave slows down in contact with the ground while its crest, which has kept its speed, bends and falls. Ocean currents, similar to underwater winds, move water along gigantic circular routes. Hot or cold, they have a great influence on the climate.

Moon influence:

    The tides result from the attraction of the Sun and the Moon. The Moon exerts a stronger attraction than the Sun, because it is located closer to the Earth. So, when the Sun, the Moon and the Earth are aligned, their gravitations add up and create extremely high or low tides (surge tides), and when the Sun and the Moon form a right angle to the Earth, attraction is lower and tides are smaller (deadband tides).

Intertidal zone! 

    Tides do not have the same amplitude on all coasts. At the edge of the Mediterranean, the height of the tide is 1 m, while in the Bay of Fundy, Canada, it is about 16 m: the sea exposes twice a day vast tracts of soil, temporarily leaving the boats on the sand.

The surf!

    Surfers use the power of the huge waves that break on the Hawaiian coasts to complete fantastic rides . A few champions with a sense of timing and perfect balance have even managed to surf on Jaws, the most dangerous wave in the world. Jaws, which can reach 18 m in height, surges along a reef off Maui (Hawaii). Most ocean waves are less than 3.7 m high.

The whirlpools!

    This type of vortex is formed where strong tidal currents meet. The phenomenon usually occurs when the sea engulfs in narrow passages between islands and continental areas. The water rushes at such a speed through the Saltstraumen Passage, in the northwest of Norway, that the noise it produces where the currents reverse is heard several kilometres away.

Streams rich in nutrients!

    The currents are moving in all directions. Those that rise from the depths bring to the surface nutrients essential to plankton (tiny animals and plants that live suspended in the water). Plankton multiply rapidly and serve as food for small fish. Off the coast of Peru, for example, it feeds huge schools of silver anchovies. Millions of these tiny fish are themselves caught by larger fish, birds and fishermen. Indeed, almost a quarter of all fish caught in the world come from this region.

The tsunamis!

    Do you remember the disaster of 26 December 2004 in Asia? More than 300,000 people living in Asia died that day, when a wave more than 10 m high, advancing at 800 km/h, engulfed their homes and villages. And like most tsunamis, or tidal waves, this one was due to an underwater earthquake. When shaking violently, the ocean floor gives rise to waves that move away very quickly in concentric circles. When they reach shallow areas, these waves accumulate and form a gigantic wall of water called a tsunami {large wave breaking into a Japanese port}.