Image description

The image shows the two phases that make up the natural process called the tide, respectively flood tide, left and ebb tide, right.

The moon, the Earth’s natural satellite, visibly influences the level of the seas and oceans at certain times of the year, due to its proximity to the Earth and the force of attraction.

Thus in the central part of the planet appears the flood tide, respectively the attraction of the Moon that passes over the waters here, surrounding the Earth on its orbit, determines the rising level of the affected seas and oceans.

The image on the left shows a rocky cliff, quite high, which has not been eroded by waves to collapse or become a beach, on which you can best see the change in sea level at flood tide.

The cliff is rendered on the left edge by oblique and parallel lines, and the water on its right by wavy texture.

On the water floats a motor boat, highlighted embossed, in which is a man standing on the right side.

The flood tide shows that the water covered more than half of the cliff’s height.

Compared to the image on the left, the one on the right shows the same elements, the cliff, the water, the boat and the man, but here the ebb tide phenomenon occurs, when the waters recede, the sea level drops and it is observed that more than half of the cliff is above the surface, the sea water reaching only to its base.

Explained on a geographical sketch, an ebb tide occurs at the poles of the planet, up and down, when, at the same time, at the equator is happening a flood tide.

General information

About seventy percent of our planet’s surface is covered by water. The waters of the seas and oceans are in continuous motion, forming waves. Waves are undulating movements of water- that is movements up and down. 

The factors that cause the appearance of the waves are many, but we remember the sea currents, the winds and the tides.

Tides are oscillations in sea and ocean levels that are repeated regularly. These oscillations have two phases: ebb and flow. 

The flow represents the increase in the water level and the covering of a strip of land, and the ebb tide is exactly the opposite, meaning the retreat of the water back to the open sea. Each phase lasts about twelve hours, so over the course of a day we will notice both the flow and the ebb.

The emergence of the tides is due to the gravitational pull of the Moon and The Sun exerted on the Earth’s seas and oceans. Because the distance between the Earth and the moon is smaller, the force of attraction of the Moon is more important in the production of tides than the force of attraction of the sun.

Tidal amplitude can reach no more than eighty centimetres in the open ocean, but it can also reach nineteen meters in narrow and deep bays. The bays are the parts of an ocean that ends in a wide opening of land. The large amplitude in the Black Sea at Constanta is about ten centimetres.

Along with solar and wind energy, the tides are a clean source of energy that can be converted into electricity. The energy resulting from the movement of water in the production of tides is called tidal energy.

This is the only energy resource obtained with the help of the Moon.
There are several solutions for converting tidal energy into electricity. The simplest method is the application of the principle of function of fun hydropower plants. Waves operate turbines, they rotate and transmit mechanical energy to electric generators. 

Did you know that tides affect not only the waters, but also the earth’s surface, only that this cannot be perceived by man? The earth’s crust rises and falls like the ocean water level, but the amplitude is only a few tens of centimeters.


  1. https://www.scientia.ro/univers/sistemul-solar/7659-cum-functioneaza-mareea-acelasi-
  2. https://www.green-report.ro/noi-tehnologii-energie-maree-valuri/
  3. https://ro.wikipedia.org/wiki/Maree
  4. https://ro.wikipedia.org/wiki/Golf
  5. https://www.descopera.ro/maratoanele-descopera/mari-intrebari/13166318-de-ce-marile-si-oceanele-lumii-au-flux-if-reflux

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