If you have studied or are studying science, surely you have heard from time to time about tides. These large waves that cause the sea level to rise are a fairly common and popular phenomenon that many still do not fully understand.

If you have doubts and questions regarding this topic, keep reading this article. We will tell you, below, what the tides, why they occur are and how they occur so that you understand not only the causes and meaning of this phenomenon but also the consequences it can have.

What are tides and why do they occur

Simply explained, the rising and falling levels of the sea throughout the day are known as tides; that is, the rocking of the waves as they approach and move away. To understand how and why tides occur, you must bear in mind that different elements come into play:

  • Gravitational forces of the Moon.
  • Gravitational forces of the Sun.
  • Centrifugal force of the Earth caused by the movement of rotation and translation (that is, the movement it makes on itself and the movement it makes around the Sun).

Tides are produced by these forces of gravity. However, before going into detail explaining how the tides work, you should know that when we talk about this phenomenon, the gravitational forces of the Moon have more weight than those of the Sun, since on Earth we are further away from this star than of the Moon (the Moon, in fact, is 400 times closer to the Earth than the Sun).

How the tides are produced

To understand tides, you must keep in mind Newton’s law of universal gravitation, which reminds us that the gravitational attraction between two bodies is directly proportional to their masses and inversely proportional to the distance between the two bodies. That is, the greater the mass of an object and the closer one object is to the other, the greater the gravitational attraction between them. This is what happens, in this case, with the Moon and the Earth.

With this in mind, we understand that the closer the Moon is, the greater the force of gravity, and therefore on the side of the Earth closest to the Moon (as well as on its opposite side, due to the centrifugal force from the Earth) there will be high tide (high tide), while on the far sides, there will be low tide (low tide).

In other words: when there is high tide, what happens is that the Moon is on the vertical of an ocean and, therefore, it attracts the waters and they rise. The ups and downs of the sea will therefore depend on the attraction of the stars. In the following image you can see how the phenomenon works:

Types of tides that exist

There are several types of tides depending on the characteristics that we take into account. If we talk about the height of the sea, we must consider, as we have seen in the previous section, the following types:

  • High tide: occurs when the sea reaches its highest point in the tidal cycle due to the proximity of the Moon. Also called high tide.
  • Low tide: when, on the contrary, the sea reaches its lowest level. Low tide is also called low tide.

But, if we take into account the different lunar phases, we will talk about the following possible tides:

Spring tides

They are those that occur during the full moon phase (when we can see the satellite completely) and the new moon phase (when, from Earth, it is not visible). During these phases, the Moon and the Sun are aligned and, therefore, the effects of the tides increase and are enhanced.

Neap tides

These types of tides occur during the waning and waxing lunar phases; when the Sun and Moon are not aligned and, therefore, the tides are less extensive.


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