Why is there a tidal up and down phenomenon?

Tide is the phenomenon of sea level rise and fall in an astronomical cycle.

The mutual attraction between the Moon and Earth tends to make them closer together. But this attraction is compensated by the centrifugal force of the Earth, as well as that of the Moon, around their inertial center.

At the center of the Earth, centrifugal force and attraction from the Moon complement each other. But this is not the case at some point on the ground because the two forces change in opposite directions: the farther away the center of the Earth - the Moon, the more centrifugal force it suffers will be, in on the contrary, the attraction of the Moon decreases with distance.

Therefore, the two forces do not compensate on the surface of the Earth and their difference is the source of the tide: at point A, centrifugal force is not enough to balance the attraction, so A tends to translate Move towards the Moon. Conversely, at point B the centrifugal force is greater than the force of the Moon, so B tends to leave it. That's why on Earth there are two tides every day.

This differential suction affects the entire surface of the Earth, but only the deformation of the ocean is easy to see, while the Earth's crust is so solid that its shape is difficult to change. This distortion increased when the Sun was in line with the Moon and the Earth, then adding its own tidal effect. Therefore, at the time of the new moon and the full moon , the tide is strongest.

Every day, there are 2 high tide and 2 low tide. Each day of the tide appears about 1 hour later than the previous day. Because every day, the Moon has to make a partial rotation around the Earth, so the Moon has a difference of 1 hour to return to the same point.

The map of the tide (sea level difference when the tide is rising and falling) is very different. In the oceans, this amplitude is 1m, in smaller and smaller seas it is less: about 30cm, but in estuaries and straits can be up to 17m.