The phenomenon of the tides has been studied since antiquity.
In this section we will try and answer these questions clearly and precisely.
The tides are periodic oscillations in the level of the sea which come about as a result of the attraction of the Sun and the Moon on the liquid particles of oceans. The effects of the celestial bodies superimpose and the result constitutes the generating force of the tides.
The relation of the tides with the principle of universal gravitation has permitted the quantitative definition of these forces.
Applying Newton's Law we deduce that the Moon is so close to Earth that the action of the Sun, despite its enormous mass, does not exercise even half of the effects of the Moon. In tide simulations we can graphically prove how the resulting tide is principally provoked by the action of the moon. This explains the great relationship of the tides with the lunar phases.
However, tides undergo great variations depending on the geography of the coast in any given area. This is why, in order to produce reliable tide forecasts at any point of the planet, we use mareographs, which record the sea levels at different times of day and we take advantage of the cyclical nature of the tides to forecast the tide tables.
Given that the only factors we take into consideration in tide formation are the Moon and the Sun, the Moon due to its proximity and the Sun due to its mass, they tend to be called astronomical tides.
However, despite the fact that the Sun and above all the Moon are the fundamental factors in the formation of tides, we must also know that other atmospheric phenomena, the wind and the rain also provoke variations in sea level, although due to their unpredictability in the long term, they are not taken into consideration in tide tables. With an atmospheric pressure higher than normal, sea levels will be lower than those forecast in the tables, and vice versa. In addition, a strong and constant wind which blows in the direction of the coast will produce higher tides than those forecast, while a wind in the opposite direction will provoke lower tides.