Other occasional phenomena, such as winds, rains, overflowing rivers and tsunamis cause sea level variations, also occasional, but can not be qualified as tides, because they are not caused by gravitational force or have periodicity.
Below are the main terms used in the description of the tides:
High tide or high tide: moment in which the sea water reaches its maximum height in the tidal cycle.
Low tide or low tide: opposite moment, when the sea reaches its lowest height.
The approximate time between a high tide and low tide is 6 hours, completing a cycle of 24 hours 50 minutes.
Flow: the flow is the process of slow and continuous rise of the marine waters, due to the progressive increase of the lunar or solar attraction or both attractions in the case of new moon and full moon.
Reflux: reflux is the process of descent of marine waters, slow and progressive, due to the decline of the lunar or solar attraction.
Race or tidal range: height difference between high tide and low tide.
Micromareal range: when the tidal race is less than 2 meters.
Mesomareal range: when the tidal race is between 2 meters and 4 meters.
Macromareal range: when the tidal race is greater than 4 meters.1
Tidal period: difference in time between high tide and low tide.
This is the tide: it is the moment when the level remains fixed at high tide or at low tide.
Current stoa: is the instant when the current associated with the tide is canceled.
Establishment of the port: it is the existing lag, due to the inertia of the hydrosphere, between the passage of the Moon by the meridian of the place and the appearance of the next high tide.
Age of the tide: it is the existing lag, for the same reason, between the passage of the full moon by the meridian of the place and the next highest monthly high tide.
Unit of height: average for 19 years (one nodal cycle or metón cycle) of the two maximum tidal races (equinoxes) of each year of the cycle.
Live tide, high or syzygy: are the tides that occur with the full moon and the new moon, when the Sun, Moon and Earth are aligned. The Living Tide that occurs during the New Moon phase is called the "Living Tide of Conjunction"; and the one that occurs while the full moon phase takes place is called the "Living Tide of Opposition."
Dead, low or quadrature tide: are the tides that occur during the phases of the Fourth Quarter and the Fourth Waning, when the positions of the Earth, the Sun and the Moon form an apparent angle of 90º.
Cotidales lines: the cotidales lines (of English tide: tide) are the lines that unite the points in which the high tide is simultaneous.
Amphipromic points or points of amphidromia: are areas towards which converge the cotidal lines and in which the amplitude of the tide is zero.
Standard port: these are the geographical points for which the prediction of date and height of tide is calculated and published.
Secondary port: geographic points of interest for the navigator but have not published a prediction calculation of tides, but a correction in terms of time and height that refers to a standard port and through which you can also determine the data tidal.
Tide tables: they are the annual publications with the daily prediction of the tidal heights. They provide, among other data, date, time and height of tide for different points along the maritime coast.
Then the area covered by water that is closer to the moon is attracted to it, while in another part of the water there is less attraction to be further away from the moon. In this way it is that the great masses of water of the seas and oceans somehow stretch or dilate and this is what produces the tides.
In this way we could also explain why there are no tides in the rivers, although this is not always the case, since in some cases under special circumstances tides may occur in lakes and rivers
This phenomenon is very noticeable in the coasts, where day by day the coastal limit moves in one direction and in another. This is called flow, when the water advances and ebb, when the waters are in retreat. Between one period and another it extends for 6 hours, so it is said that the tides are every 12 hours, the complete cycle
As the earth turns on itself every 24 hours, the tides follow the cycles of the day and every 6 hours occurs, which gives us 2 low tides and 2 high tides per day.
