Effect of tidal currents on the coast
The liquid particles of oceans placed in movement by the action of the Sun and the Moon describe closed orbits contained in vertical planes. The vertical movement constitutes the tide, the horizontal movement, much more important, is the current of the tide, which affects the entire depth of the water.
In high seas the current has little speed and is alternative, aimed in the direction of the propagation when the liquid surface is above average level, and vice versa. Close to the coasts, however, the nature of currents is profoundly perturbed and, in some cases, their speed may reach as much as 20km/h. In these cases where the currents are so intense, we would be obliged to replace our casting weights for spherical weights or even hooks in order to keep our fishing tackle in the same place.
The thermohaline circulation (THC) is generated by the difference in the density of seawater. The density difference is mainly caused by temperature (heat) and the salt content (salinity); the density decreases as the temperature increases, also increasing with the salinity, although the temperature also increases evaporation and therefore also increases the salinity.
This situation along with the rotation of the earth, among other factors, create the marine currents that act as thermal regulators worldwide and influence the climate, transporting heat from the tropics to the north and colder water from the north to the continent of Antarctica and the Pacific and Indian oceans through the depths.
Thermohaline circulation (THC)