Sea's Moviment

Sea's Moviment

Waves, tides and Currents

INTRODUCTION

Marine movements are all the displacements of water within seas and oceans, and they represent one of the fundamental aspects of Earth’s dynamics. They are not simply water moving randomly, but phenomena regulated by precise physical laws involving the atmosphere, the Earth’s rotation, and the energy coming from the Sun. In general, these movements arise from the combined action of different atmospheric agents. Furthermore, differences in temperature and salinity alter the density of water, generating movements even in the depths of the oceans. Added to this is the Earth’s rotation, which deflects water movements through the effect known as the Coriolis force. These movements allow a continuous redistribution of energy and matter across the planet. They transport heat from equatorial regions toward polar ones, influencing the global climate, and they carry nutrients that are essential for marine life. Without these movements, the oceans would be much more static environments. It can therefore be said that marine movements are not only a physical phenomenon, but also an essential element for the balance of the Earth.

INDEX

IN THIS POWER POINT WE WILL TALK ABOUT:

• Marine Waves: What They Are, Their Behavior, Characteristics, and Phenomena
• Ocean Currents: What They Are, Their Movement, Effects, and Types of Currents
• Tides;

Marine waves

Ocean currents

Tides

Wave phenomena

The bending of the waves

The refraction of waves

Marine's Waves

What they are?

Wave's element

Parameters of a wave

Behavior and characteristics

In the open sea (far from the cost)

Close to the coast

Oscillation waves are created, in which water particles perform circular waves that become smaller and smaller as they get closer to the bottom, but there is no displacement of water.

The water thickness becomes less than the crest height. The water particles are affected by the presence of the seabed, and their circular orbits deform into increasingly flattened ellipses. The wave loses energy and slows down; its lower portion is delayed compared to the upper portion.

Oscillating sea waves are difficult to model in practice, as the wind can suddenly blow in the direction of the wave, causing the crest particles to accelerate. The crest then foams downward, spilling forward.

Translational waves are created that carry the water with them. Once it reaches the coast, it will overturn, creating a beach break. Finally, there is a return effect called undertow.

Ocean currents

Movement

What they are

Effects

They are classified based on temperature differences

Cold currents

Warm currents

Mediterranean Sea

NO SPARTA!

Tides

Tides are natural phenomena that cause sea levels to rise and fall, caused primarily by the gravitational interaction between the Earth, Moon, and Sun. The Moon, despite being smaller than the Sun, has a greater tidal influence on Earth because it is closer. When the Moon attracts water, a bulge (high tide) forms on the side facing it, while a second bulge forms on the opposite side due to centrifugal force. This results in two high tides and two low tides each day. The intensity of tides varies, with spring tides (when the Earth, Moon, and Sun are aligned) producing very strong tides, and neap tides (when the Moon and Sun form a 90° angle) generating less severe tides. Geography influences tidal ranges, as is the case in the Bay of Fundy. Tides influence ecosystems, navigation, and can be harnessed to generate renewable energy.

Thank You All

Matteo Pirozzi, Pasquale Cardella, Emanuele Ignat, Marco de Mei

Warm currents

Cold currents

They move from the equator toward the poles. They have a higher temperature than the waters through which they flow

They move from high latitudes toward the equator, closing the thermal cycle. They have a lower temperature than the surrounding waters

The Movement

The movement is not straight but is deflected by:

Coriolis Force

Winds

Morphology of Ocean Basins

They can accelerate surface currents, slow them down, or reverse their course

Due to the Earth's rotation

The shape of the continents and the seafloor deflects the path of the water

It deflects the currents

whether they are

To the right in the Northern Hemisphere (clockwise)

To the left in the Southern Hemisphere (counter-clockwise)

Constant winds (trade winds or westerlies)

Periodic winds (monsoons)

Wave's Elements

A marine ona is divided into several parts with their own characteristics, namely:- Crest and venter: Respectively, the most raised and depressed parts in relation to the horizontal surface - Height: Vertical distance between crests and venters - Length: The horizontal distance between two venters or two successive crests

Mediterranean Sea

Due to more intense evaporation

The waters are saltier and therefore denser than those of the Atlantic Ocean

Deep down, saltier and denser water flows toward the Ocean

Less dense water from the Atlantic enters through the Strait of Gibraltar

What they are

Enormous masses of water that move within the oceans in a nearly constant direction and at their own speed, differing from the surrounding waters in temperature, salinity, and sometimes even color

The reflection of the waves

When sea waves strike any obstacle, they reflect, resulting in wave reflection. The reflected wave retains a lot of energy and comes into contact with another incoming wave, creating a wave surge, which consists of an oscillation in sea level a short distance from the obstacle. This usually occurs near very high coasts or near port docks. This is why, if we stand near a port, we notice that docked ships don't move, but rather undergo a small rise and fall due to the vertical movement of the wave surge.

The wave motion

The wave motion visible from land in the sea is caused primarily by wind. This creates pulsations of varying intensity, which create ripples on the sea surface, initially gentle, but gradually becoming larger and more forceful. This is because the moving air exerts a frictional force on the water, expressed as pressure, until they become forced waves. Waves can also be seen in windless areas, because the wave motion can travel long distances, thus creating free-flowing waves.

The Parametres of Wave

A wave also has some very important parameters, which are: - Speed ​​of propagation: Distance travelled, in a unit of time, by the crest expressed in kilometres per hour - The period: The time interval between two consecutive passages of a crest over the same fixed point - The direction: Horizon from which the wave appears to come

The refraction of waves

In shallow waters, however, we find a more significant phenomenon: wave refraction. This is linked to the shape of the seabed, making its effects felt when the depth (indicated by the lowercase letter p) is approximately half the wavelength (1/2 with the Greek symbol lambda). This effect causes the sea wave to move horizontally, curving, and becoming almost parallel to the coast, even though it had a different motion when further out.

Effects

They have very important effects on

and

Fishing

Climate

Cold currents, by inhibiting evaporation, promote climate aridity

Warm currents (e.g., the Gulf Stream) mitigate the climate and bring humidity and rain

Areas where cold currents flow are more productive for fishing because they are richer in nutrients