What is the tidal phenomenon?

Tide phenomena, one of the most amazing and familiar natural phenomena to humans, have been closely linked to our lives for thousands of years. But do you truly understand what “tides are” and their characteristics, as well as how they form?

1. Definition of Tides

Tides are an important natural phenomenon that not only affects human life but also relates to many other issues such as earthquakes, volcanoes, and tsunamis. Understanding tides will provide humans with additional tools to respond to and harness benefits from this phenomenon.

• Tides are the phenomenon of sea or river water rising and falling alternately in a daily cycle, which can occur 2-3 times a day.
• The tidal phenomenon primarily occurs due to the gravitational forces of the Sun and the Moon acting on the Earth.
• Tides are usually periodic waves moving from the ocean towards the shore.
• When the sea level rises to its highest point, reaching the crest of the wave, it is called high tide (or rising tide).
• When the sea level is at its lowest point, at the trough of the wave, it is called low tide (or falling tide).

The tidal range is the difference between high tide and low tide. Tides help regulate sea depth and form oscillating currents, known as tidal streams.

2. What Are the Characteristics of Tides?

Stages of Tides

• When the sea level rises rapidly within a few hours and covers the intertidal zone, it is called flooding tide or high water. Sometimes, it is referred to as spring tide.
• Conversely, when the sea level quickly drops and exposes the intertidal zone, it is called ebb tide or low water.
• High tide is the moment when the water rises to its highest level, while low tide is the moment when the water drops to its lowest level.

Identifying Features of Tides

• When the sea level rises and covers areas between the sea and land, it is called flooding.
• In vast continental shelves, the tidal level will be higher.
• Tides drop to their lowest levels when they reach islands located in the open ocean.
• The flow of tidal currents is not strong in open oceans.
• Rivers’ mouths and coastal bays can affect the flow of incoming and outgoing tides.
• As the Earth rotates, the massive continents on the planet bulge out, preventing the tidal wave from moving westward.
• The water that recedes after a high tide is called ebb current.

Cycle and Frequency of Tides

• High tides have a periodic cycle that varies approximately every 12 hours and 25 minutes.
• In a day, due to the gravitational influence of the Moon and the Sun, high tides will occur three times, including two high tides and one low tide.

3. Causes of Tides

Gravitational Forces of the Moon and the Sun

• Both the Moon and the Sun generate gravitational forces acting on the Earth. The Moon’s gravitational force is stronger, accounting for two-thirds of the total gravitational force acting on the Earth, while the remaining force comes from the Sun.
• The gravitational force of the Moon causes the hydrosphere to bulge, creating an ellipse. One peak of the ellipse faces the Moon, known as the first bulge.

Centrifugal Force of the Earth

• As the Earth rotates on its axis, centrifugal force is generated and acts on the hydrosphere. This force causes the hydrosphere to bulge and create an ellipse.
• The second peak of the ellipse is opposite the first bulge, known as the second bulge.

Gravity and Tidal Forces

• Gravity is the main cause of the high tide phenomenon. The gravitational pull from the Moon and the Sun creates tidal forces, causing the sea surface to bulge nearest and farthest from the Moon.
• As the Earth rotates, tidal forces act and create tidal waves, causing the sea level to rise and fall two to three times a day.

Other Factors

• The height of the high tide also depends on other factors such as the intensity of Earth’s gravitational pull, atmospheric pressure, wind, and coastal topography.
• Additionally, when the gravitational forces of the Sun and Moon align, it creates periods of exceptionally high tides.

4. When Do Tides Peak?

The strongest tides occur when the Moon is aligned with the Sun and the Earth, creating a concentric effect between the gravitational forces of the Moon and the Sun. During this phase, either during the new moon or full moon, the combined pull of the Moon and the Sun results in a sudden increase in tides, causing the sea level to rise higher and fall lower dramatically. This makes this moment the peak of tidal activity.

5. When Do Tides Rise and Fall During the Day?

Semi-diurnal Tides

• Semi-diurnal tides are the phenomenon of sea levels rising twice a day, forming uneven tidal peaks, including high and low tides. This occurs only in equatorial regions.
• Each day will see two high tides and two low tides, spaced approximately 12 hours and 25 minutes apart.

Diurnal Tides

• Diurnal tides are similar to semi-diurnal tides, but with diurnal tides, there is only one high tide and one low tide each day, forming high and low water levels.
• The timing of high and low tides each day is approximately 24 hours apart. For example, if the tide goes out at 10 AM today, it will go out at 11 AM the next day. The same applies to high tides.

6. What Types of Tides Are There?

Red Tides

• Red tides are a phenomenon where the sea turns red, brown, or green due to excessive growth of algae and some marine bacteria.
• Impact: Toxic algae blooms cause mass deaths of marine organisms, and plants cannot survive due to lack of oxygen or polluted water. There is a high risk of food poisoning and serious illness for humans consuming contaminated seafood.
• Causes: Pollution from untreated wastewater from factories and businesses.

Black Tide

• Black tide is a phenomenon where the surface of the sea turns black due to oil spills.
• Impact: Marine environmental pollution, risk of suffocation and poisoning for marine life. Decrease in coastal tourism. Humans lose access to clean water and face the risk of consuming fish contaminated with oil, affecting health.
• Causes: Oil tanker accidents and uncontrolled oil and gas extraction activities by humans.

7. What Role Does Tidal Action Play?

Tides play a crucial role in various fields, specifically as follows:

Supporting Ecosystems

Tides help clean stagnant waters, remove toxins, and provide nutrients from the seabed to the surface, promoting the growth of underwater organisms. They facilitate the diverse distribution of fish and shrimp, building a rich ecosystem.

Marine Resource Extraction

Tides assist fishermen in catching fish and shrimp, enhancing income and stabilizing the economy. They also facilitate the extraction of other marine resources.

Climate Regulation and Land Protection

Tides reduce the risks of natural disasters such as storms and severe sea swells. They limit saltwater intrusion into inland areas, protecting river deltas.

Tourism Development

Tides create unique natural landscapes that attract tourists.

Transportation and Renewable Energy

Tides support the transportation of goods at sea and provide a renewable energy source for electricity generation.

Protection and Development of Coastal Flora and Fauna

Tides deposit fertile silt, benefiting the growth of coastal plants and animals.

8. How Do Tides Affect Human Life?

Tides not only bring benefits to humans but also have negative impacts on people’s lives and properties, detailed as follows:

Flooding and Infrastructure Damage

High tides cause flooding of roads and homes, affecting the daily lives of residents. They damage infrastructure, leading to property losses.

Environmental and Marine Life Impact

They reduce oxygen levels in the water and alter nutrient circulation rates, resulting in mass fish die-offs. Black and red tides invade land, destroying marine ecosystems and killing aquatic species.

Impact on Transportation and Vessel Safety

High tides generate strong currents and large waves, affecting vessels’ docking and fishing operations. This poses dangers for boats and fishermen.

Impact on Local Economy

Extended high tides reduce seafood harvest yields, decreasing fishermen’s incomes. Tourism revenue declines due to the effects of high tides.

9. What Are the Benefits of Monitoring Tides?

Monitoring tides offers several important benefits for humans and the environment:

Support for Transportation and Maritime Shipping

Understanding tidal cycles and forecasting tides help navigate and manage the maritime transportation industry, minimizing risks and optimizing cargo transport.

Provision of Rich Resources

Monitoring and forecasting tides provide essential information for extracting diverse resources in coastal areas, from seafood to renewable energy sources.

Conservation and Development of Coastal Ecosystems

A deeper understanding of tides aids in conserving and developing coastal ecosystems, providing food for organisms living in these areas and protecting their habitats.

Support for Research and Education

Collecting and analyzing tidal data enhances research and understanding of natural laws, providing valuable academic resources for researchers and scholars.

Assistance in Risk Management and Disaster Prevention

Monitoring tides is a crucial part of managing and mitigating disaster risks, helping to identify and warn of hazardous weather phenomena such as storms, tsunamis, and floods.

10. Conclusion

We hope that the information provided by Nệm Thuần Việt enhances your knowledge about the phenomenon of tides and how they affect our lives. The tidal phenomenon is not only an intriguing research topic but also a significant part of our daily lives. Understanding what tides are and how they form will help us leverage the benefits that tidal phenomena offer while avoiding potential risks.

• Why Do Tides Rise and Fall?
• What Is the Red Tide Phenomenon?
• Causes of Wind, Tides, and Ocean Currents