What is the tidal phenomenon?

The phenomenon of tides, one of the most magical and familiar natural phenomena to humans, has been associated with our lives for thousands of years. But do you really understand 'what is a tide' and its characteristics, as well as how it is formed?

Things to know about tides

1. Definition of tide

Tides are an important natural phenomenon that not only affects human life but is also related to many other issues such as earthquakes, volcanoes or tsunamis. Understanding the knowledge of tides will help people have more tools to cope with and take advantage of this phenomenon.

1. Tides are the phenomenon of sea or river water rising and falling alternately in a daily cycle, possibly 2-3 times per day.
2. Tides are caused mainly by the gravitational pull of the Sun and Moon on the Earth.
3. Tides are typically periodic waves that move from the ocean toward the shore.
4. When the sea level rises to its highest point, reaching the crest of the wave, it is called high tide (or spring tide).
5. When the sea level is at its lowest, at the bottom of the wave, it is called low tide (or ebb tide).

Tidal amplitude is the difference between high and low tide levels. Tides contribute to the adjustment of the depth of the sea and form oscillating currents, called tidal currents.

2. What are the characteristics of tides?

Phase of the tide

1. When the sea level rises rapidly over a few hours and covers the intertidal zone, it is called a flood tide or tidal inundation. It is also sometimes called a high tide.
2. Conversely, when the sea level drops rapidly and the intertidal zone is exposed, it is called ebb tide or low tide.
3. High tide or spring tide is the time when the water level is highest, and low tide is the time when the water level is lowest.

Identifying characteristics of tides

1. When the sea level rises and covers the areas where the sea meets the land, we call it tidal flooding.
2. On large and bulging continental shelves, high tides will be higher.
3. The tides are lowest when they reach islands located in the ocean.
4. Tidal currents are not strong in the open ocean.
5. Estuaries and coastal bays can influence the flow of the tides.
6. As the Earth rotates, the planet's giant continents bulge outward, preventing the tide from moving westward.
7. The water that recedes after a high tide is called ebb tide.

Tidal cycle and frequency

1. Spring tides have a periodic cycle of change in time ranging from once every 12 hours and 25 minutes.
2. During a day, due to the influence of the Moon and the Sun, high tides will appear three times, including two highest times and one lowest time.

3. Causes of tides

Gravitational force of the Moon and the Sun

1. The Moon and the Sun both exert a gravitational force on the Earth. The Moon's gravitational force is stronger, accounting for 2/3 of the total gravitational force on the Earth, the rest is from the Sun.
2. The Moon's gravity pulls the hydrosphere upward, forming an ellipse. One vertex of the ellipse lies directly opposite the Moon, and is called the first large water region.

Centrifugal force of the Earth

1. As the Earth rotates around its axis, centrifugal force is generated and acts on the hydrosphere. This force causes the hydrosphere to also bulge and form an elliptical shape.
2. The second vertex of the ellipse lies opposite the first large water region, called the second large water region.

Gravity and tidal forces

1. Gravity is the main cause of tides. The gravitational pull of the Moon and the Sun creates tidal forces, causing the ocean surface to bulge on the sides closest to and farthest from the Moon.
2. As the Earth rotates, tidal forces act and create tidal waves, causing ocean water to rise and fall two to three times a day.

Other factors

1. The height of high tides also depends on other factors such as the strength of the Earth's gravity, atmospheric pressure, wind, and the characteristics of the coastal terrain.
2. In addition, when the gravitational pull between the Sun and the Moon coincides, it will create high tides.

4. When is the tide strongest?

The strongest tides occur when the Moon is aligned with the Sun and Earth , creating a concentric effect between the gravitational forces of the Moon and the Sun. During this phase, when the moon is new or full, the gravitational forces of the Moon and the Sun combine to create a sudden increase in tides, causing the ocean water to rise and fall dramatically. This makes this time the time of the strongest tides.

5. What time of day does the tide go in and out?

Semi-diurnal tide

1. Semi-diurnal tides are the phenomenon of sea level rising twice in one day, creating uneven tidal peaks, including high high water levels and low high water levels. This only occurs in equatorial regions.
2. There are two high tides and two low tides every day, about 12 hours and 25 minutes apart.

Japanese tide

1. Diurnal tide is also a type of tide similar to semi-diurnal tide, but with diurnal tide, each day there is only 1 high tide and 1 low tide, creating high ebb tide and low ebb tide.
2. The times of high tide and low tide are about 24 hours apart each day. For example, if low tide is at 10am today, then tomorrow it will be low at 11am. The same goes for high tide.

6. How many types of tides are there?

Red tide

1. Red tide is a phenomenon in which the sea turns red, brown or green due to the overgrowth of algae and certain marine bacteria.
2. Impact: Toxic algae blooms kill a large number of marine life, plants cannot survive due to lack of oxygen or polluted water. The risk of food poisoning and serious illness for humans is high when eating contaminated seafood.
3. Cause: Water source is polluted from untreated wastewater from factories and enterprises.

Black Tide

1. Black tide is a phenomenon in which the sea surface turns black due to oil spills.
2. Impact: Marine pollution, risk of suffocation and poisoning for marine life. Decreased marine tourism. People lose clean water sources and are at risk of eating fish contaminated with oil, affecting their health.
3. Cause: Oil tanker sinking and uncontrolled human oil and gas exploitation.

7. What role do tides play?

Tides play an important role in many different fields, specifically as follows:

Ecosystem Support

Clean stagnant ponds, remove toxins. Provide nutrients from the seabed to the water surface, helping aquatic organisms develop. Create conditions for diverse distribution of fish and shrimp, building a rich ecosystem.

Exploitation of marine resources

Support fishermen in catching fish and shrimp, increase income and stabilize the economy. Facilitate the exploitation of other marine resources.

Climate regulation and land protection

Minimize the risk of natural disasters such as storms and fierce waves. Limit the intrusion of salt water into the mainland, protect river deltas.

Tourism development

Create unique natural landscapes to attract tourists.

Transport and renewable energy

Support shipping of goods by sea. Provide renewable energy sources in electricity production.

Protection and development of coastal flora and fauna

Depositing fertile alluvium for coastal plants and animals to grow well.

8. How do tides affect human life?

Tides not only bring benefits to people, but also cause negative impacts on people's lives and properties, specifically as follows:

Flooding and infrastructure destruction

High tides cause flooding of roads and houses, affecting people's lives and activities. They destroy road infrastructure and houses, causing property damage.

Impact on the environment and marine life

Reduced oxygen levels in water, changing nutrient circulation rates, leading to mass fish deaths. Black and red tides invade the mainland, destroying marine ecosystems and killing aquatic life.

Impact on traffic and safety of vessels

High tides bring strong currents and big waves, affecting boats docking and fishing at sea. Dangerous for boats and fishermen.

Impact on local economy

When high tides last long, seafood harvests decrease, reducing fishermen's income. Tourism revenue decreases due to the impact of high tides.

9. What are the benefits of monitoring tides?

Tide monitoring has several important benefits for people and the environment:

Maritime transport and traffic support

Tide cycle determination and forecasting helps navigate and manage the maritime transport industry, minimize risks and optimize the movement of goods.

Provide rich resources

Tidal monitoring and forecasting provide vital information for exploiting diverse coastal resources, from fisheries to renewable energy sources.

Conservation and development of coastal ecosystems

Understanding tides helps preserve and develop coastal ecosystems, from providing food for the creatures that live in these areas to protecting their habitats.

For research and education

Collecting and analyzing tidal data helps to deepen research and understanding of natural laws, and provides a valuable academic resource for researchers and scholars.

Support in disaster risk management and prevention

Tide monitoring is an important part of disaster risk management and prevention, helping to identify and warn of dangerous weather phenomena such as storms, tsunamis, and floods.

10. Summary

Hopefully, with the information provided by Nem Thuan Viet, you have gained more useful knowledge about the tidal phenomenon and how it affects our lives. The tidal phenomenon is not only a fascinating research topic but also an important part of our daily lives. Understanding what the tide is and how it is formed will help us know how to take advantage of the benefits that the tidal phenomenon brings, while avoiding possible risks.