Why Do Spring Tides Occur? Understanding the Science
Can you imagine some gravitational pull of the Sun and the Moon can affect the natural world here on Earth? This phenomenon is known as a tide that occurs in the ocean. In oceans, the rise and fall of the water is a regular and common phenomenon. When these tides occur, the waves move towards the shores and affect the coastlines as well as the maritime activities of the nations. These tides are of various types. In this article, we will be talking about some of its types, such as spring and neap tides, the definition of spring tide or neap tide definition, perigean tide and all the related concepts. This topic will help you in Geography and Geology or Earth Sciences whenever you read about Oceanography.
Tides are the waves that occur through the regular change in the sea level caused by the moon and the sun. Tides emerge in the sea and go towards the coastlines. At the time of high tide, the sea is closer to the land, and at the low tide, it is farther away from, and more of the beach can be seen. It is caused by the gravitational pull of the moon and the sun. It happens twice every day. Due to the change of the tides, large quantities of water move towards or away from shore, causing tidal currents.
Spring Tide
Spring tide is one of the types of it. A tide that comes just after a new or full moon when there is a huge difference between high and low water. This is popularly known as a "King Tide" which refers to the "springing forth" of the tide during a new and full moon. It usually occurs three and four times in the year. This tide occurs at a couple of inches to normal spring tides. The term spring is derived from the concept of the tide "Springing forth". It occurs in the lunar month.
Spring Tide Definition
Some of the standard and recognised definitions are mentioned below:
"Either of the two tides that occur at or just after the new moon and full moon when the tide-generating force of the sun acts in the same direction as that of the moon, reinforcing it and causing the greatest rise and fall in tidal level. The highest spring tides (equinoctial springs) occur at the equinoxes." Or "A spring tide is an unusually high tide that happens at the time of a new moon or a full moon." - Collins dictionary.
"It is a tide of the greater-than-average range around the times of new moon and full moon." - Merriam-Webster.
Causes of Spring Tides
The various reasons why spring tides occur are mentioned below:
The forces that contribute to tides are called tidal constituents.
The moon's gravitational pull on the earth is the major tidal constituent.
The greater gravitational force between the objects is close to each other.
The sun and moon both exert gravitational force on the earth.
The moon's pull is stronger than the sun.
Because it is much closer to the earth than the sun.
It exerts a tidal force on the whole earth.
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Effects of Spring Tide
The most prominent effect of spring tide is on the tides that take place in the oceans or seas. As we have studied earlier, Spring tides occur when there is a full moon or new moon. During these events, the gravitational pull experienced by the Earth is very high because it experiences the pull from both the sun as well as from the moon. This results in the occurrence of high tides in the seas or the oceans.
Neap Tide
After the seven days of spring tide, the moon and sun are at right angles to each other. These are known as neap tides. It refers to a period of moderate tides. It has small tides. The meaning of it is that the high tides are a little lower, and the low tides are a little higher than average. It occurs because the sun and moon pull the water in different directions.
Neap Tide Definition
Some of the recognised and standard definitions are mentioned below:
"It is a tide of minimum range occurring at first and the third quarters of the moon." - Merriam-Webster.
"either of the two tides that occur at the first or last quarter of the moon when the tide-generating forces of the sun and moon oppose each other and produce the smallest rise and fall in tidal level" - Collins dictionary.
Causes of Neap Tides
The various reasons why neap tides occur are mentioned below:
When the gravitational pull of the sun is added to the gravitational pull of the moon on earth, it causes the oceans to bulge a bit more.
It occurs during the first and third quarter of the moon when the moon appears "half full."
During the time of full and the new moon, which occurs when the Earth, sun, and moon are nearly in alignment, the range of the tides is slightly larger.
This occurs twice each month.
Spring Tide and Neap Tide
The spring tides have higher high tides and lower low tides, whereas neap tides have lower high tides and higher low tides. The difference in the range of the water level between high and low tide is much larger in a spring tide than in a low tide.
Perigean Spring Tide
A Perigean tide occurs when the moon is new or full and is either closest to the Earth. The full moon or new moon closely coincides with the perigee of the moon. It often occurs six to eight times a year. These are called Perigean Spring Tides. During the time of perigean spring tide, high tides can be significantly higher than the other times of the year.
Causes of Perigean Spring Tide
The various causes of the occurrence of perigean spring tide are given below:
When the Perigean Spring Tide combines with the seasonal changes in the tide, the sea level may cause little coastal flooding in some low lying areas.
It is referred to as high tide flooding and nuisance flooding.
Main coastal flooding occurs in response to strong onshore winds barometric pressure changes from a coastal storm.
Flooding could be worse if a storm strikes during the perigean spring tide.
Sometimes Perigean Spring Tides have coincided with offshore ocean patterns and large winds that have resulted in highly coastal flooding.
Effect of the Perigee
After 28 days, the moon reaches "perigee." It is the closest point of the approach to the Earth. This is the time when the gravitational force of the moon is strong. There will be an increase in the average range of tides during these periods. After about 14 days, the moon reaches 'apogee'. This is the point where the gravitational force of the moon is weak. At this time of the period, the range of the tides decreases.
Fun Facts About Tides
Tides get affected by local conditions prevailing in the region
At many places, tidal energy is harnessed to run turbines, thereby generating energy and electricity
Tidal forces also affect solid earth, which in turn influences tides to change shape by a few inches
The first scientist to claim that tides were caused by the moon was Astronomer Seleucus of Seleucia in 150 B.C.
Tidal power is the most predictable among all other energy sources
The varying shape of the ocean floor results in larger tidal energies at some places as compared to other regions
Conclusion
To conclude, we can say that tides are very long-period waves that move through the oceans in response to the force exerted by the moon and the sun if we talk about the types of tides. They mainly are spring tides and neap tides. "Spring tides" are those tides that occurred at that time when the sun and moon both aligned with the earth. And after the seven days of spring tide, the moon and sun are at right angles to each other. At this time, moderate types of tides are produced.
These tides are known as "neap tides." Spring tides have higher high tides and lower low tides, and on the other hand, the neap tides have higher low tides and lower high tides. There is one more tide which is the type of spring tide, which is called "Perigean Spring Tide". It only occurs when the moon is new or full and either closest to the Earth. High tides can be significantly higher than the other times of the year. It is also known as the "king tide".
We have learned about tide, spring or neap tide, neap tide definition, spring tide definition and causes, and other related aspects.
FAQs on Spring Tide: Meaning, Causes and Effects
1. What is a spring tide?
A spring tide is a tide with the greatest possible difference between high and low water levels. It results in exceptionally high tides and unusually low tides. This phenomenon occurs twice each lunar month, specifically during the full moon and new moon phases when the Earth, Moon, and Sun are aligned.
2. What is the main cause of a spring tide?
A spring tide is caused by the combined gravitational forces of the Sun and the Moon when they are aligned with the Earth. This alignment, known as a syzygy, occurs during a new or full moon. The gravitational pulls of both celestial bodies reinforce each other, creating a stronger overall pull on Earth's oceans and leading to a maximal tidal range.
3. What is the primary difference between a spring tide and a neap tide?
The primary difference lies in the alignment of the Sun and Moon relative to the Earth and the resulting tidal range.
Spring Tides: Occur when the Sun, Moon, and Earth are in a straight line (full or new moon). Their gravitational forces combine, causing the highest high tides and lowest low tides.
Neap Tides: Occur when the Sun and Moon are at a right angle (90°) to each other with respect to the Earth (first and third quarter moon phases). Their gravitational forces partially counteract each other, resulting in a smaller tidal range with less extreme high and low tides.
4. Why is a tide called a "spring" tide? Is it related to the spring season?
The name "spring tide" has no connection to the spring season. The term is derived from the concept of the tide "springing forth" or "rising up." It describes how the ocean water appears to surge or spring to its highest levels during these specific lunar phases.
5. How exactly does the alignment of the Sun, Moon, and Earth create the extreme tidal range in a spring tide?
During a spring tide, the gravitational forces of the Sun and Moon work in unison. At a new moon, both are on the same side of the Earth, and their combined gravity pulls the ocean water in the same direction. At a full moon, they are on opposite sides, creating strong gravitational pulls on both sides of the planet simultaneously. This linear, combined pull exaggerates the tidal bulge, leading to the highest possible high tides and the lowest possible low tides.
6. If the Moon's gravity has a greater effect on tides, why is the Sun's role crucial for spring tides?
While the Moon's gravitational pull is the primary driver of tides due to its proximity to Earth, the Sun's gravitational force is still about 46% as strong. This is a significant force that modifies the Moon's effect. During a spring tide, this substantial force from the Sun adds to the Moon's force because they are aligned. This amplification is what turns a regular tide into an extreme spring tide. Without the Sun's contribution, tides would not have such a wide variation in their range.
7. Are all spring tides of the same height? Explain the example of a Perigean spring tide.
No, not all spring tides are of the same height. Their intensity varies based on the Moon's distance from Earth. The Moon has an elliptical orbit, and its closest point to Earth is called the perigee. A Perigean spring tide, often called a "King Tide," occurs when a spring tide (during a new or full moon) coincides with the Moon being at or near its perigee. The increased gravitational pull from the closer Moon makes these tides even higher than average spring tides.
8. How does the concept of spring tides relate to Newton's Law of Universal Gravitation from the CBSE Physics syllabus?
The concept is a direct, real-world application of Newton's Law of Universal Gravitation. This law explains that the gravitational force depends on mass and distance. Tides are caused by the differential gravitational force of the Moon and Sun across Earth's diameter. Spring tides demonstrate the principle of the superposition of forces:
When the Sun and Moon are aligned, their individual gravitational force vectors (as calculated by Newton's law) point in the same or opposite directions along a single line.
This leads to a simple addition of their effects, creating the maximum net force and thus the most extreme tides.
