Types of Tides

Types of Tides: The tides are persistent waves in the ocean. Rising and falling water levels regularly are the result of tides, which begin in the ocean and move toward the coast. Rising and falling sea levels are known as tides. Tides are a result of both the Earth and Moon orbiting each other and the combined gravitational pull of the Moon and, to a much smaller extent, the Sun.

Many variables influence tides, which in turn affect the lunitidal interval. These influences change over timescales that vary from hours to years. In this article, we will look into various types of tides in detail.

Types of Tides

What are Tides?

The rise and fall of the water level in major water bodies on Earth, such as seas and oceans, is known as a tide. This is a natural phenomenon because it is caused by the moon’s and sun’s gravitational forces. The relative positions of the sun, moon, and earth also play a role. The lunar gravitational pull is comparatively stronger because of the moon’s proximity to Earth.

The oceans that make up the earth’s surface are spread out over huge regions, and the area closest to the moon experiences the bulging of the water surface as a result of the moon’s gravitational influence. High tide results from this. Low tide results from a decrease in gravitational attraction caused by the earth’s rotation, which causes the water’s surfaces to shift about the moon. Peaks are the highest points reached by the water during high tide, and troughs are the lowest points.

Types of Tides

Many different types of tides can occur as the moon rotates around Earth, just as Earth rotates around the sun. Tides can be classified into the following:

A. Tides Based on Frequency

• Semi-Diurnal Tide
• Diurnal Tide
• Mixed Tide

B. Tides Based on the Position of Earth, Sun, and the Moon

• Spring Tide
• Neap Tide

Tides Based on Frequency

Based on frequency, tides are divided into:

Types of Tides

Semi-Diurnal Tide

This is a situation when two high tides and two low tides occur on a lunar day. Moreover, the height of peaks and the depth of troughs for both the high and low tides are the same. If we consider a high tide and a low tide combined as a tidal cycle, the semi-diurnal tide refers to two such cycles. In other words, a tidal cycle happens in each half of the day. This justifies the name ‘semi-diurnal’. In this case, the two high tides are observed at a time interval of 12 hours 25 minutes. The same applies to two low tides also. In contrast to the diurnal tide, here the time gap between a high tide and a low tide is around 6 hours 12 minutes as per the lunar day.

Diurnal Tide

This type of tide refers to a situation when any region experiences only one high tide and one low tide. The term ‘Diurnal’ indicates a daily cycle which refers to the occurrence of one high and one low tide on a lunar day cycle. So, the time interval between the high and low tide is approximately 12 hours 25 minutes.

Mixed Tide

This is almost the same as the semidiurnal tides as two high tides and two low tides occur in a lunar day cycle. But the difference is that in this case, the heights of both high tides, as well as the depth of two low tides, are not the same. This means the two high tides have different heights of peaks or highest levels, and a similar difference is observed with the lowest levels of low tides also. Therefore, this type of tide is called mixed tide.

Just like the semi-diurnal tides, it generates two high tides and two high tides in a lunar day cycle of 24 hours and 50 minutes. But the intensity or rise of tides is not equal. There may be one high tide with a higher peak followed by another high tide of lower height. Similarly, the troughs between two consecutive low tides may also be different. As per scientific explanation, the difference in height between peaks and troughs between tides is due to the inclination of the earth’s axis in relation relative to the orbital plane of the moon which influences the effect of gravitational force on the water surface.

Tides Based on the Position of Earth, Sun, and the Moon

Based on the position of earth, sun and the moon, tides are divided into:

Spring Tides

When the sun and moon align and pull the ocean’s surface in the same direction, spring tides are created. This causes low tides to drop and high tides to rise; this type of tide is known as a spring tide. It happens twice in a lunar month. It is sometimes referred to as “King Tide.”

The spring tides are unrelated to the spring season. In spring tides, the word “spring” refers to “springing forth.” These happen on days with a full or new moon.  The earth’s waters rise slightly more than usual on new moon and full moon days due to the sun’s and moon’s combined gravitational pull. “Higher” high tides and “lower” low tides are the effect of this.

Neap Tides

It takes place seven days after the spring tide. The sun and moon are at a perfect angle to one another, which is an important characteristic. The first and last quarters of the moon coincide with this tide. The resulting oceanic bulge and the gravitational attraction of the sun cancel each other out. This includes the gravitational pull of the moon. Also, during neap tides, the low tides are somewhat “higher” and the high tides are “lower” than during spring tides.

How do Tides Occur?

It is possible to understand the tides’ process by knowing the gravitational pull of the Moon and Sun. Based on their mass and distance from one another, these bodies are subject to gravitational attraction from one another. Considering that the Sun is more far from Earth than the Moon is. As a result, the moon has a stronger gravitational pull-on Earth than the Sun. So, the tide’s magnitude is determined by the moon. Although it is believed that only bodies of water are drawn toward the Earth by gravity, this is untrue.

Both land and sea masses are drawn toward one another by gravity. Gravity has a greater effect on aquatic bodies since the land has a less relative pull than water does. The relative positions of the Moon, Sun, and Earth influence the amplitude of any tide.

Effects of Tides

The following are the effects or impacts of tides:

• Because tides raise the sea level, an important part of the ocean is left vulnerable to erosion.
• It helps the tidal ports with shallow water, which makes it difficult for large ships to enter.
• A highly promising source of tidal energy, tidal currents are extensively exploited in many developed nations, including India to some degree.
• When the tide becomes very high and floods the surrounding coastal areas, it can be disastrous.
• Ecosystems like coral reefs and mangrove forests depend heavily on tides to flourish and survive.

Conclusion

Tides happen on earth at definite frequencies depending on the relative position of the earth and moon and their respective movements. Apart from these celestial bodies, the geographical features of the earth like the distribution of water bodies and landmasses also create some influence on the nature and intensity of tides.

Types of Tides UPSC Notes

Students who are preparing for UPSC can refer to this article for comprehensive notes on types of tides. Types of tides is an important topic for both UPSC prelims and mains. The UPSC syllabus covers the subject of “Tides and their types” under the geography section. For the UPSC examination, tides and their different types must be studied because they are important to understand oceanography, coastal geography, and the impact of celestial bodies on Earth’s water bodies. Students can also go through the below topics:

• Tides – Definition, Occurrence, Significance, Examples
• Importance of Tides
• Difference Between Spring Tides and Neap Tides

FAQs on Types of Tides

1. How many types of Tides are there?

Different kinds of tides can occur as the moon rotates around Earth, just as Earth rotates around the sun. Three categories of tides exist: spring and neap tides, diurnal and semidiurnal tides, and high and low tides.

2. What’s a Neap Tide?

When the sun and moon are at right angles to one another, a period of moderate tides is known as a neap tide, which occurs seven days after a spring tide. The first and last quarters of the moon coincide with this tide.

3. What is the most Common Type of tide?

Semi-Diurnal tide is the most common type of tide. Throughout a large portion of North America’s east coast, this is the most typical tidal pattern, with two highs and two lows per day with little fluctuation in the height of the subsequent high or low waters.

4. How are the different types of Tides formed?

The gravitational pull that the Sun and Moon have on Earth causes tides to form. The gravity pull of the Sun is far greater than that of the Moon, and this difference plays a significant role in the formation of tides. Based on the size and location of the Sun and Moon, there are two sorts of tides: high tides and low tides.

5. What is difference between Spring tide and Neap tide?

The larger tides that arise during the New Moon and Full Moon periods when the Sun and Moon align are known as spring tides. When we see a waxing or wanning half-moon, it indicates that the moon is not aligned with the sun. These are called neap tides, which are the lesser tides.