Introduction
The moon and the sun attract the water body and land of the earth’s surface. As a result, the water body of the earth’s surface rises and falls in one place every day at regular intervals. This phenomenon is known as the tide. There are various types of tides. Below is a discussion of different types of tides and their differences (1) & (3).
Tide is a rhythmic rise and fall of seawater in the same place regularly by the attraction of the moon and the sun. High tides and low tides occur twice a day.
The intensity of tides is not the same in all parts of the ocean throughout the year. The attraction of the sun is also largely responsible for the tides. However, being far away, the attraction of the sun is less effective than the attraction of the moon (2).
Definition of tide
There is another motion in the oceans besides ocean currents and ocean waves. Due to the gravitational pull of the moon and the relatively low gravitational pull of the sun, the seawater swells in one place on a regular basis twice a day and then recedes in another.
This regular swelling of the ocean water due to the attraction of the moon and the sun is called high tide and this regular lowering of the ocean water or low tide is called low tide.
So as a definition of the tide we can say, tides are the rise and fall of ocean water due to the gravitational forces of the sun and the moon (4).
Cause of tide
The causes of the tides are
1. The gravitational force exerted on Earth by the Sun
2. Gravitational force exerted on Earth by the Moon
3. Rotation of the Earth (1).
Types of tides
Tides Based on the Position of Earth, Sun, and the Moon
1. Spring Tides
2. Neap Tides.
Tides Based on Frequency
1. Semi-Diurnal Tides
2. Diurnal Tides
3. Mixed Tides.
Definitions of the different types of tides
1. Spring Tides
- When the sun and the moon are in a straight line with each other and pull the ocean surface in the same direction, then Spring tides are caused.
- In a lunar month, it occurs twice.
- It is also known by the name of ‘King Tide.’
- A Spring tide occurs on a full moon or new moon days.
- In spring tides, the difference between high tides and low tides is greatest.
- Spring Tides are the result of the sun and moon working together to exert more pull on the earth’s oceans.
2. Neap Tides
- When the sun and the moon are at a right angle with respect to the earth, Neap tides or low tides are caused.
- It occurs seven days after the spring tide.
- Neap Tides occur on quarter moon days.
- In Neap Tides, the difference between high tides and low tides is the least.
- Neap tides are the result of the moon and Sun working against each other.
According to the frequency definition of tides
1. Semi-Diurnal Tides
A semi-diurnal tide consists of two phases of equal high water and two phases of low equal water per day. When the moon is directly above the equator, there is a tendency for semi-diurnal tides. Semi-Diurnal tides are found along the Atlantic coast of the United States.
2. Diurnal Tides
Diurnal tide consists of one phase of high water and one phase of low water per day. This tide occurs when the moon is farthest from the equator. These tides occur daily on the coast of the Gulf of Mexico.
3. Mixed Tides
Mixed tides are like semi-diurnal tides. There are two phases of high water and two phases of low water every day. Mixed tides occur when the moon is too far north or too far south of the equator (2) & (5).
Difference between Spring Tides and Neap Tides
In addition to ocean currents and waves, there is a natural movement of water in different oceans of the world. As a result, the water swells in one part of the ocean for a short period of time and then goes down in another part. In this way, the water level fluctuates once every 12 and a half hours. This is known as the tide. There are different types of tides. One of the spring and neap tide. Below is a discussion of the differences between spring and neap tide.
Spring tide |
Neap tide |
| 1. When the moon, the earth, and the sun are in the same straight line, the combined attraction of the moon and the sun acts in the same place on the earth, resulting in a spring tide. | When the moon, the earth, and the sun are at right angles, the attraction of the moon and the sun on the earth is opposite to each other, resulting in the neap tide. |
| 2. The influence of spring tide on human life is greater than the neap tide. | The effects of neap tide on human life are less. |
| 3. Spring tide occurs on the date of the new moon or full moon. | Neap tide occurs on the date of the first and third quarter moon days. |
| 4. In this case of spring tide, sea and ocean water is the most swollen. | In the case of a neap tide, the swelling of the sea and ocean water is less. |
| 5. On the date of the new moon, the moon and the sun are in the same straight line on the same side of the earth. And on the date of the full moon, the earth is in the same straight line between the sun and the moon. | On the date of bright fortnight and dark fortnight, the sun and the moon are perpendicular to the earth. |
| 6. These types of tides are strong tides. Because it is created by the combined attraction of the moon and the sun. | A neap tide is a weak tide (1) & (2). |
Similarities
1. Spring and neap tide both occur in the combined attraction of the moon and the sun’s gravitational force.
2. In both cases the sea level rises.
3. Neap tide and spring tide both occur twice a month (2).
Q&A
1. What are the four types of tides?
Based on the position of Earth, Sun, and the Moon the four types of tides are-
- Primary tide
- secondary tide
- Spring tide
- Neap tide.
According to the frequency of tides, there are also four types of tides. These are-
- Semi-Diurnal Tides
- Diurnal Tides
- Mixed Tides
- Meteorological tide (2).
2. What are spring tides and neap tides?
- Spring tide
When the earth, moon, and sun are in the same straight line on the date of the new moon and full moon, the strong tide created by the combined gravitational force of the moon and the sun is called a spring tide.
- Neap tide
On the dark and bright fortnight, the sun and the moon are at right angles to each other. As a result, the moon and the sun attract the earth from opposite directions. The resulting low tide is called the neap tide (2).
Written By: Manisha Bharati
