Besides the usual waves and currents, there is another kind of movement on the sea floor and that is known as sea tide. Here reason, types and influence of tide given below.
Reason of sea tides
The main reasons are the attraction of the Moon and Sun on the Earth, and the centrifugal force caused by the Earth’s rotation. Although the Moon is much smaller than the Earth, its proximity has a stronger attraction to the Earth. Therefore, the part of the Earth that faces the Moon as it orbits is the most affected by gravity. The terrain is hard and there is no effect of that attraction. However, it causes the waters of the sea to rise.
Primary sea tide
whenever the sea encounter or faces the moon, tides are created. Because moon has stronger attraction to the sea at that time. This is called the Primary sea tide.These tides occur in a predictable pattern, usually with two high tides and two low tides each day, though this phenomenon can vary or different on the basis of locational diversity.
Secondary tea tide
Due to the attraction of the Moon, at the time of primary tide, another tide occurs in the exact opposite direction. However, the distance from the Moon is less than the effect of gravity. The water is flooded mainly by the centrifugal force caused by the Earth’s rotation. This tide is called the Secondary Tide.
Spring sea tide
On full moons and new moons, the Moon, Earth, and Sun fall almost in the same line. These two days the tides rise higher due to the attraction of both the Moon and the Sun. This is called Spring sea tide.
Neap sea tide
On the seventh and eighth days after full moon, the Earth, Moon and Sun are at right angles and tide is less strong. The difference of high tide and low tide is very minimum. This tide is called a neap sea tide.
Diurnal sea tide
In diurnal sea tide, one high tide and one low tide occurs. Or in simple words, it’s a phenomena of occurring one big high tide and one small low tide.
Semi diurnal sea tide
Semi diurnal sea tide is a phenomena where two high tide and two low tide occurs. In semi diurnal sea tide, the height and depth of both tides are equal.
Mixed sea tide
In mixed sea tide, two high tide and two low tide occurs but the height and depth of both the tides are not same. A mixed sea tide means a tidal pattern that has characteristics of both semi-diurnal and diurnal tides. In other words, there are two high tides and two low tides, but they are not equal in height. The two high tides and the two low tides occur within a 24-hour period, but the timing and height of the tides different.
Influence of tide
Tidal influences are observed in coastal and estuarine areas. The tides wash away the sediment accumulated in the estuary, facilitating the navigation of boats and ships. Ships can easily navigate to ports located in shallow coastal or estuarine areas due to flooding during high tide. Fish are abundant in tidal estuaries. Sea tides have another importance is about maintaining Balanced ecosystem. Sea tides are beneficial for various plants and other creatures living in the sea. Somehow pollution can also be controlled with the help of sea tides. Various countries have also generated electricity from tidal energy.
Tides basically occur by the gravitational pull of the Moon on the Earth’s oceans. The Moon’s gravity attracts the water on Earth toward it. It creates a wave of water on the side of the Earth facing the Moon. This is termed as the direct tide or high tide. At the same time, on the opposite side of Earth, a second wave occurs, also creating a high tide. This second wave is because of the centrifugal force caused by the rotation of earth and moon. The water is effectively “left behind”. It is due to the earth and the moon rotate around a common center of mass.
The Moon has the strongest effect on tides. In the same way the Sun also has a gravitational pull on Earth’s oceans and seas. But the Sun is so far away from Earth compared to the Moon, so its gravitational force is weaker as compared to the moon. It is due to distance being greater from the sun to earth as compared to distance between moon and earth. When the Sun, Moon, and Earth are aligned, the gravitational forces of the Sun and Moon combine to produce spring tides than normal high tides and lower than normal low tides.
When the Sun and Moon are at right angles to each other, their gravitational forces partially cancel out, leading to neap tides lower high tides and higher low tides than usual.Tides typically follow a semidiurnal pattern. Which means there are two high tides and two low tides each day. This cycle is roughly 12 hours and 25 minutes long, which is the time it takes for a given location on Earth to move through both high tides and low tides. The difference in the timing of high and low tides is due to the Moon’s orbit around Earth. While the Moon and Sun are the primary influencer, several other factors can affect the tides in a particular location.
Narrow bays can change tidal ranges, causing very high tides, while wide open beaches tend to have less tides in the form of its frequency. The Earth’s orbit around the Sun is slightly elliptical, meaning the gravitational attraction from the Sun is slightly stronger when Earth is closer and weaker when it’s farther away. Similarly, the tilt of Earth’s axis can influence the timing of tides throughout the year. Underwater topography such as ocean basins, continental shelves, and the slope of the shoreline can affect the height and timing of tides. Shallow waters may experience huge tidal fluctuations. In due course of time, tidal interactions between the Earth and the Moon cause tidal friction. This friction gradually slows the Earth’s rotation and causes the Moon to slowly drift away from Earth. This effect is happening very slowly.
I have given simple and basic explanation of sea tides. Hoping that students will read and understand properly.
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