Oceans cover about 71% of the earth. They are never still. If you are looking towards the sea from land, it would look like the ocean is a stagnant place. But this is not the truth! The ocean is continuously in motion.
The oceans are great reservoirs of minerals, energy, and gases. Water can hold heat much more efficiently than air. Thus, ocean water absorbs 90% of the energy it receives.
Oceans are very complex and in-fact are less understood than the weather. The main reason why we are able to know so little about the sea is that it is more difficult to explore than land.
Ocean movements are created by the principles of physics and chemistry. There are different types of movements and these movements are influenced by temperature, density, salinity, etc. Ocean water movements are also affected by the sun, moon, and winds.
Some of the major movements of ocean water are:
- Waves
- Tides
- Ocean Currents
Key Takeaways
- Tides are long-period water level changes caused by the gravitational forces of the Moon and the Sun. In contrast, waves are the periodic movement of water particles in an oscillatory motion.
- The coastline’s geography influences tides and the depth of the water body, while the wind generates waves, and the size of the waves depends on the wind’s strength.
- Tides can be predicted accurately based on astronomical data, while wave prediction is more challenging and relies on wave height measurements, wind speed, and direction.
Tides vs Waves
The difference between Tides and Waves is that tides are the rhythmic rise and fall of the water of the ocean which is caused by the strong gravitational pull on the Earth’s surface exerted by the sun and moon. But Waves are formed because of the raging force exerted by the winds which blow over the ocean’s surface.
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Comparison Table
| Parameters of Comparison | Tides | Waves |
|---|---|---|
| Definition | Tides are the rise and fall of ocean water caused by the gravitational pull of the sun and moon | Waves are formed because of the winds blowing over the surface of the ocean |
| Location | Tides are usually seen at the deep ocean | Waves are usually seen at shallow areas of the sea |
| Formed | Tides occur because of the rise and fall of sea levels | Waves occur because of factors connected to wind and water and their interactions with each other |
| Place of occurrence | Tides happen only in oceans | Waves happen in any water body |
| Time of occurrence | Tides occur twice a day | Waves occur every time because of the movement of the wind |
| Intensity | Affected by position and location of the Sun and Moon in relation to the Earth | Affected by wind strength |
What are Tides?
Just as the Sun rises in the east and sets in the west and stars come out at night, the ocean waters will rise and fall along the shores of the water body. Tides are one such phenomenon which is the most reliable in the world.
Tides are the rise and fall of ocean water which are caused by the gravitational pull of the Sun and the Moon. This rise and fall of tides play a vital role in nature and affects maritime activities.
Tides have their origin in the oceans and proceed towards the coastline where they look like they rise and fall regularly on the surface of the sea.
The movement of the tides depends on the forces exerted by the Moon and Sun. It also depends on the position of the Sun and the Moon in relation to the ocean when the Earth is rotating on its axis.
Tides can be of two types of tides-High Tides and Low Tides. The highest part(crest) of the wave is called a high tide when it reaches a particular location and the lowest part(trough) corresponding to this is called the low tide.
A cycle of tide takes about 24 hours 50 minutes. Certain places have only one low tide and one high tide in a cycle. High tides sometimes happen before or after the Moon is in a line overhead. It occurs on a new moon day or a full moon day.
Tides are caused by the Moon’s gravitational pull which generates something called tidal force. This is because the Moon is much closer to the Earth and thus has more power to pull the tides.
The tidal force bulges out the Earth and its water to the faces closest and farthest from the Moon. Such bulges of water are called high tides.
The position of the Sun in relation to the Moon also has a role to play in causing tides. When the Sun and the Moon are in the same line, they strengthen each other’s gravitation and thus create larger tides known as spring tides.
Smaller tides are called neap tides. These happen due to the gravitational force of the Sun when it is at a right angle with the Moon.
Tides can be tracked in order to predict when a high or low tide would occur. Networks are used by nearshore water level gauges.
What are Waves?
Waves occur when the wind moves across the water surface. The friction between air and water molecules sculpts the seawater into crests transmitting energy from the wind to water thus causing waves.
When waves touch down on the shore they make a marked impact on the land by moving huge amounts of sand and shaping out rocky coastlines. Huge waves like Storm waves can move boulders above thus leaving a huge mass hundreds of feet inland.
A series of crests and troughs are formed by waves. The peaks of the waves are the crests and the low valleys are troughs. The wavelength, wave period, and wave frequency describe a wave. Water moves in a circular motion when a wave travels.
The size of surface waves is dependent on the speed of the wind, how long it blows uninterrupted, and the area over which the wind is blowing. Waves come in all shapes and sizes. Small waves are called ripples which grow less than one foot high.
Large waves happen on big expanses of water which affect the wind. These large waves are an attraction for surfers even though occasionally the waves become just too big to surf.
Some of the places famous for large waves are Waimea Bay in Hawaii, Mullaghmore Head in Ireland, etc.
Some big waves which don’t happen near the land are Rogue waves. They are formed during storms and are extremely unpredictable. They look like huge walls of water to the sailors and no one knows how and what causes these rogue waves.
Tsunami waves occur when a disturbance on the earth’s surface just like an earthquake, landslide, or volcanic eruption reaches the sea’s surface. When the tsunami reaches the shore, it slows down the contact with the bottom of the floor of the sea.
The leading part of this slowing down causes the remaining waves to pile up behind it causing an increase in the height of the wave.
Tsunami waves are only a few feet high and they travel through the deep ocean. Their speed and wavelength cause a change in the heights when they slow down at the shore.
Main Differences Between Tides and Waves
- The basic difference between Tides and Waves are in their definition itself. Tides are the rise and fall of the water on the surface of the sea influenced by the gravitational forces of the Sun, Moon, and Earth. Waves are formed by the movement of wind on the surface of the wave and the transfer of energy by the friction between the air and water molecules.
- Tides are influenced by the Sun, Moon, and the Earth whereas Waves are influenced by the action of wind on the surface of the sea.
- The intensity of Tides is based on the gravitational force of the Sun and the Moon when the Earth is rotating on its axis but the intensity of Waves depends on the speed of the wind, the duration of the wind, and the area across which the wind is blowing.
- The energy generated in Tides is kinetic energy and potential energy whereas the energy generated in Waves is kinetic energy.
- The height of Tides could range from 0-52 feet whereas the height of Waves could range from 1-30 feet.
- Waves occur almost throughout the day because of the movement of the wind whereas Tides occur mostly twice a day with a time duration of 12 hours 35 minutes.
- https://books.google.com/books?hl=en&lr=&id=41dSAAAAcAAJ&oi=fnd&pg=PA243&dq=tides+and+waves&ots=yKh4T6-LNN&sig=DrKcIvFyMiqKasuZyYQikKa7TA4
- https://royalsocietypublishing.org/doi/abs/10.1098/rsta.1971.0091
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.
