While standing on a beach, you normally observe that the water is moving physically towards the shore, rolling in and out; actually, these are the water waves. The waves are formed by the movement of wind across the standing body of water on the beach creating disturbances and travelling in a circular path.
Water waves are a combination of longitudinal and transverse waves and are surface waves. The distortions propagate with the wave speed while the water molecules remain at the same positions. Most of the ocean waves are produced by wind, and the waves towards the coast pass the energy from the wind offshore. However, the energy moves towards the shore.
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What Is a Wave?
A wave can be defined as a disturbance in the form of a ridge or swell on the surface of a body of water that travels in a forward motion. The wave is an up-and-down disturbance of the water surface. Waves may be progressive, in which the crests and troughs seem to travel at a stable speed in a direction perpendicular to themselves. These waves may be standing waves in which there is no progression.
The most superficial waves recur themselves for numerous cycles and are related to simple harmonic motion.
A wave causes the water surface to move up and down in simple harmonic motion as the wave crests and troughs. The time for one complete cycle is the wave’s period T.
The wave’s frequency will be f=1/T.
The speed at which the wave disturbance moves is called the wave velocity(vw), which can also be defined as the speed with which a wave disturbance moves, and sometimes it is also termed the propagation speed or propagation velocity because the disturbance propagates from one position to another. There are several types of waves, but the most common and important ones are explained below.
Water Wave Formation
Water waves are formed by the interaction between the earth, moon and the sun. Also, the wind blowing across the surface of water bodies like rivers and oceans is the reason for the formation of water waves.
Wind waves: The most common type of waves are the wind waves, where the wind transfers a lot of energy when it comes in contact with the surface of the water, forming ripples in lakes and waves in oceans. The more substantial the wind causes, the larger the waves.
Tidal waves: Tidal waves are the wind waves that arise due to the gravitational force between the moon and the earth. The ocean water stays in its place because of the earth’s gravity, but the moon’s gravity pulls the ocean water on the planet, which causes the waves to sway up and down. This happens when the moon is closer to the side of the Earth. This is termed as high tide, and the other part of the earth where the moon is not comparable is termed low tide.
Underwater explosions: This is one more reason why waves are formed. Huge waves like tsunamis are produced due to underwater earthquakes in the oceans. Also, volcanoes, landslides, and meteors are other underwater explosions resulting in enormous destructive waves.
There are basically three types of water waves: sea waves of seismic origin (tsunamis), swell waves, and wind surges.
Water Wave Characteristics
- Wave crest and trough: The peak and bottom-most points of a wave are termed the crest and trough, respectively.
- Wave amplitude: One-half of the wave height is termed wave amplitude.
- Wave height: The vertical distance from the top of a crest to the bottom of a wave trough is called wave height.
- Wave period is simply the time break between two consecutive wave crests or troughs as they pass a fixed point.
- Wavelength: The horizontal distance between two successive crests.
- Wave speed: The rate at which a wave travels through the water; wave speed is measured in knots.
- Wave frequency: During the time interval of one second, the total number of waves passing through a given point.
What is Tsunami –
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Concept of Water Wave Tsunami
A tsunami is a phenomenon where a sequence of strong waves produces a surge in water. A tsunami is a disastrous ocean wave, generally caused by an undersea earthquake or a coastal landslide, or a volcanic eruption. Often termed tidal waves, tsunamis don’t have any connection with tides. The word tsunami is the Japanese word for “harbour wave.”
These waves discharge outward, generating impulses at speeds of up to 500 miles (800 km) per hour, reaching maximum heights of 100 feet (30 metres) near coastal areas. The primary cause of tsunamis is earthquakes on convergent tectonic plates. Global Historical Tsunami Database states that since 1900, over 80% of expected tsunamis have been produced by earthquakes.
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Frequently Asked Questions – FAQs
Can water waves travel through a vacuum?
Water waves are an example of mechanical waves, which means that they require a material medium to transmit themselves; hence, water waves cannot travel through a vacuum.
What happens to a wave as it moves into shallow water?
As the water wave enters the shallow water, two things happen: the wavelength decreases and the wave height increases.
How do water waves transfer energy?
In water waves, energy is transferred through the vibration of the water particles.
Can water waves be polarised?
No, water waves cannot be polarised because they are longitudinal waves.
Why are water waves transverse and longitudinal?
On the water surface, transverse waves are formed because of the water ripples passing on the surface.
And as we go deep inside the water body, the particles are displaced parallel to the direction in which the wave travels. Therefore, longitudinal waves are found. Hence, water waves are both transverse as well as longitudinal.
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