Wave
Overview
A wave is a water surface phenomenon generated by the frictional force of wind on the surface of seas, lakes, rivers, etc. It is a form of energy transfer, where water particles themselves remain almost in place, moving in circular orbits while only the wave form propagates. Waves significantly impact coastal erosion, ship navigation, climate regulation, and marine ecosystems.
Main Content
Generation Principle of Waves
Waves are primarily generated when wind blows across the water surface. The greater the wind speed, duration, and fetch (the distance over which the wind blows), the larger the waves become. Initially, ripples form, and as the wind continues, they grow into gravity waves. Tsunamis caused by earthquakes or submarine volcanic activity are also a type of wave.
Characteristics of Waves
Waves are described by wavelength, period, amplitude, and wave height. Wavelength is the distance between two successive crests, period is the time for one crest to pass, and wave height is the vertical difference between a crest and a trough. Deep-water waves occur where the water depth is greater than half the wavelength, while shallow-water waves near the coast have longer wavelengths and higher wave heights.
Types of Waves
- Wind wave: Directly generated by wind, irregular with short periods.
- Swell: Regular waves that propagate far after the wind subsides, with long periods and smooth profiles.
- Tsunami: Caused by submarine earthquakes, volcanoes, or landslides. Wavelengths can reach hundreds of kilometers, transforming into enormous wave heights in shallow coastal areas.
- Tidal wave: Rise and fall of sea level due to gravitational forces of the moon and sun; actually a tidal phenomenon rather than a wave.
- Internal wave: Occurs at the boundary between water layers of different densities. Not easily visible on the surface but carries significant energy.
Physical Process of Waves
Waves transmit energy but do not transport matter. Water particles move in circular orbits and return to their original positions after the wave passes. Near the coast, bottom friction causes the orbits to become elliptical, wave height increases, and eventually breaking waves occur. Breaking waves play a crucial role in coastal erosion and sedimentation.
Waves and Coastlines
Waves continuously reshape coastlines. Areas where wave energy is concentrated experience erosion, while areas where energy is dispersed experience deposition. Coastal cliffs, sea caves, and sandy beaches are all formed by wave action. Over the long term, combined with sea-level rise, this accelerates coastline retreat.
Waves and Human Activities
- Navigation: High waves threaten ship safety, and wave prediction is essential for route planning.
- Ocean Energy: Wave energy conversion to electricity is under research and commercialization.
- Leisure: Marine sports such as surfing, yachting, and kayaking heavily depend on wave conditions.
- Climate: Waves facilitate heat and gas exchange between the ocean and atmosphere, influencing the climate system.
Latest Trends
As of 2024-2025, global average wave height is on the rise due to climate change. The frequency of extreme waves is increasing, particularly in the Southern Ocean and the North Atlantic. Satellite-based wave observation technology has advanced, improving the accuracy of real-time wave prediction models, and AI-based wave pattern analysis research is active. In the field of wave energy, demonstration-stage projects are underway in South Korea, the UK, Australia, and others, with the first commercial wave power plant expected to begin operation in 2025. Additionally, nature-based solutions such as artificial reefs and beach restoration projects are expanding to prevent coastal erosion.
Related Topics
- [[Ocean current]]
- [[Tide]]
- [[Coastal erosion]]
- [[Tsunami]]
- [[Wave power]]
- [[Climate change]]
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