Oceanography: Ocean Waves

Basics

  • Waves are nothing but the oscillatory movements that result in the rise and fall of the water surface.
  • Waves are a kind of horizontal movement of ocean water.
  • They are actually the energy, not the water as such, which moves across the ocean surface.
  • This energy for the waves is provided by the wind.

Parts of Waves

Wave crest and trough
  • The highest point of a wave is called the crest.
  • The lowest point of a wave is called the trough.
Wave height
  • It is the perpendicular distance from the bottom of a trough to the top of a crest of a wave.
Wave amplitude
  • It is one-half of the wave height.
Wave period
  • It is merely the time interval between two successive wave crests or troughs as they pass a fixed point.
Wavelength
  • It is the horizontal distance between two successive crests.
Wave speed
  • It is the rate at which the wave moves through the water.
  • It is measured in knots.
Frequency
  • The number of complete waves (or oscillations) that occur over a given period of time. Usually measured in cycles per second.

Wave Types

Type of Wave Period Wavelength Depth of Influence Source
Capillary or Ripple < 1 second < 2 cm Very Shallow Light wind,insects
Chop 1 – 10 seconds 1 – 10 m Shallow Strong wind
Swell 10 – 30 seconds up to 100 m Half of the wavelength  Storms
Tsunami 5 – 90 minutes 20 Km to 300+ Km To the bottom Earthquakes, Landslides, Volcanic eruptions, and more 
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