Key Concepts of Ocean Waves

Apr 25, 2025

Understanding Ocean Waves

Key Concepts

  • Wavelength (L): The distance between consecutive crests of a wave.
  • Wave Base: Equal to half the wavelength; depth at which the orbital motion of waves feels friction with the ocean bottom.
  • Deep Water vs Shallow Water Waves:
    • Deep Water Wave: Occurs when the wave base is less than the depth of the water.
    • Shallow Water Wave: Occurs when the wave base is greater than the depth of the water.

Example Problem

  • Given:
    • Wavelength (L) = 50 meters
    • Ocean Depth = 30 meters
    • Wave Base = 25 meters (half of wavelength)
  • Conclusion: The wave base (25 meters) is less than the ocean depth (30 meters), indicating a deep water wave.

Oceanography Wave Concepts

  • Wave Height: Vertical distance from the wave trough to the wave crest.
  • Wavelength: Horizontal distance between two consecutive wave crests.
  • Wave Period: Time between two successive wave crests.
    • Typical wave periods: 12-15 seconds in Southern California.

Graph Analysis

  • Wave Period, Wavelength, and Wave Speed Relationship:

    • Longer wave periods correlate with longer wavelengths and faster speeds.
    • Graphs can help determine wave speed and wavelength based on wave period measurements.
  • Wave Dispersion:

    • Processes by which waves separate according to speed, period, and wavelength as they travel.
    • Results in uniform ocean swells.

Wave Base and Interaction with Bottom

  • Wave Base Calculation: Depth at which waves start feeling bottom friction equals half the wavelength.
  • Changes in Shallow Water:
    • Wave velocity and wavelength decrease as waves move into shallower water.
    • Wave height increases as energy is pushed upward.
    • Wave period remains constant despite changes in velocity and wavelength.

Practical Exercise

  • Graph Interpretation:
    • Relating wind speed to wavelength formation.
    • Example: A 150-meter wavelength is formed by 42 knots wind.

Important Figures

  • Familiarize yourself with graphs showing relationships between wave attributes and wind conditions.

Additional Study

  • Review provided worksheet and lecture material.
  • Anticipate similar questions on exams concerning wave dynamics and characteristics.