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Understanding Ocean Waves: Their Formation, Behavior, and Impact on Shorelines

This article explores the science of ocean waves, detailing how they transmit energy and the circular motion of water molecules. Key wave concepts such as crest, trough, wavelength, and frequency are examined. The causes of waves, including wind, landslides, volcanic eruptions, and gravitational influences from the Moon and Sun, are discussed. The dynamics of waves approaching shore, including refraction and diffraction, are explained, along with phenomena like storm surges and tsunamis. Additionally, tidal patterns, their variations, and the distinction between spring and neap tides are highlighted.

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Understanding Ocean Waves: Their Formation, Behavior, and Impact on Shorelines

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Presentation Transcript

  1. Waves Marine Science

  2. Introduction • Waves transmit energy • Water molecules move in a circular pattern • Ex: gull resting on the water, or the wave at a baseball game

  3. Wave Terms • Crest & Trough • High & low points • Height • Vertical distance between crest & trough • Wavelength • Horiz. distance between two crests • Period • Time for one full wavelength • Frequency • # of waves per second

  4. What Causes Waves? • Wind • The larger the area exposed to wind, the larger the wave • Landslides • Volcanic eruptions • Faulting / Eqs (Tsunamis) • The Moon/Sun (Tides)

  5. Interference & Rogue Waves • Interference: when two waves meet, they add to or subtract from one another • This explains wavesets • Interferences in the open ocean can result in abnormally large rogue waves

  6. Swells • Swell: formation of long wavelength surface waves • Formed by distant storms • Waves of same speed group together • Stable in their direction & frequency, free of chop

  7. Waves Approaching Shore • As waves approach shore… • Wave begins to “feel” the bottom • Circular motion of molecules becomes elliptical • Bottom of the wave slows through friction • Wave becomes too high for its length & breaks

  8. Refraction, Diffraction • Waves bend around barriers resulting in sand build-up or erosion

  9. Storm Surge • Abrupt bulge of water driven ashore by a large storm • Low atm pressure causes ocean surface to dome • Looks like a sudden, very high tide

  10. Tsunamis • Causes • EQs, landslides, volcanic eruptions • Gravity + H2O displacement make waves • Characteristics • Fast, not steep, long wavelength, approach like a wall of water

  11. Tides • Daily variations in the ocean’s level • Results of gravitational pull of the moon & sun • Create a bulge in the ocean (high tide)

  12. Tidal Patterns • Tidal patterns vary with location • Diurnal tide • Single high tide & single low tide daily • Semidiurnal tides • 2 ~ equal high & low tides daily • Mixed tides • 2 unequal high & low tides daily

  13. Tidal Patterns

  14. Spring and Neap Tides • Moon has more gravitational effect on earth than the sun • When Moon + Sun + earth are aligned, Spring tides are created • Higher than average tides • When moon is 90º to earth & sun, Neap tides are created • Lower than average tides

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