tailieunhanh - Geography and Oceanography - Chapter 17

An ocean wave is an undulation of the sea surface. Wave crest,Wave trough,Wave height,Wave lengt,Wave period Progressive waves move across the sea surface.,Standing waves oscillate about a fixed point. Wind velocity : Wind duration, Fetch (distance over which wind blows), Simply put, wave size increases as all these factors increase. | Waves in the Ocean Words from these PPT slides are already on the course web site. Wave Parameters Properties of Ocean Waves An ocean wave is an undulation of the sea surface. Wave crest Wave trough Wave height Wave length Wave period Progressive waves move across the sea surface. Standing waves oscillate about a fixed point. What Causes Waves? Wind Submarine disturbance Gravitational attraction of sun and moon Wind Generation of Waves Wind velocity Wind duration Fetch (distance over which wind blows) Simply put, wave size increases as all these factors increase. Progressive Waves Wind-generated waves are progressive waves because they travel across the sea surface. Progressive Wave Types Sea - irregular waves in the area of generation Swell - more regular waves beyond area of generation Surf - waves that have reached the coast, grow in height, and break Wave Motions Forward movement of the wave form. Orbital motion of water particles beneath the wave. It is wave energy, NOT water molecules, that moves across the sea surface. Flow of Energy, not Mass Wave Motion with Depth Motion Animation Deep Water Waves Waves do NOT interact with the seafloor. Orbits of the water molecules are circular. Shallow Water Waves Waves DO interact with the seafloor. Orbits of the water molecules become elliptical. Life History of Ocean Waves Life History of Ocean Waves Waves originate in the fetch area. This area is characterized by a “confused” sea state with extensive wave interference. This interference may be Constructive Destructive Rogue Waves? Constructive wave interference - wave buildup Rogue Waves Destructive Waves Destructive wave interference - wave cancellation Progressive Wave Types Sea - irregular waves in the area of generation Swell - more regular waves beyond area of generation Surf - waves that have reached the coast, grow in height, and break Transformation of Deep-water Waves: Dispersion Shallow Waves Affected by Bottom In shallow water, the sea bottom transforms the wave’s properties. This leads to wave refraction and waves collapse forming surf (breakers). Bending of the wave crest as waves enter shallow water. It is due to Drag along the bottom. Differential speed along the crest. Wave Refraction Refraction Animation Shallow-water Wave Transformations Interaction with the sea bottom. Bottom friction alters both the Wave form Wavelength shortens (decreases) Height increases Celerity (speed of wave form) decreases Transformation of Shallow-water Waves Progressive Wave Types Sea Swell Surf Surf’s Up! Spilling Plunging, or Surging depending on the slope of the bottom Back to Mavericks, CA Condition Black Video Motion of Water Particles Beneath Waves

• Địa Lý
• The Future of Ocean Observing
• Coastal Ocean
• OSU glider operations
• Oceanography
• Autonomous Underwater Gliders
• Geography
• new ocean basins
• Seafloor Spreading
• Plate Tectonics