Geography and Oceanography - Chapter 17 pps

Waves in the Ocean Waves in the Ocean Words from these PPT slides are Words from these PPT slides are already on the course web site. already on the course web site. Wave Parameters Wave Parameters Properties of Ocean Waves Properties of Ocean Waves ❥ An ocean wave is an undulation of the sea An ocean wave is an undulation of the sea surface. surface. – Wave crest Wave crest – Wave trough Wave trough – Wave height Wave height – Wave length Wave length – Wave period Wave period ❥ Progressive waves Progressive waves move across the sea surface. move across the sea surface. ❥ Standing waves Standing waves oscillate about a fixed point. oscillate about a fixed point. What Causes Waves? What Causes Waves? ❥ Wind Wind ❥ Submarine disturbance Submarine disturbance ❥ Gravitational attraction of sun and Gravitational attraction of sun and moon moon Wind Generation of Waves Wind Generation of Waves ❥ Wind velocity Wind velocity ❥ Wind duration Wind duration ❥ Fetch (distance over which wind blows) Fetch (distance over which wind blows) ❥ Simply put, wave size Simply put, wave size increases increases as all as all these factors these factors increase increase . . Progressive Waves Progressive Waves ❥ Wind-generated waves are Wind-generated waves are progressive progressive waves waves because they travel across the sea because they travel across the sea surface. surface. Progressive Wave Types Progressive Wave Types ❥ Sea Sea - irregular waves in the area of - irregular waves in the area of generation generation ❥ Swell Swell - more regular waves beyond area - more regular waves beyond area of generation of generation ❥ Surf Surf - waves that have reached the coast, - waves that have reached the coast, grow in height, and break grow in height, and break Wave Motions Wave Motions ❥ Forward Forward movement of the wave form. movement of the wave form. ❥ Orbital Orbital motion of water particles motion of water particles beneath beneath the wave. the wave. ❥ It is It is wave energy wave energy , , NOT water molecules, NOT water molecules, that moves across the sea surface. that moves across the sea surface. Flow of Energy, not Mass Flow of Energy, not Mass Wave Motion with Depth Wave Motion with Depth [...]... interference - wave buildup Rogue Waves http://bit.ly/9XWFZu http://bit.ly/cs1I9b http://bit.ly/dmFsI7 Destructive Waves j Destructive wave interference - wave cancellation Progressive Wave Types j j j 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:... shallow water, the sea bottom transforms the wave’s properties This leads to wave refraction and waves collapse forming surf (breakers) Wave Refraction j Bending of the wave crest as waves enter shallow water It is due to – Drag along the bottom – Differential speed along the crest Refraction Animation Shallow-water Wave Transformations Interaction with the sea bottom j Bottom friction alters both the... Interaction with the sea bottom j Bottom friction alters both the j – Wave form Wavelength shortens (decreases) j Height increases j – Celerity (speed of wave form) j decreases Transformation of Shallow-water Waves Progressive Wave Types Sea Surf Swell Surf’s Up! Spilling Plunging, or Surging j depending on the slope of the bottom Back to Mavericks, CA Condition Black Video Motion of Water Particles . Types Progressive Wave Types ❥ Sea Sea - irregular waves in the area of - irregular waves in the area of generation generation ❥ Swell Swell - more regular waves beyond area - more regular waves beyond. generation of generation ❥ Surf Surf - waves that have reached the coast, - waves that have reached the coast, grow in height, and break grow in height, and break Wave Motions Wave Motions ❥ Forward Forward . Destructive wave interference - interference - wave wave cancellation cancellation Progressive Wave Types Progressive Wave Types ❥ Sea Sea - irregular waves in the area of - irregular waves in