deep water away from the wind field, which generated the waves
● their direction of propagation is thus not necessarily the same as the local wind direction
● wavelengths of on average 100 km
● surge waves and rogues: aka, storm waves can be generated during extreme weather conditions (hurricanes, cyclones, etc) when swells travelling in different directions form interference patterns
What are breaking waves?
The idea of waves being energy movement rather than water movement makes sense in the open ocean, but what about on the coast, where waves are clearly seen crashing dramatically onto shore?
When waves approach the shore, their profile is modified by friction (resistance) with the sloping sea floor. The seafloor obstructs and slows the motion of the trough of the wave, while the crest continues to move at its usual speed. The motion of the water underlying the wave consequently becomes more elliptical than orbital. As a result, the wave begins to lean forward as it approaches the shore. Eventually, the fast-moving crest outruns the slow-moving trough, and spills over the front of it - i.e, collapses or breaks.
Tsunamis
A tsunami (from the Japanese: tsu, ‘harbour,’ and nami, ‘wave’) is a very long wave of seismic origin. It is generated by the displacement of a large volume of water. More than 80% result from large scale underwater earthquakes. The rest are generated by underwater landslides, volcanic eruptions, and even meteorite collisions.
Unlike wind-driven waves, which only travel through the topmost layer of the ocean, tsunamis move through the entire water column, from the ocean floor to the ocean surface.
A classic tsunami wave occurs when the tectonic plates beneath the ocean slip during an earthquake. The physical shift of the plates force water up and above the average sea level by a few meters.This then gets transferred into horizontal energy across the ocean’s surface.