Dude, it's Physics, Part II
The Physics of Surfing (Part Two: Tubes and Barrels)
But why do some waves break as hollow grinding tubes while others crumble more gently and forgivingly? Let’s examine a little wave dynamics in order to assess the situation. Ocean waves are created by wind blowing over the ocean surface, as the kinetic energy of the air is converted into potential and kinetic energy of the water. The biggest and most powerful waves are created in massive storms. As the swells generated by these storms travel over the open ocean, the originally chaotic “victory at sea”-type wave motion is gradually organized into cleaner lines. As with all waves, it is not the actual material (water in this case) that travels any distance through the medium — it is the energy of the wave. As the wave energy passes through a point in the ocean, the water molecules rise and fall in a circular pattern but remain in the vicinity as the disturbance passes by.
Previously: Dude, It’s Physics