What’s in a wave?

Imagine looking out at sea,  waiting for that moment, a split second where instinct kicks in and says ‘GO’, tunnel vision on the patch of blue that’s gargling into adolescence and then catching it as it grows into adulthood.  You can’t tame it, with instinct and your surfboard you’re looking to own it at the expense of it possibly engulfing you; you do this with instinct and your surfboard.

It seems that good surfers have a keen eye for spotting where and when the perfect wave will break. The surfer uses their instinct to see the future of the landscape, but what is it that creates that perfect wave? 

The surfer’s perspective
Sat out upon the rolling sea, from the surfer’s perspective, the landscape at that point is an endless blue littered with the froth created by the wind chopping up the surface of water – these are called white-caps.
The whitecaps can form crests giving the wind more surface area to work with, creating a peak. Those small peaks start moving away from the wind, expending a bit of its energy by turning its choppiness into a nice rounded wave, which is called a swell. 
At this point it seems pretty weak and unassuming, as all that energy is underwater. This energy becomes apparent when the waves get closer to the shore and starts making contact with the land underneath. As the wave begins encroaching upon the land the wave’s energy is forced upward above the water surface, the front of the wave slows before the back of the wave causing to break; here we have the rideable wave.
The shape of the land beneath the water has a say in how the wave turns out; if the land is steep the wave will crash creating a barrel wave, if the slope of the land is more gradual then the wave will break slowly forming a ‘crumbling’ wave. 
 Barrel wave                                                                                        Crumbling wave
Img source (right): quiksilver.com/eddie
The physics of the wave
The waves make their way onto the shore in rows; sometimes the ones behind can catch up with the wave in front and add together creating a super wave. This is simply constructive interference.
If you picture the wave from the side you can see it as a series of orbital waves. This motion is a flow of energy from peak to the trough and back round again, making what is basically a large circle. When it comes into contact with the land this circular motion is forced upwards, essentially squishing it and disrupting the circular flow of the water, which causes the wave to break.
We know what creates the ideal wave and now we have the technology to actually make an artificial one. Professional surfer, Kelly Slater, rode an artificial wave in 2015. After years of research it was discovered that the best way to simulate barrel waves in the ocean was to use the wind (pneumatics). This was the wave that Kelly Slater surfed. 
By simulating ocean swells we can replicate an experience that is closely comparable to ocean surfing. Engineers have designed hundreds of wave pools for water parks, but the technology incorporated to make surfing waves today is a quantum leap in the evolution of surf pool technology. 
In the right conditions the water flowing back to the sea can form a rip current. This is the term for the water that’s moving from the shore back to the sea; the current can drag swimmers into the open water at a speed that’s too difficult to swim against. 
The weather can also change the intensity of the wave. For instance strong winds and pressure from a hurricane can create a series of waves that are formed in deep water, which intensify as they approach land.
The land at the bottom of the water can also massively affect the wave; Tsunamis for instance, are due to the land under the water shifting – different to tides which are created on the surface by wind and the magnetic force from the moon and sun. Tsunamis are caused by the energy beneath the surface; a volcanic eruption, submarine landslide or an earthquake can cause this huge surge of energy underwater that eventually makes its way onto the surface as it comes closer to the shore. 
Whilst the physics perspective is equally as stunning as the surfer’s, encouraging a safer perspective on the waves, nothing jars the surfer’s instinct; that wave is theirs for the taking and admittedly, it’s infectious… Let’s go surfing.