Welcome back! Last time we discussed how waves are created out on the open ocean. This time we will focus in on how waves approach and break on the beach.

Sets:
As swell waves propagate away from their origin they form groups known as sets. Keen surfers can identify sets as they arrive. As waves get closer to shore their height increases and surfers can see the “lines” that form. Clear and organized lines are referred to as “corduroy,” after the fabric.

But how do these lines form and what causes waves to actually break on the beach?

Wave breaking:
It is important to realize that a wave is more than the crest and trough that appears on the surface of the water. Fluid particles are disturbed by wave motion beneath the surface and they move in a circular motion. Basically this means that the particles move up and down at the same rate as they move back and forth. The orbital motion of particles decreases as water depth increases.

So there is a total amount of energy associated with a propagating wave. As that wave approaches the beach it begins to “feel” the ocean floor. That is to say the deep water orbital motions of the particles become disturbed. The wave will slow down as that net energy is compressed in shallower waters. The particles will begin to move in a more oval fashion. The height of the wave continues to steepen as the water depth decreases. Also the base of the wave continues to slow down and the crest begins to outrun it. Finally when the wave face gets too steep, the base can no longer provide support and the wave breaks!

Types of breaks:
There are three main types of breaks:

Beach break – these breaks are typically what you would find at a beach. The wave breaks over a sloping sandy seafloor.

Reef break - this is where a wave breaks over a coral reef. These waves can be very beautiful and powerful but dangerous as well. Some of the most famous breaks in the world are reef breaks. The rapid change in the height of the ocean floor causes waves to arrive with a lot of energy and steepen quickly.

Point break – named after the Keanu Reeves movie! This wave breaks onto a rocky point that juts out into the water.

There are also three main ways the breaking waves travel. A wave can be either:

Left - this wave breaks from left to right from the beach perspective. It is called a left because of the surfer’s position it is breaking towards the left when their back is turned towards the wave.

Right - this wave breaks from right to left from the beach perspective.

A-Frame – this wave has shoulders on either side thus allowing multiple people to surf the same wave!

By now you probably realize how important the topography of the ocean floor is for the breaking of waves. Indeed, this is one of the most beautiful aspects of surfing. There are no two places in the world where the break is the same. In fact beach erosion and differing wind conditions causes the wave to change over time at the same place! Every wave is unique; every session offers its own challenges and joys. So next time your out in the lineup take a moment to appreciate that the wave your about to surf is the only one of its kind!

Next time we’ll discuss wind and the forecasting of surf…

Pura vida,
Nick