N 52° 22′ 12.778″ E 4° 53′ 42.605″
This article explains how waves are created and how the final quality of waves is created. A good knowledge of the development of waves is very important to determine where and when you can surf the best and, for example, which material is the most suitable.
The creation of waves
Waves are largely produced by wind. Storms on the open oceans cause wrinkles on the surface of the water. When these wrinkles get higher, the wind gets more grip on the wave, so the wave will grow. So the waves start small, but get higher as they approach the coast.
When waves travel across the ocean for a long period of time, they begin to form themselves into sets of waves. This means that several waves travel directly behind each other to the coast. The waves within a set arrive one after the other on the beach, with intervals until the next set arrives at the beach. Moreover, when waves approach the coast, the water becomes shallower. The water is pushed up by the wind and the wave gets higher and higher. When the wave is about to break, the bottom of the wave is slowed down by the bottom on the shore, while the top of the wave surpasses the bottom which makes the classic barrel shaped wave.
Types of swell
There are three types of swell (waves):
- Groundswell: this is the largest and most powerful swell. This swell has its origin in the situation described above. So groundswell comes from far, very far.
- Windswell: This swell is created by strong wind at a relatively short distance from the coast. This type of wind usually results in short, unstructured waves. You probably recognize this description, because these waves are often found on the Dutch coast.
- Hurricanes (tropical storm): in certain seasons the difference between the temperature of the air and of the sea is greatest, which causes tropical storms. Incredibly good waves can arise from this, which can linger for a longer period of time.
The wave height is the difference in height between the top and the valley of the wave. The height of the waves is influenced by various factors:
- Speed of the wind: the faster the speed of the wind, the greater the waves will be.
- Duration of the wind: the longer the wind blows, the higher the waves will be.
- Size of the wind: the larger the surface of the wind, the higher the waves will be.
- Temperature difference: the height of the waves is also influenced by the temperature difference between the air and the water. When the air is colder than the temperature of the ocean, the waves grow faster than when the air is warmer than the sea water. The colder the air, the higher the waves will be.
When waves are no longer influenced by wind, they gradually lose energy. The waves travel as far as they can, while losing even more energy due to natural obstacles such as islands.
In the end, waves – naturally – arrive on the beaches. The quality of the waves is in turn influenced by local conditions, which determine the final quality of the waves at the surf spots. Various factors play an important role in this. Examples are:
- Swell direction: from which side do the waves end up on the beach? Is the road “open” for the waves, or are there obstacles between the waves and the beach?
- Seafloor: when the waves hit a reef from the open ocean, large, hollow waves occur. Long, shallow ridges off the coast cause the waves to lose power. More information about this subject can be found in the article the difference between point, beach and reef breaks
- Tides: a large number of surf spots is almost entirely dependent on the tides of the ocean. For example, these spots can only be surfed at high tide or low tide. For example, some spots do not work at high tide, because the ocean is too deep. Other spots, for example, do not work at low tide, because rocks and reefs will be above water.
The role of local winds
In addition to the factors mentioned above, the final touch of the wave is provided by the wind direction at the local spot.
- Off-shore wind: when the wind blows from the land towards the ocean, it actually blows against the direction of the waves. Now the upstream is seaward and to restore balance, the underflow travels towards the beach. The waves are, as it were, “counteracted” by the opposite wind direction. This results in the best surfing conditions.
- On-shore wind: the wind blows from the ocean towards the beach. As a result, the waves are flattened and messy conditions arise. When wind comes from the sea, the surface water will be pushed ashore. To maintain the level, this water must also be drained away. This is done along the bottom. We now have to deal with an upstream to land and an underflow to sea. Messy surfing conditions arise from this situation.
- Cross-shore wind: the wind blows along the beach. This current arises when the wind blows parallel to the coast. The water along the bottom also goes in the same direction, there is no undercurrent. The water now does not have to be drained like with the sea and land wind. Messy surfing conditions also arise from this situation.
We hope that you have gained a little more knowledge about the development of waves and how the quality of the waves comes about. Do you have questions about the development of waves? Ask your question below and we will do our best to answer it.