#8 Your best surf trip

One of my earliest memories is sailing in an optimist on the Markermeer. Sailing when I was barely able to walk made me familiar with water at a very young age, but it was only during my teenage summer holidays in France that I really got passionate about the ocean. When a surf instructor stabbed my inflatable bodyboard - apparently they are super dangerous in the event of strong currents -  I suddenly had a solid argument to convince my mother to rent a real surfboard for me. She could not resist and hence my passion for the ocean and its waves was born.

Over the years surfing became an increasingly dominant element of my life. Although it sometimes feels frustrating to have your life controlled by such an irrelevant thing as riding waves, it has brought me so much. Surfing made me travel the world, meet many friends and made me feel more connected to marine environments and their current environmental issues. It was also the leitmotiv to study oceanography. However, most importantly, it has allowed me to feel at peace; when you walk into the ocean, and start to paddle out, it feels like the waves wash your daily hassles away.   

Surfing is a weird sport; most of the time you spend getting to the beach, where you still have to find the right break. Then, when you are in the water, you still have to paddle so much that many people don’t understand why you would do it. Compared to all hours you spend traveling and paddling, the time you actually stand up on a wave is nil. Nevertheless, there is something that makes so many surfers come back to the beach all the time – even in the Netherlands, where waves and weather conditions are not ideal to put it mildly. So why do all these people surf? If people take so much effort it must be a truly epic experience - and I actually think it is. I think that I’m addicted to surfing due to its unique mixture of being in a meditative state, while having a sudden shot of adrenaline. When you are surfing, you are not thinking: you paddle on pure intuition from here to there, and completely lose track of time. All surfers know how difficult it is to estimate how long you have been surfing. Then, when you finally paddle in for a wave, there is this shot of adrenaline and the sensation of pure enjoyment; it’s just you and the wave – freedom – and it remains fun and challenging because every wave is different.

So where do the waves we surf come from? Let me take you on a journey along the European continental coast to understand why and where we can surf, and at what time of the year.

In oceanography there is a fundamental distinction between swell and seas: swells are groups of waves that have travelled out of the region where they are being formed, while wind waves are waves that are still actively being forced by wind. All waves we surf are created by wind, but we speak about swell when waves travel out of their region of origin. Just imagine a storm somewhere near Ireland. If you’re unfortunate, and sailing that area, you would experience rough seas full of wind waves. If you’re lucky however, and find yourself in France, you may find the swell, developed from these wind waves, a few days later upon your coast. Wind waves are only the raw material that swells are made of, and the more energy wind waves accumulate while being driven by wind, the greater the likely-hood they will transform into a swell. Wind waves develop into swell as they move away from the storm; gradually, the choppy components dissipate, leaving only the pure traveling energy of the swell. Swells that have more energy move faster than those with less energy. Over long distances, more energetic swells, because they are moving faster, eventually over take and pass slower, less energetic swells. And swells that don't have enough energy, eventually die. To summarize, here in the Netherlands we are unlucky: we mostly have wind waves, and, occasionally, an energetically poor swell coming from the north.

As I said, all waves we surf are generated by wind: wind waves in the Netherlands from storms relatively close to, or even on, the coast; while swells in France originate from storms (which practically means a lot of wind) somewhere far away over the North Atlantic ocean. But how come all these waves differ from eachother? There are three important factors which determine size, period and energy of waves. The size is in the first place dependent on wind speed, but here there is an interesting relationship. The amount of energy which is transmitted from the atmosphere into the ocean does not increase equally with wind velocity; the relationship is non-linear. When wind velocity increases by a factor of two, the amount of energy transmitted into the ocean will increase by more than a factor of two. Secondly, wave height is dependent on the area over which the wind blows: the larger the area, the more energy will be transmitted into the ocean. This area over which the wind blows is called the fetch. Thirdly, the size of the waves is dependent on the duration of a storm. The longer a storm takes place, the more energy will be transmitted into the ocean. Just a brief strong gust will effectively not result in powerful waves, while a more gentle, but long lasting wind may generate some powerful swell. So, to generate powerful and large waves, you really need a mix of these factors: stormy conditions, lasting for some days over a relatively large area. The biggest waves are generated with a traveling fetch. This is when a storm travels in the same direction as the waves, continuously transmitting energy into the ocean. This typically happens over the North Atlantic ocean during European winter, where storms often track, like the swells, from Greenland to Ireland. This is one of the reasons why you can find several big waves on the western European coast, while the east coast of the United States is not known for big wave surfing.

Since waves we surf are being generated by winds, they are essentially an effect of large scale climate patterns that dictate the atmosphere over the ocean. Earth’s climate is a sun driven system. Globally, over the period of one year, Earth’s surface receives about 240 watt of solar power per square meter. However, the sun’s heat is not evenly distributed across the surface. Earth is a sphere so light comes in at an angle towards the poles, and hence the equator receives more solar energy than the higher latitudes. This meridional (North-South) energy imbalance is constantly being redistributed (or evened out) by the atmosphere and the ocean, together known as Earth’s heat engine. The redistribution happens on several timescales; whereas water parcels take several years to travel the gulf stream, wind can cover vast distances in just a matter of days. The ocean and the atmosphere are in constant interaction, but where the ocean drives the atmosphere on the longer time scale, the atmosphere drives the ocean on the shorter time scale. When cold polar air travels towards the lower latitudes it collides with warmer subtropical air in the mid-latitudes. This collision results in frontal precipitation and low pressure cyclonic storm systems. The typical low-pressure system that we have over the North Atlantic Ocean is called the Icelandic low. It is a semi-permanent centre of low atmospheric pressure between Iceland and southern Greenland. This climate feature becomes more developed in winter. When we gradually approach the dark days of December, the heat imbalance between the equator and the north pole becomes more profound. Due to fundamental differences in heat capacity between land and water, a complex atmospheric flow (jet stream) will develop and fixate this low-pressure system around Iceland, while forcing a high-pressure system around the Azores.

 This entire system of fronts, subtropical highs, and tropical rain migrates with the seasons, moving northward during the Northern Hemisphere summer and southward during the Northern Hemisphere winter. Although this Icelandic low-pressure system is definitely more intense in winter, it will still generate some waves further up north in summer. Therefore you still may find some waves in northwest Ireland in European summer, while continental Europe is more likely to be sheltered by that same island.

By the end of summer, the Icelandic low becomes more defined (surface pressure deepens; the pressure drops) and starts migrating towards the equator. Practically this means waves for all of continental Europe, but the most favourable conditions during early autumn will be found in France. In this period, the Icelandic low starts to be more persistent, constantly generating medium sized swells, while water is still warm along the French coast. Obviously this is nice because we love to surf in warm water, but more importantly it also generates a favourable wind system. Due to the earlier mentioned difference in heat capacity of land and water, land will lose and gain its heat more quickly than water. In early autumn, the ocean will by night and early morning be relatively warm compared to land. Therefore air will rise above the ocean, effectively creating a gentle pressure gradient between land and ocean in the coastal zone. Here, rising air above the ocean will have to be replaced with air coming from land; your early morning offshore sea breeze.

While days become shorter, the Icelandic low will deepen further, increasingly generating powerful long-period swells, which travel all way from Greenland to Europe. Generally Dutch people – only being used to low-period waves – consider longer periods only as a good thing. In France however, they know that longer periods can also be the limiting factor. Waves will travel faster (dispersive character of waves) and extend deeper into the ocean as their period grows. Here just image that waves have a sinusoidal shape; they also extend into the ocean. Ultimately waves start to break when they cannot sustain themselves due to the friction of the bottom; they break because they feel the bottom. Usually when waves with, let’s say a period of greater than 14 seconds, approach a sandy shore, the sandbars will not be big enough to make the waves gradually crumble down; due to the high period, which also means more energy, the wave will break at once. They close out we say, and this is not good for surfing. So as the swells gradually become more powerful during winter, characterized by higher periods, surfing in France becomes more tricky because the sandbars are not able to handle the powerful swells anymore.

Luckily this is just when Spain and Portugal start to fire up. Spain and Portugal are excellent places to be in winter, especially when it comes to surfing. Due to the rotation of the Earth, the storms that develop from the Iceland low will generally travel towards Europe, battering the coast of Ireland in particular. However, whereas these storms directly hit the coast of Ireland, Spain and Portugal are just far enough to have relatively calm weather, while being just close enough to receive some of the large waves. At the same time, Spain and Portugal have a complex coastal geography, full of sedimentary reefs and headlands. Whereas most sandbars cannot handle powerful higher period swell, reefs work especially well with these types of swell. Headlands are coastal land forms that extend into the ocean. They have an important impact on waves, especially on longer period swells. As mentioned earlier, waves extend into the ocean, and the longer the period, the deeper the wave extends. Therefore, longer period swells, extending deeper into the ocean, may feel friction of the bottom (wave shoaling), while their shorter period companions pass unaffected. Imagine some swell passing a headland. Here, long period swell will feel the bottom, while the shorter period swell doesn’t. When a wave feels the bottom it will be forced (like, being pulled) towards the coast; the waves start to bend in to the coast according to its bathymetry. This is how headlands may act as ‘swell filters’, only forcing the longer period waves, while letting the choppy short period swell pass. This phenomenon is amazing to see and especially important for surfing in, for example,  Basque Country, where you can suddenly find waves at places where you wouldn’t expect them.

This is why your best surf trip will start in September in France, with warm water, glassy conditions, oysters and wine. It probably won’t get any better than this, but still you could try to gradually move into Spain by late autumn. Then, when the rain starts to take its toll, and the pintxos lose their charm, you move down to Portugal. Here, around Lisbon, surf is at its best when wave heights over the North Atlantic are at its top. However, somewhere in spring the northern winds will start to pick up and you will have to move back up to France. Although I have never been there I heard great stories about Brittany in spring; fair weather, tasty cider and still some good waves. Finally, you may take the boat from Brittany to Ireland by June and surf in northeast Ireland over summer.

If you enjoyed reading this I can highly recommend Tony Butt’s books on surf science, his blog and his articles for Patagonia. Also, you could check work from William Finnegan, a passionate surfer who is writing for the New Yorker. In his biography Barbarian Days he takes you on his epic surf trips around the entire globe during the last century;  but while you read about surf history and waves, you also find out how it was to be a teacher during apartheid. 

By Floris Calkoen