Welcome to a new feature on our blog, think of it as your Sunday morning read. A chance to get up, sip your coffee and learn something new, or enrich your knowledge on something you already know a lot about. Gary Larson, will take you through the science behind the things we all enjoy, but aren’t really sure exactly why/how they happen in his course Surf Science 101. Enjoy!!
Ladies and gentleman summer is upon us and that means south-swells are aplenty. You’re excited for the 18-20 second, New Zealand ground-swell from about 200° but not exactly sure why? Well, feel free to saddle-up for the inaugural weekly installment of Surf Science 101, where I will attempt to enlighten you on some of the perplexing phenomenon we, as surfers, often encounter in the ocean. This week I will be exploring the formation of ocean waves, the variables involved and how they can travel for thousands of miles before breaking along the coastline.
Contrary to the explanations I have heard, from middle America folk to the well seasoned Southern California surfer, waves that we surf on a daily basis are not caused by the moon, tides or the large freighters criss-crossing the ocean. The only variable that is absolutely essential for wave propagation is wind. That’s it. If the planet Earth ditched its moon, ceased all tidal fluctuations and sank every boat in all seven-seas, but wind still blew over the surface of the ocean, we would still have waves.
That being said, there are three important factors that govern wave heights; wind speed, wind duration and fetch. Fetch is understood as the distance over water that wind blows in approximately the same direction. If there is an increase or decrease in any of these three variables the wave height will either increase or decrease, respectively. For example, if a 40-knot wind blew for 24 hours over a 100 mile fetch the wave heights would be larger than if the wind speed was 30-knots and the fetch was 50 miles.