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During storms, I have often watched ocean waves breaking at the shore as if they were in slow motion. I've wondered if the slow curling of the waves during these times was somehow due to their increased power, when compared to waves breaking faster under calmer conditions. However, it has occurred to me that remarkably slow breaking of the ocean waves during storms when viewed from the shore may also be due to opposing force vectors of air and/or water currents, such as air rushing through the trough under a wave curl, or air and/or water currents opposing the wave action in another manner somehow. I have noticed these slow wave movements even when the wind is coming in strong from the ocean, which one might presume would make waves break quicker. Is there a simple correlation between the power of a wave and its breaking or curling speed?

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  • $\begingroup$ I've also observed waves breaking slowly counterintuitive to the sea and wind from the sea conditions. I've justified it with a stronger push from behind, i.e. an easier building up of the breaking wave. Not sure it makes sense but like more water is ramping up than that falling. $\endgroup$
    – Alchimista
    Aug 4 '20 at 10:55
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There are long papers published just on this topic! The rate, and height, of a wave's transition from smooth sinusoidal form to breaker depends on its speed, wavelength, and crucially on the rate of change of water depth as the wave approaches land (or reef, or whatever). Waves only break because the deeper portions of the wave are slowed down due to frictional interaction with the ocean floor.

This is separate from the mechanisms which cause "whitecaps" on open water, where the wind reaches some critical speed and is able to more or less tear the peak section of the waves loose from the body of the wave.

Fluid dynamics is to blame for both these behaviors; I fear I am nowhere near expert enough to identify the exact formulas to apply.

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  • $\begingroup$ Thank you. I would probably not understand any equations and appreciate the explanations. I had not thought of the proximity of the waves to the ocean floor. $\endgroup$
    – Sketcher
    Aug 4 '20 at 16:36
  • $\begingroup$ Could something as in my comment to the question take place? Of course one has to assume not a changing depth between different observations at the same shore. I assumed the fall basically gravity related while the piling up enhanced by the storm condition. Like that the "on the way to break" vawe is pushed/kept up by the incoming water (at that point water moves, isn't really a wave...). $\endgroup$
    – Alchimista
    Aug 5 '20 at 8:47

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