Can swells cancel each other out?
He's mistaken.
Swells don't "cancel each other out". He's merely looking at a map of peak wave period, which is displaying the direction/period of the swell train that has the most energy.
That being said, I've been researching nonlinear wave-wave interactions for a while, which can affect surf conditions as the wave energy is redistributed across the spectrum under certain swell conditions.
But in general, the theory states that swells from opposing directions will generally pass through each other without any significant loss of energy.
That's incorrect.
Swells can at a point in time cancel each other out, ie destructive interference, but then at another point amplify thanks to constructive interference.
When watching them arrive at a point on the coast, both would be there and clearly visible though cross-hatched with various amplifications and troughs.
Remembering that a lot of the energy sits below the surface and these swells travel 10's of thousands of kilometers through other swells, winds etc.
But if the energy is substantial enough it won't be affected at all by another swell from another direction.
What he's trying to depict from the charts is just the peak wave period of different swells interfering with each other with one overriding the other (as a visual) not in real life. This is just a side effect of the way those charts are displayed.
Thanks for the input fellas. Aligns with my observations.
Side note, does anyone know which breaks around Lima or Punta Hermosa are good in those big NW swells? Most of the info in Lima talks about SW swells and most info on NW swells is for the north of Lima places like Cabo Blanco.
Not sure.. sorry mate. Peru's been on the to-do list for a while though!
I’m heading to Peru for a while with the fam and have been digging into insta a bit to get some info. Found this guys reports and I was surprised when he so casually mentions that big SW swells “cancel out” a big NW swell there when they hit at the same time. He mentions it in other videos and it seems like it’s a thing over there? The physics book says that yes waves can cancel each other out via destructive interference and I guess this is how noise cancelling earphones work.
My question however is what’s your experience with this? Especially on the east coast of Aus as I’ve never heard it talked about here that I can remember and we get swells from different directions hitting at the same time often. If anything it seems to be a good thing here with “combo swells” “active seas states” and generally more energy in the water. My own observations have always been just seeing two different directions hitting the beach at the same time and seeing sets break differently according to which swell they are hitting from.
What say you SN?