Diffraction at RSPB Conwy

This was going to be a piece about how the ripples on the water help us to see the invisible gusts of wind. Each gust sent a set of short wavelength ripples across the surface - an interesting real-time visualisation tool. But it didn't photograph well. However, I did notice that as well as the high frequency noise on the surface, there were also lower frequency waves crossing the pond.You can see them in the clearer water beneath the clump of reeds in the water in the middle of the picture. Why are they suddenly visible there? The answer seems to be that their wavelength is closer to the size of the clump so they are able to bend into the sheltered space behind the clump by diffraction. The much shorter wavelength noise isn't able to diffract and so goes straight past.