Rethinking Langmuir Circulation lanes

A couple of weeks ago…
… I asked what I thought was a simple question about “lanes” of quiet water that one can see on bodies of water. Here’s that Challenge:

2. As we’re sailing from place to place, it’s not uncommon to see large patches of water without any ripples on the surface. It’s something you see nearly everywhere–it’s a common effect on lakes, ponds, and oceans. But what causes these ripple-free regions on the water? (See below for an image that has a large Y-shaped blank area in the middle. What causes this?)

I offered this image as an example of what I meant. See those blank spots?

And I found this other picture (see this Y-shaped quiet area in the left-center).

I tentatively identified them as lanes caused by Langmuir Circulation.

BUT THEN, as I was driving past the mouth of the Gualala River (in Northern California; it opens onto the Pacific) I saw THIS:

Here’s a closeup below. Notice how the lines are VERY parallel, and run through the tree stump, and right onto the grassy shoreline at left. This is pretty clearly caused by Langmuir Circulation cells in the water. And yes, the wind was blowing (fairly hard) exactly along the lines. If you notice, there are lots of small waves on top of the cells. That’s NOT quite what I was looking for: I wanted to find the cause of those glassy patches.

But as I stood there looking at them, they were NOT the same as the quiet / ripple-free regions I’d seen (as in the first two pictures above). These are clearly Langmuir cells, but there are LOTS of tiny wavelets on top of the water. Looks to me as though we’re searching for another process than wind-induced long, linear cells.

So… what’s going on?

I don’t know. The search continues!

Let me know if you run across anything that’s relevant to the “quiet water” effect.

Still searching!