I was recently hiking in Big Sur and noticed an effect on the ocean which I had seen before but not thought to ask about.
Basically, the water surface seems to have large-scale patterns on it. Look just to the right-of-center in this picture. You can see some irregular stripey patterns that appear to be colored more lightly than the surrounding surface. They are not themselves waves–the waves are much smaller. Nor are they foam or anything like that.
I noticed the patterns under other lighting conditions; I don’t have a good picture, but I was also able to see the effect within the sun’s reflection. It looked as if the patterned part was smoother somehow–it did not have quite the same sparkly texture as the other water.
My first thought was varying wind patterns. But why would the patterns appear to be so sharp? If there were varying wind speeds, one might expect them to make for more gradually varying patterns. Furthermore, the patterns were pretty stable, at least over the course of several minutes.
Another thought was the influence of undersea objects. But the water is pretty deep at that point and the waves shallow. Waves shouldn’t be influenced by objects at a depth of many times their height.
My last thought was that there’s some kind of surface contamination. I once read that a spoonful of oil can smooth the waves on a large pond. I don’t recall the explanation but perhaps the thin oil layer lowers the friction between the surface and the air and thus lowers the energy transfer needed to make waves. Maybe undersea kelp beds exude small amounts of oil, which floats to the surface and influences wave production?
In my experience, the pattern in the photograph is caused by kelp. The fronds come up to just below the surface and reduce the small waves cause by local winds, creating what looks like a “calm” area of smooth water. I’ve seen it may times up close, while fishing off the coast of So Cal.
Thanks, guys. So is it just the mechanical influence of the kelp on the waves, or possibly something else going on, like the oil film effect (first investigated scientifically by Benjamin Franklin) that I mentioned? It seems odd that kelp would always grow to the exact height needed to influence the waves mechanically but I don’t know anything about how it grows.
Kelp grows to just under the surface. Just like land trees, it wants to be as tall as possible to compete with the other kelp, but it can’t very well grow above the surface.
Kelp will keep growing. When it reaches just under the surface it spreads horizontally creating top cover for small fish.
It is very beautiful to swim 10-15’ down and look up at the canopy.
I’ve seen the same patterns in places were there is no kelp, I always thought they were produced by underwater features pushing water upwards, patterns of wind on the surface and slicks from passing boats or ships.
I searched a little and it seems that at least one cause are biological surfactants that may be produced on the surface or pushed up from deeper waters by currents.
Thanks! We were backpacking in the area around Cone Peak. I took that picture on one of the ridges above Limekiln State Park. I wish I had had my nice camera instead of a crappy cellphone, but lugging a couple kilograms around on a 15ish mile hike gets tiring. We spent 3 days hiking. Absolutely gorgeous sights from the ocean views to the redwoods deep in the valley.
Unfortunately we weren’t close enough to the ocean to see any sea lions or the like. We might have spotted some whales–we saw some disturbances in the water that slowly moved and periodically disappeared, but we couldn’t be certain.
Very interesting. I wonder if the microlayer can change properties at the scale shown in the photo. The stripes are pretty big–hundreds of meters wide and kilometers long–but I’m not sure how that would compare to variation in the microlayer.
No storms recently, but perhaps kelp regrows slowly enough in the winter that none was quite reaching the surface. Thanks for the link; I’ve only skimmed it but there’s an impressive amount of data in there.
They’ve yet to count the dried kelp float I’ve had hanging on my office wall for 25 years. Of course it’s 1000 miles inland, so they’re probably not looking very hard.
