When the ocean is still, i.e. there aren't waves that disturb the surface, you often see "lanes" of water that seem flat as opposed to areas where the wind causes ripples. What causes this?

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There can be many reasons for the lines that you see where the water is not rippled.

1) There is no wind on those specific areas. Not likely in the photo used as the example but especially when there are cold fronts involved the wind can be very inconsistent over short horizontal distances.

2) You may be seeing the influence of boat wakes that passed over the area recently.

3) You may be seeing variation of the underlying ocean currents. Especially near the coast with tide changes there can be zones of significant ocean current. Wind and ocean currents have an influence on wave height and shape. When the wind blows against the current you get higher steeper waves. When you get wind blowing with the current you get shorter shallower waves (the smooth sections). The currents are not just horizontal but have vertical components as well. The lines identified could be vertical eddies in the current smoothing the surface whereas the smooth / rough line in the foreground is were the major ocean flow is going in opposite directions to each other.

4) If the coast in the foreground is shallow and there are waves coming to shore there then the lines identified to be rip currents caused by water returning from the coast line.

From my personal experience I would say that you are seeing variations in the surface ocean currents, and these currents change how the wind develops waves on the surface.


  • $\begingroup$ I think #3 is applicable in this case, since the lanes tend to be in the same place over time. $\endgroup$ – user8389 Jun 22 '17 at 21:04

Expanding on Friddy's third point, this could be the surface signature of what are called internal waves (https://en.wikipedia.org/wiki/Internal_wave). The smooth regions indicate upward motion of internal waves and the rough regions indicate downward motion of internal waves. More information can be found here: http://www.whoi.edu/oceanus/feature/the-waves-within-the-waves

  • $\begingroup$ Interesting...I knew about gravity waves I just never considered them internal to the water but when you consider the possibility of different water densities due to temperature or salinity it makes sense that subsurface wave, rather than mass movement, could cause observable surface features on the water. I will watch for this phenomenon in the future. $\endgroup$ – Friddy Dec 21 '17 at 18:29
  • $\begingroup$ Internal waves often visible in the atmosphere. They can be frequent in mountainous areas. An example, as seen from an airplane: physics.fullerton.edu/gwpac/news/highlights/… $\endgroup$ – John Dec 21 '17 at 22:57

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