Timeline for Why do water surfaces have persistent "average wavelength" patches?
Current License: CC BY-SA 4.0
21 events
| when toggle format | what | by | license | comment | |
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| Feb 22 at 13:39 | comment | added | Toffomat | Note that I would guess that the lighter "lanes" in your seocnd picture are wakes behind a ship, maybe one that's turning | |
| Feb 22 at 13:38 | comment | added | Toffomat | These eddies can easily (more or less) stay in a place for minutes, if the wind is generally steady and tehre is some obstacle. They may also move with the gusts - when you're sailing, you learn too look out for those patches because they tell you where the wind is. | |
| Feb 22 at 13:26 | history | edited | Robert Wegner | CC BY-SA 4.0 |
added 92 characters in body
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| Feb 22 at 13:21 | comment | added | Robert Wegner | @Toffomat at which timescales would you expect these structures to persist? I would imagine that these small eddies created locally by some wind should spread out and disperse. But the shapes visible in the picture are persistent over minutes! | |
| Feb 22 at 11:17 | comment | added | Toffomat | I don't think that has anything to do with oil, this is quite typical even for rivers or lakes without boats. Rather, there are probably two effects: (a) Wind creates eddies which lead to rougher, darker water surface locally -- in your photo, wind is probably from the right, so the right part of the river is shielded by the slope. (b) Turbulence in the water (not just the surface) suppresses wave formation, so the wakes of ships (turbulent due to the propellers) are less rough, hence lighter. | |
| Feb 22 at 9:52 | history | reopened |
John Rennie David Bailey LPZ |
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| Feb 19 at 8:59 | review | Reopen votes | |||
| Feb 22 at 9:52 | |||||
| Feb 19 at 8:58 | history | edited | Robert Wegner | CC BY-SA 4.0 |
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| Feb 19 at 0:38 | history | closed |
AlphaLife Miyase David Bailey |
Duplicate of Why does the lake surface appear darker in some areas? | |
| Feb 18 at 20:28 | review | Close votes | |||
| Feb 19 at 0:38 | |||||
| Feb 18 at 20:11 | comment | added | AlphaLife | Does this answer your question? Why does the lake surface appear darker in some areas? | |
| Feb 18 at 19:14 | comment | added | Robert Wegner | That is pretty convincing, I think they're oil patches now. That's fascinating. | |
| Feb 18 at 18:46 | comment | added | Chemomechanics | Yes, these look like areas of relative smoothness resulting from oil resting on the surface. Pop-sci explanation video. | |
| Feb 18 at 18:26 | comment | added | Robert Wegner | @hyportnex well yes the wind generates waves, but it does not generate waves localized to a patch a couple of square meters in size. | |
| Feb 18 at 18:25 | comment | added | Robert Wegner | @Chemomechanics I mean you have surely seen patches as in my photo before. Do you really think it's oil? | |
| Feb 18 at 17:26 | comment | added | Chemomechanics | “it doesn't really make sense that there would be so much oil everywhere.” Why? I see oil-using boats everywhere. It doesn’t take much. | |
| Feb 18 at 14:50 | comment | added | hyportnex | these short (relative to depth) wavelength surface waves are very dispersive and unless are being driven they do not go far and quickly disappear, see en.wikipedia.org/wiki/Capillary_wave and en.wikipedia.org/wiki/Dispersion_(water_waves) | |
| Feb 18 at 13:10 | comment | added | Robert Wegner | The appearance of waves and patches in general is surely due to the wind, but for me the wind does not explain the persistence. | |
| Feb 18 at 12:18 | comment | added | hyportnex | most likely wind driven | |
| S Feb 18 at 11:07 | review | First questions | |||
| Feb 18 at 11:16 | |||||
| S Feb 18 at 11:07 | history | asked | Robert Wegner | CC BY-SA 4.0 |