(fast moving x 9) L 070428u0749
(fast moving x 9) L 070428u0749
(fast moving x 6) L 070423u0616
The density waves may even appear to start from a line, and from that line diverge towards two different directions.
Intermittent density waves.
Some kinds of density waves, seen on a video, seem to be swinging back and forth, in a swift alternance, intermittently. The movement is only apparent. The water is still, but it keeps changing its density, and therefore its volume.
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