Wave train

When you look at waves, do you sometimes notice the train of smaller waves being pushed forward by the “main” wave? That has always fascinated me. Kind of like in the center of this picture:

Screen shot 2015-09-26 at 5.16.21 PM
wave train

When we were sailing in Ratzeburg earlier this year, one day there were hardly any wind waves on the lake, so putting a foot in the water from a sailing boat resulted in exactly the phenomenon that had puzzled me for so long.

In the movie below you see it “occurring naturally” and then afterwards “created” like in the picture above. I’m pretty sure it’s the “group velocity is only half the phase velocity” thing, with small waves passing forwards through the group and vanishing, only to be replaced by waves coming from the back of the group. Is this what is happening here? Anyone?

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