dispersion relation – Adventures in Oceanography and Teaching

Phase and group velocities in deep and shallow water

mglessmer — Mon, 14 Oct 2019 12:45:58 +0000

When Tor came to visit me in GFI’s basement lab a couple of days ago, he told me about an experiment he had seen in Gothenburg in the seventies. So Elin and I obviously had to recreate it on the spot. Therefore today, we are comparing phase- and group velocities in deep and shallow water! […]

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Playing with roll wave animations

mglessmer — Wed, 30 Jan 2019 07:25:32 +0000

I love how powerful Powerpoint is, at the same time there surely is a way out there to create these kind of animations with a little less copy & pasting, and especially without manually moving tons of stuff by juuust a tiny little bit from frame to frame? How would you build these kinds of […]

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I’m explaining your wave pictures: A #friendlywave from the Île d’Yeu, France

mglessmer — Mon, 28 Jan 2019 13:50:49 +0000

The whole #friendlywave thing (where I explain your wave picture) is starting off great! Here is one that reached my via my Twitter; link to thread here. What’s going on in the north east of Île d’Yeu, France? Here are four pictures from the Twitter thread that got me intrigued: Because of the awesome waves […]

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Roll waves, one of the more complicated #friendlywaves I’ve gotten over the years…

mglessmer — Mon, 28 Jan 2019 08:36:44 +0000

#friendlywave is the new hashtag I am currently establishing. Send me your picture of waves, I will do my best to explain what’s going on there! When it rains, it pours, especially in LA. So much so that they have flood control channels running throughout the city even though they are only needed a couple of […]

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Why are they so much slower than I thought? Observing the group velocity vs phase velocity of waves

mglessmer — Thu, 04 Oct 2018 08:08:30 +0000

Have you ever seen a speedboat drive past, looked at its wake moving torwards you, then gotten distracted, and when you look back a little while later been surprised that the wake hasn’t moved as far towards you as you thought it would have during the time you looked away? Well, I definitely have had […]

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Wave watching: Refraction and diffraction of waves

mglessmer — Wed, 19 Sep 2018 13:20:42 +0000

A little more wave watching, today with a focus on how waves change direction when they run into shallow water. Let’s look at this beautiful wave and see what happens when it reaches the shallow shore. Above, you see the wake of the pilot ship, consisting of many wavelets that propagate as parallel wave crests towards […]

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Shallow water waves

mglessmer — Thu, 08 Jun 2017 09:55:51 +0000

Have you ever noticed how, if you are at a shallow beach, no matter how choppy waves are further offshore, everything becomes nice and orderly on the beach? Below you see where the water depth suddenly increases, both from the color of the water and from the wave pattern. While in deeper water waves propagate […]

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Watch the dispersion relation in action

mglessmer — Tue, 18 Oct 2016 09:32:51 +0000

Remember how we talked about how waves seem to propagate extremely slowly into that calm patch that occurs when a boat pulls away from a dock? Well, the other day I noticed that there is even more physics you can see when watching a similar situation: You see how long waves propagate much faster than […]

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