Tag Archives: wave watching

Wave watching at the locks in Kiel Holtenau

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Yes, we are back to wake watching! Today I went to a new-to-me wave watching spot: The bridge across Kiel canal close to the Holtenau locks, which you see in the background of the picture below. And I should have checked out my favourite ship tracking app for better timing, I had to wait for quite some time before there were any ships apart from the small ferry which you see crossing right at the locks! But the wait was well worth it in the end!

In these pictures, you see very clearly the different parts of the wake. The turbulent wake right behind the ship where the ship has displaced a large volume of water and where the ship’s propeller has induced a lot of turbulence. The turbulent wake is bound by the foam created by the breaking bow waves. And outside of all of this, the V of the feathery wake opens up with the ship at its tip.

I am super excited about these pictures. Do you see the wake reflecting on the right (south) side of the Kiel canal?

And while it was pretty easy to interpret the pictures above, and the one below is still fair game because the turbulent wake of the third ship is still clearly visible, even though the ship is not, it is getting more and more complicated, isn’t it?

But now, with two of the three ships gone, it has suddenly gotten a lot more complicated. And it doesn’t help that the sides of the canal aren’t completely straight which leads to the mess in the lower right corner…

This is definitely a new favourite wave watching spot which you might see more of in the future! This stuff makes me so happy :-)

Wakes by birds, a row boat, and a SUP board

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After talking a lot about turbulent wakes this week, here are two pictures of different kinds of wakes. They are of course turbulent, too, but on a very different scale.

In the picture above, see how you see pairs of eddies on either side of the row boat’s wake? That’s where the oars were in the water! But this wake stays visible only for seconds, maybe a minute. Nothing you would be able to see for a long time from afar!

Same for the waves the birds made. Can you still spot that they were swimming in the same direction as the row boat and then made a 180° turn? Maybe you can, maybe you can’t, but that’s how quickly those wakes vanish.

Now below: This is a very interesting wake. Since the SUP board is pretty much flat on the water and doesn’t displace a lot of water while moving through the water, it pretty much only creates the V-shaped wake, not a turbulent one the way a ship does when it’s displacing a large volume of water in order to get forward.

Think I’ve said everything there is to say about waves? Well, then just enjoy this one from the ColorLine ferry that sailed past a couple of minutes ago… How beautiful is this? :-)

Visiting my friend’s office for some #wavewatching

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Since we seem to be on the topic of wake watching these days, here are some pictures I took when visiting my friend Liz at the European Cruise Service’s offices in Bergen the other day. She had already told me about the awesome wave watching to be done from their meeting room, but see for yourself!

Above, you see a very nice example of the turbulent wake of that cruise ship substantially modifying the wave field even after the ship is gone (or, in this case, after the ship has turned to leave in the other direction. Doesn’t this whole picture look very Titanic? Or is that just me?). What is going on there is that the turbulence introduced in the water by the ship and its propellers moving a lot of water around sticks around for quite some time. While the water is still moving due to the turbulence, “normal” surface waves can’t propagate in the turbulent area. The water’s surface thus looks very smooth there, a lot less rough than in areas where there are wind waves. And the smooth areas reflect light similarly to a mirror, whereas the rough areas’ light reflections seem to resemble maybe a disco ball?

Below, you see both parts of a wake quite well: The turbulent wake right behind that ferry (which will show up all smooth from a distance), and then the feathery V wake (with the ferry at its tip) that spreads on either side of the turbulent wake.

And you see some more old turbulent wakes in the picture above, for example one that the ferry in the foreground is following closely (see how it stretches out before the ferry?) and one that turns left to go towards the invisible Askøy bridge (you can still make out the ferry where the wake begins).

Do you see the potential of this wave watching spot? I definitely have to come back!

Even if you are not into wave watching, it’s a super interesting place to visit because it gives quite an interesting look on the city, even with Ulriken being disguised by the low clouds that day…

Would you be interested in a wave watching tour when you visit Bergen (or Kiel, or any other place)? If so give me a shout, we might be able to arrange something ;-)

#wakewatching seems to become a thing for me

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Usually I look at wakes when ships are long gone, or at least leaving. Today, let’s look at one where the ship is coming towards us and we see how a bow wave turns into the feathery V-shaped wake!

That’s actually all I want to say today. Except look at how well you see where the pilot ship changed course in the picture below! And I love that color. Always makes me happy to see that ship! :-)

Is #wakewatching the new and improved #wavewatching?

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It all began when I spotted a wake (the feathery, dark line going across the water behind that boat house) and decided I needed to show the world how cool it is to do #wakewatching.

Check it out in the images below:

The water is pretty calm, apart from some locally generated wind waves. But there is a long, feathered wave crest coming in. What I mean by feathered is that it’s not actually one continuous wave crest, but several crests that propagate shifted from each other, but in total forming what seems to be one long line. In the left of the picture below you can actually see the two wave crests that follow each other closely.

A little while later you can see the wake starting to interact with the shallow bottom — wave height increasing, and the sea wall — waves reflecting.

Below you see that the wave actually starts breaking when the water depth becomes too shallow.

And below you see the wave crests that were reflected on the sea wall!

The reflection is actually easier to see when we look down the other way: See the Vs with their tip at the sea wall, exactly where the original wave crests is transformed into the reflected wave crest?

Next time you see a wake approaching a sea wall, you should look out for these pattern — a couple of minutes well spent! :-)

Reflecting waves, reflected and refracted light, and a Fata Morgana

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How much physics can you spot in a single picture?

What I see here:

  • Waves and their reflection on the sea wall (Do you see the two main fields? One coming in from the top right, and then the other one (technically the reflection of the first one) going out to the top left)
  • Total reflection of light: Looking at the water surface at steep angles, we can look into the water and see the sandy sea floor and some stuff growing on it. At small angles, all we see is the reflection of the sky (and see how the angle we look at the water surface at depends not only on the direction we are looking, but also the local orientation of the water surface that is deformed by waves!)
  • The way light is focussed on the sea floor by the incoming wave field, creating these bright lines parallel to the incoming wave crests, but nothing similar going on for the reflected wave field
  • The Fata Morgana might be a little difficult to see, but if you click on the picture below, or even more clearly in the one at the bottom of this post, they will enlarge and you can see the light house (on the horizon, between the bird and the ColorLine) seemingly balancing on a rock with a very slim base, when in reality the base of the lighthouse only gets wider towards the ground…

And then there is of course lots more physics to see:

  • A bird flying
  • A ship swimming
  • water vapour condensing into clouds and condensation trails
  • a breeze changing the texture of the water surface

What else do you see?

Long-distance wave watching during sunset

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Have you ever noticed how much you can observe when you look at water from a distance? For example in these pictures, you see the tracks of ships that are long out of sight! Do you see the circle that one obviously drove before leaving our field of view?

For the ships far out in the fjord, you can’t actually see the waves so much as the turbulence they created that left the surface smoother, thus better reflecting the light from the low sun (and appearing yellow-ish). And how cool how you see how newer tracks run over older ones! Only for the ferry in the bottom left you can actually see the waves themselves.

In the picture below we actually see the waves that both ferries made.

Zooming in: How cool does it look to have these waves almost all the way across the water? And do you see how they are bound by the ship’s V-shaped, feathery wake? I find it really fascinating that there are such large surface elevations, but only inside of the ship’s wake.

I just love wave watching, even when I am not even that close to the water :-)

Fascinating how the same body of water can show up in so many different colors at once!

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Stupid as it sounds, one of my favourite wave watching spots in Bergen is a busy bridge with a view onto another busy bridge. But the bridge goes across a very narrow opening which connects Storelungegårdsvannet, which you see in the pictures, with a fjord and ultimately the open ocean. As the opening is a lot narrower than both the fjord and the lake at the fjord’s head, there are pretty much always strong tidal currents going one way or the other, sometimes leading to a substantial difference in sea surface height on either side of the bridge. I found that quite scary the first couple of times I had to paddle through!

But what I found most fascinating today is how many different colors you see on the water, and how they are all explained by different physical processes.

If we look at the bottom end of the picture above, we see that we can look fairly well into the water and see the sandy/rocky bottom with some algae growing on it. You can look into the water so well because several things came together at the time when I took the picture:

  • There weren’t a lot of waves to disrupt the view
  • I’m looking into the water at quite a steep angle, so even though the light going in and out of the water is refracted at the interface, the angle is too steep for total reflection to happen
  • This lower area of the image is reflecting the dark underside of the bridge rather than the bright sky, making it easier to see the muted colors in the water because there isn’t too much interference with bright colors from elsewhere

Moving on a little up in the picture above: Here we see the reflection of the sky (see the clouds reaching down the slopes of the mountain? (If you don’t see what I mean, check out the image at the top of this post where you can see it both reflected and “for real”)

We see the reflection here because the angle is a lot shallower and we don’t have the bridge’s shade making it possible to look inside.

Notice how the bridge’s reflection doesn’t have a sharp edge but shows up all the turbulence in the water? You can also notice more turbulence on the right side slightly above the middle of the image.

And then there is this grey stripe going all across the reflection of the mountain and houses. That’s where a little breeze is going over the surface, creating ripples. Since the surface is rougher now, we get a lot of bright sky reflected towards us.

Below another image, where you see both sides of the bridge’s reflection. Isn’t it fascinating how turbulence is distorting the reflection? And there is a lot more turbulence on the left than on the right at the bottom end of the bridge’s reflection, where you can still make out the railing of the bridge in the reflection…

In the uppermost image, you also see that it becomes more and more difficult to see the bottom as water depth increases – the water seems to be getting greener and greener, darker and darker.

What else did you spot that I didn’t mention? And do you think you’ll look at Storelungeren the same way as before next time you cross that bridge? ;-)

#wavewatching in the sky

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On Elin’s student cruise (read more about that here) very nice wave watching was to be had, both on the water as well as in the sky.

In the picture below, if you look slightly left of the mountain top in the right of the picture, you see five parallel cloud stripes — evidence of the air moving in a wave motion after going over that mountain top! This motion results in clouds being there for certain phases of the waves and then no clouds for others, and since the movement is periodic, this results in cloud stripes. Now if I knew more about cloud formation I could probably tell you what changes with height except for pressure, and how that results in cloud formation or no cloud formation, and hence whether the cloud stripes indicate wave crests or wave troughs. My gut says troughs. Does anyone know?

Another very nice wave pattern is seen below: Kelvin-Helmholz instabilities! Those are shear instabilities that will eventually start breaking. Unfortunately I went back to work and next time I looked I didn’t find them again.

Commissioned wave watching: Eckernförde edition on a beautiful calm and sunny Sunday!

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Recently, more and more of my friends send me pictures of waves they spotted when walking along a lake side or taking a ferry ride. I love how contagious wave watching is, and I love sharing my fascination with you! :-)

Here are some pictures that Fred sent me of his lovely Sunday walk today. There are at least five interesting things that I notice in the picture below. How about you?

  1. Look at the beautiful interference pattern where two wave fields are almost perpendicular to each other, creating the checkerboard pattern! As you see in the picture below, there is one wave field coming in at a 45ish° angle to the sea wall, so its reflection is at 90ish° to the original wave field.
  2. In the background you see the surface roughness changing and the water seeming darker where there is a breeze going over the water, creating small ripples that reflect the sky in a different way than the smooth surface closer to us.
  3. See the waves the seagull made where it landed on the water?
  4. Looking at the foreground, do you see the tiny ripples that show up not so much on the surface of the water, but rather at the sandy ground, because they focus the light?
  5. And notice how you can look into the water in the foreground but not in the background? That’s the awesome phenomenon of total internal reflection where, if you look at water at an angle that is smaller than a critical angle, you cannot look into the water any more but just see light reflected at the surface! One of the things I never understood we had to learn about in school, but that I find super cool now.

And in the picture below, what do you see?

What I find most interesting in the picture above is how the reflection of that storehouse tower looks different in areas with different surface roughnesses. Where there is a breeze on the water in the background and in the foreground, it’s a lot more spotty than in the calm and smooth surface in between. And the checkerboard waves pattern (now you see the seawall that created the reflection, btw) carries through to the reflections, too, with the blue crisscross going into the white area where a cloud is reflected.

And then the phenomenon of total internal reflection is really clearly visible here with a lot of reflections on the water (or just more interesting things to reflect than just a blue sky in the previous picture) and a view down to the ground only in the very foreground of the picture.

Thanks for sharing these beautiful pics, Fred!