Making waves and watching them disappear

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Happiness is: Making waves, watching them spread, watching them disappear.

Here, you see waves that I made by gently rocking a small row boat. You see them radiating away from me…

Below, I set off a set of waves.

And watched it travel away, over the lake, the water quickly returning to the smooth, undisturbed surface it had before I interrupted it.

See how the set of wave is traveling away from us still, while the water surface inside and outside of the wave ring is almost completely flat?

And now the waves are only visible at the far end of the pond, and the reflection close to me is back to almost perfect.

Do you love to make waves just to watch them? I do! :-)

A #friendlywaves from Cyprus

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My friend Alice (of the awesome Instagram @scied_alice and the equally awesome blog, which you should totally follow) sent me a #friendlywaves from her trip to Cyprus. She said that this was a simple one, so I am looking forward to what else she has up her sleeve once I pass this test ;-)

So here we go with the pictures she send.

Clearly, she is on a boat trip, and she’s looking back at the wake of the ship. You see the one side of the feathery V of the wake, pretty much in the middle of the picture. On the “feather” closest to us, you can still make out the turbulent part of the breaking bow wave, where the water surface looks all crumpled up and not as smooth as it does further away from the ship. Actually, this is a really nice example to show that the waves are traveling away in the wake, but the water is not: All the other “feathers” further away have smooth surfaces as they have run away from the ship’s trajectory, while the turbulent wake traces out the exact path where the ship went (as long as there aren’t any currents moving around the water, which we’ll assume for now).

Picture by Alice Langhans, used with permission

The waves in the V-shaped wake are fairly steep, you can see them very slightly tipping over on occasion.

And Alice sent a second picture: Similar situation, except now it’s a little more windy. The turbulent wake is a little more foam-y than in the previous picture. This could be because the ship is sailing faster, or because it’s more windy. I would guess the first.

And when I say “sailing”, I am using this as the technical term for a ship driving. I am assuming that the boat Alice is on is not a sailboat. I’m thinking this because the wake looks fairly turbulent and sail boats usually don’t cause this much turbulence; also the little bit of the boat that I can see doesn’t really scream sailboat to me. We’ll have to wait to hear what she tells us, though!

Picture by Alice Langhans, used with permission

On both pictures, there is hardly any swell visible. Waves are usually not as visible when the water is deep as when they run up on a beach, and so far off shore we can assume that the water is fairly deep. But that also means that it isn’t very windy, hasn’t been very windy recently, and hasn’t been very windy anywhere near recently, either, so no large waves have traveled into the region.

So much for these #friendlywaves. How did I do, Alice? :-)

When commuting is actually enjoyable. #wavewatching

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What I love about my job (in addition to the awesome job itself, obviously)? That my office is located in pretty much the coolest spot in Hamburg when it comes to touristy views of the city. So much great wave watching (and ship watching) to be done here!

For example below, see the small ferry on the right, and how well you see the bow waves in this kind of light?

And below, it has turned and is heading out into the main Elbe arm and you can spot the turbulent wake that reflects the sun very differently from the rest of the water on either side.

And then just casually strolling past dry docks, container terminals, huuuge ships…

I really enjoy this every day! Hamburg, the gateway to the world.

Hijacking other people’s “good morning!” tweets to talk about a duck’s wake

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A beautiful picture: the pink sky, purple clouds, a peaceful channel flowing in between lush greens that the calm water surface mirrors back, a bridge somewhere in the background, connecting the shores, both in reality and in the image on the water. Early morning harmony. Hygge?

And what jumps at me?

Waves!

Which I think are really beautiful: Featured in the dark images of the trees on the water, a duck’s wake reflects the light sky back to us, thus becoming visible. And once we spot the V in the waves, with the almost invisible duck at its tip, we can see how the space between the feathery sides of the V is filled with half circles, connecting the feathers. They get more and more difficult to see the further away from the duck we look. The contrast becomes less clear where they aren’t set against the dark backdrop, and the more the waves dissipate with time.

This kind of waves is so common all around us, all the time. Did you ever really stop and look? It’s so worthwhile to really observe these things, to me that is happiness :-)

The Teltow channel and the bridge connecting Lankwitz and Steglitz, by Henning Krause. Picture used with permission

Spotting both the V-shaped and turbulent wake of a faraway ship on a calm day

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The title says it all, I guess ;-)

In the picture above, you can still see the ship on the left, and having seen the ship, I am sure you can recognise the turbulent wake in the picture below, too: It’s the lighter blue stripe towards the horizon with darker, rougher sea surface to either side.

And in the top picture, you see individual “feathers”, i.e. parts of the V-shaped wake with the ship at its tip, coming towards us, whereas in the bottom picture, a little later, the one part of the V has reached us and we see the “feathers” as the wave crests that are more or less perpendicular to the bottom of the picture.

I find it interesting how the perspective makes it seem as if the wavelength gets a lot longer towards us, but that’s really only the perspective. Also the closest two or so crests are really hard to see — can you spot them? The closest one you can see better on the right side of the picture where there is a sudden change from a darker to a lighter part coming across, and the second one you see more easily on the left side, again, with a quick change between darker and lighter. And the third one is fairly easily visible all across the picture.

Do you do wave watching when you are at the water?

Rambling a bit about why I am blogging, and about why I love watching Latte (#kitchenoceanography, of course!)

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So, for anyone coming to this blog post because of the nice stratification you see at the bottom of the latte in the picture above — do you know the process causing the layers is very similar to the one that caused the awesome fingers and rings in my tea the other day? You should check out this blog post for what’s going on there exactly!

And now that you are here, let me tell you a little about why I am blogging, since I’ve been asked about this a lot recently.

First and foremost, I blog because I need some way to archive my thoughts and materials on mainly #kitchenoceanography and #wavewatching, but also on relevant literature in STEM teaching and outreach, and some other things I find interesting. Short, anything that relates to my “Adventures in teaching and oceanography” (which is actually the name of my blog, even though my website admittedly doesn’t make that very clear right now). As you can probably imagine, I take tons and tons of pictures of waves (that never end up on the blog, which I should probably just delete, but it seems easier to mark the ones I like and upload them rather than deleting all the stuff that isn’t quite right) or of drinks (coffee or tea, doesn’t matter) or all kinds of other stuff that is vaguely oceanography-related. I take them because I just find them fascinating (FASCINATING! FASCINATING!!!), but also because I will want to maybe use them some day for either teaching, or science communication, or maybe for a new edition of my book. Or something else, who knows? But anyway, I am taking them for myself, and publishing them on my blog, where I can tag them and put them in categories and search for them easily seems to be the easiest way to do so.

But even though organising my stuff for myself is my main motivation day to day to take and upload pictures, I know that there are surprisingly many people following this blog, and also I believe that science communication and sharing fascination is super important. And while my blog started out with readers being mainly colleagues-that-were-also-close-friends, by now it’s also a lot of people that I have never met personally. And for you — anyone who is fascinated by water and all its forms and all its processes, or for you who stumbled on this blog and has no idea what’s going on but is kinda intrigued by it — I try to put more than tags and key words on the posts, and I add posts like the one on Pierre and my not-so-recent-anymore article on how to teach about the Coriolis force. Because I hope that people might either find something that is interesting to themselves and makes them want to learn more about the ocean, or because they are looking for teaching resources and then find pictures they can use to illustrate phenomena with, or ideas, or explanations, that will hopefully inspire others. And that’s what I am doing on those Saturdays on my sofa: making my blog accessible to people other than myself in the hope of spreading the fascination with the ocean :-)

Ok, that’s it for today. I’ll leave you with the picture below that I took the same day and that I really liked because of the colors and the way the building is peeking in on the right edge of the picture (did I mention I NEVER use filters and I hardly ever even crop my pictures? Yep, that’s how lazy I am). Looking at the picture below, we could of course talk about how we can see the wind on the water, or the reflection of the sun, but the picture isn’t really suited for that, there are better ones on my blog already to show that stuff. It’s just a pretty picture, and because it’s my blog, it may stay ;-)

Determining the slope of sea surface via the reflection of a structure

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(Disclaimer: The physics the title refers to are somewhere in the second half of the blog post when I am done rambling)

In case you are wondering why I am blogging so much all of a sudden: Sometimes I just love to spend a couple of hours on my sofa, drink something warm, and play with my blog (as I told you I would last Saturday, when I wrote all the stuff that got published recently [technically it’s still said Saturday morning as I am writing this, I am just scheduling all these posts to be published over the next couple of days. I usually select and upload the pictures I want to use on my blog the day I take them, and I always know what I want to write about them, too. In case you were wondering about my blogging process…]). Anyway, moving on.

The pictures for this post were taken a couple of weeks ago, when it was still feasible for me to be at Kiel fjord in the mornings when the sun was this low. Early bird and all, but these days the sunset is too early to just accidentally observe.

What really irritates me is how the condensation trails in the sky look like scratches on the picture. Even though I took the pictures on my phone and then watched them on the phone’s screen (so there is no way they could have gotten scratched somehow) I kept thinking they were scratches. But the pictures are still pretty…

But what the low sun made really easy to observe because of the sharp contrasts between lit and shaded sides of the structure, is how you can actually use the deformation of the structure in the reflection to determine the slope of the water’s surface.

As you know, you can only see the reflection of whatever is exactly in the pathway of the ray from your eye, reflected at the sea surface, and going out at the same angle it came in. Even if you were looking in the same direction all the time, if the slope of the surface changed, what you could see in the very same spot would change, too. Hence if you look at reflections on water, they move and get deformed as waves go past the spot you are looking at…

Above, looking at the white hand rail’s reflection, it becomes very obvious that the wave field is actually quite complex. There are waves that pull the hand rail’s reflection out to the right side, and those that move it up and down in the picture. I find it absolutely fascinating how some parts of the hand rail are visible several times in the reflection, how there are even bits of handrail that seem completely detached from the rest (see the little white dot inside a white loop somewhere in the bottom right?) and how the whole thing still seems so organic and smooth.

Below, you even see how you can see how each wave crest relates to a “spike” in the reflection.

When looking at waves in pictures, it is usually pretty difficult to see which parts of the pictures correspond to which side of the wave, the one facing us or away from us (unless, of course, the waves are breaking, or you see stuff like total internal reflection going on). But the reflections make it a little easier, I think.

And just because staring at the reflections made me feel a little dizzy, here is something to give your eyes a little rest: The view towards the Baltic Sea out of Kiel fjord.

Hope you are all having a nice day full of #wavewatching! :-)

A “Siel” – the valve in a dyke that lets freshwater out but no salt water in

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Ok now, after complaining about how I dislike mud and the “no water” (i.e. low water) times in the Wadden Sea yesterday, today I’ll tell you about some stuff I really love about the North Sea coast. For example, the pretty little villages full with shrimp trawlers everywhere!

Picture above is Neuharlingersiel, below is Dornumersiel.

And the pictures below are from my favourite “…siel” so far, Greetsiel. Even though I unfortunately didn’t take any pictures of the village itself! I was so fascinated with all the shrimp fishing vessels.

The boom trawlers with all the colorful nets and ropes and everything are just too pretty, even on an otherwise fairly miserable day!

But what I find fascinating in all the “…siel”s is how they bring together a nautical atmosphere (after all, most of these ships have been out on the open North Sea all night!) and a very inland-pretty-old-town vibe. And here is how they do that: with the “Siel”. The “Siel” is basically a valve that lets freshwater out into the sea, but which doesn’t let salt water come back in. The way that is done by doors that are opened if the pressure on the inside (i.e. the land side) is higher than on the outside, and that close if the pressure on the outside is higher than on the inside. Pretty smart, ey? That way the land gets drained during low water, but no salt water comes inland to mess up the agricultural land. But I find it fascinating how this one little door in a dyke can separate two completely different habitats that coexist peacefully just one step away from each other.

Above, you are looking from the inland on such a “Siel”, which is currently closed because the water is higher on the outside than on the inside.

Oh, and what I always love: Light houses!!!

Yep, so I definitely have to go back. Stay tuned! :-)

The wonders of a Wadden Sea. Or what someone addicted to #wavewatching thinks they are

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As someone living on the German Baltic Sea coast, I don’t spend a lot of time on the North Sea coast (except, actually, my week-long vacation after Easter with my godson and his family, and when my friend Frauke and I went to Sylt earlier this year, or when Frauke and I are going back to the North Sea next weekend. So maybe that’s actually not so little time on the North Sea coast compared to most other people?).

Anyway. I really like the North Sea, especially because I like the flat landscape where the highest points are dykes.

What I really dislike, though, is getting my feet muddy. But that’s pretty much the whole point of a North Sea vacation, according to my godson and his family.

On the other hand, though, having the opportunity to actively and directly influence water depth (or, as normal people would probably say, leaving footprints in the mud) makes for some pretty cool wave watching!

It’s a little hard to see, but if you look at the picture above, you see that the sun is coming from kinda behind my left shoulder, and the picture below is taken from a similar perspective (just telling you so you can interpret the footprints and resulting waves). So the left edges of the footprints are actually coming up and partly out of the water.

The wind is coming from the right, and you see the locally generated wind ripples and how they get defracted around the obstacles created by the foot prints!

Pretty cool, eh?

In the picture below, the wind is coming from the left and you see the muddy wakes of the fresh footprints! This I think is pretty awesome, especially because you at the same time see the refraction of waves around the obstacles.

What I also think is pretty cool are the little spaghetti piles of sand that the worms living in the mud leave behind.

And that, for each of the piles, there is a funnel somewhere close by, and a worm connecting the two inside the mud!

But then when the water is gone completely, it’s still pretty here, but also a liittle boring. Don’t you agree?

Ok, but it’s still pretty. But Wadden Sea and tides take the fun out of wave watching for quite substantial amounts of time every day, and I don’t approve of that ;-)

Influence of wind and water depth on a wave field (or: a beach vacation in Dornumersiel)

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I took the selfie above mainly to send to my mom from my vacation in Dornumersiel on the German North Sea coast. But then when looking through the hundreds of pictures I took that day, I realized that not only was my hair parted on the wrong side because it was so windy (ha!), the wave fields to my right and left looked actually quite different, without the reason for that being immediately obvious. So let me show you a picture facing the other way.

Above, you see this wave breaker like structure, protruding into the sea. The wind is coming from the right side, thus the waves are a lot larger on the right side of the breaker where they are getting more and more energy from the wind as they come towards us, than the waves on the left, the lee side of the breaker, where they don’t get any new energy input and are just refracted around the breaker.

Looking the other way, towards the shore, the difference becomes even more clear (picture below) isn’t this fascinating?

I really like watching how waves interact with structures. Below, for example, we see that the wave crests are coming towards the wave breaker at an angle, and that they are reflected and traveling away from it, too. This contributes to making this side look a lot more choppy than the other side!

On the other side, the waves look smooth. I was still standing on the breaker when taking the picture below, and you see where the sea surface is still sheltered from the wind and where the fetch is long enough so the surface roughness increases and ripples and capillary waves form.

Since we are in the Wadden Sea, the shore has a very shallow slope going into the North Sea, so waves look super interesting when they are in the shallow water. Below you see many many almost-breaking wave crests behind each other, coming towards us. The water depth is clearly a lot less than a wave length, the waves are interacting with the bottom and thus have really long and uniform troughs and steep, short crests. (btw, for those of you wondering how I could say anything about water depth in my #friendlywaves post on Saturday: This is how. This is an example of waves in very shallow water, and you clearly see their shape being different, don’t you?).

I love looking at the details of where they hit the beach! All the sparkle, all the little Mach cones around the pebbles where the water is running off, all the small capillary waves!

Below, someone accidentally walked into my picture, but that’s actually a good thing, because it gives you a scale, and if you look at the little wave rings that were created when she put her foot into the water and it splashing forward a little. The wave rings actually have comparable sizes to all the other small stuff going on on the sea surface!

And what’s also pretty impressive: How the crests get refracted by changing water depth. Below it almost looks like parabolic shapes coming in from the right, right? The side of the parabola that is further away is actually the wave crest that is coming in from the open sea, and the rest, i.e. the actual curved part, is partly diffraction around the breaker and then refraction because of changing water depths. So cool!

Since I spent quite some time there, here is a picture later that day with a lot less water. Tides and all that… ;-)

And then another day with a different wind direction and less sun.

I think it looks really cool to see the fairly wide area to the right of the breaker, in its lee, where the surface is really smooth!

So far, so good. Gotta go now! Do you find this as fascinating as I do?