Tag: waves

I’m getting more and more fascinated with wave ripples. I kinda understand how they form, but not enough to be able to explain as much about them as I would like to. For example below: Why is the pattern so different where sand has been washed on top of the shallow stones? Yes, the water […]

After doing a #friendlywaves post from a Norwegian fjord yesterday, let’s do another one from somewhere south of Bergen, by my friend Arnt. Very different mood today! What I find super fascinating about the picture below is how clearly you see the ship’s feathery wake in the reflection of the street lamps on the bridge, […]

The other day, my friend and co-author Pierré sent me pictures he took during fieldwork in a Norwegian fjord. As I, sadly, wasn’t there, all I can do now is admire the pictures and wish I had been there. And, of course, do a #friendlywaves — an interpretation of a wave field that a friend […]

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 […]

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 […]

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 […]

Using wave energy to generate electricity sounds very attractive, after all there are tons of waves and all they do (in addition to looking pretty) is eroding coast lines. But that’s exactly the problem: There is a lot of energy in waves, so wave power plants have to be extremely tough. Here is another post […]

After posting about how longer fetch leads to higher waves yesterday, here is why I was in that exact spot in the first place: To visit an old wave power plant on Toftøyna! The power plant was built in the 80s but destroyed only a couple of years after it had been built, so all […]

I just found this picture that I took back in May near my friend Elin’s cabin on an island in western Norway, and it’s a really nice illustration of how the same wind will cause very different waves depending on whether it’s blowing over the sea for many kilometres, or over a puddle for only […]

So you thought filling water into a tank was boring? Not on my watch! This is how we fill up the tank: Through a hole at the bottom. Which leads to a very nice fountain that slowly submerges as the water level rises: …and to tons of nice waves, which are great to observe! Propagation […]

Today is a great day for a wave riddle! Below you see a picture I took on my walk home the other day. Can you tell what caused those waves? (Solution underneath the picture!) In the picture above, we are looking at the curb and the lid of a drain. There are two ring-shaped waves radiating […]

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 […]

I can’t believe I haven’t written about this on my blog before, thanks Markus Pössel for reminding me of this great way to understand the Doppler effect! Doppler effect, or why ambulances change their sound as they race past you Doppler shift is everywhere, but it’s maybe not obvious how to imagine what’s going on […]

This still is one of my favourite kinds of wave field to look at. So calming. (Who am I kidding. All waves are my favourite waves, of course! I am addicted to wave watching…) Here is a short movie for you where you see the crests coming in from the bottom right and then being […]

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 […]

So many people are surprised when I speak of wave watching as of a “real activity”. But to me it is! So I am going to talk you through a couple of minutes I spent looking out on the water where the Kiel Canal meets the Kiel fjord, right outside the locks at Kiel Holtenau. […]

As you know we are currently preparing for future wave riddles. So this afternoon I went out for a wave hunt again and found something beautiful for you! The ship coming out of the Kiel-Holtenau locks into the Kiel Canal is making waves, but although those are pretty exciting, too, there are more things going […]

Today I have a couple of photos for you to prepare you for upcoming wave riddles. Since, in those riddles, I usually ask what might have caused the wave on that picture to look a certain way, let’s today look at a couple of relevant processes. A lot of processes can make or destroy waves […]

It’s pretty impressive when a mountain moves through a stratification and generates lee waves. But what I find even more impressive: The waves that travel behind the mountain when the mountain is long gone. See here: This kind of stuff looks more like a numerical simulation than something actually happening in a tank, doesn’t it? […]

Today I went on a wave-hunt expedition to take pictures for posts on the Froude and Reynolds number over at Elin & team’s blog (which you should totally check out if you haven’t done that yet! I am actually proof-reading my posts there and that is saying something ;-)) Anyway. Let’s look at the picture below. […]

Do you know the phenomenon that once you start noticing something, you see it everywhere? That’s been the case with me and total internal reflection. Not quite as impressive as last time, but still there: And what I found really interesting this time: a swarm of tiny fishies making wave rings! I only noticed them […]

Have you ever wondered why at some angles the sea looks blue (or whatever the color of the sky that day) and at others you can actually look into the water? That’s the phenomenon of total internal reflection. There is a critical angle at which you switch from “being able to look into water” to “total […]

It’s one thing to know that waves build up as they run from the open ocean over the shelf onto a beach, and that they build up as the water gets shallower and shallower. But we are so used to seeing exactly that (because that’s what the sea is supposed to look like!) that we […]

Such sneaky waves, sneaking around the corner there!

“Hei Mirjam. Bergen had it’s two days of allocated summer during the weekend of 22 – 23 July 2017 and Elsa and I decided to – in true Norwegian style – take advantage of the rare occasion and go for a hike. A colleague of mine has a “hytte” near Langhelle and had invited us […]

Joining a local club that gives me access to this whenever I like…

My sister took this amazing picture — and from a train no less! And I got super excited. Can you see the feathery wavelets* of the bow wave of that large ship? And then the wakes of both ships, spreading out at the same angle? I should definitely start spending time on high bridges going across canals, […]

I’m in this weird phase right now: In landscape pictures that I take, I like more than 2/3rds of the total area to be of water. That I like water shouldn’t really come as a surprise to anyone, but this perspective — looking from right above the water level towards the horizon — is new […]

If I take the wings of the morning, and dwell in the uttermost parts of the sea…

Last week, we ran an “expedition learning” course for 17-year olds. They were separated into several groups, working on different topics, and mine (unsurprisingly) worked on waves. You can see here what kind of stuff we observed when first testing the stretch of coastline we wanted to do our expedition to. And now you’ll get […]

Of course I did not only take pictures of lighthouses and instructional activities during the teacher training at Lotseninsel last week. I also took TONS of pictures of water! Some of which I’ll share with you now. For example below you see where the Schlei flows into the Baltic Sea. This is actually a fairly […]

This is an old picture from early spring, but I just love how the reflection of that pier shows up the different wave lengths so clearly. The longer swell wouldn’t have been visible just from reflections of the sky…

As you see from my parents’ attire and the lack of leaves on the trees, these pictures are not brand new. But still interesting: Do you see how the waves are bent towards the coast as they run into shallower water? And can you believe I still have to look up which one is refraction […]

I have always really liked the artwork you see below that was installed in Store Lungegårdsvann when I still lived in Bergen. But on the pictures here you also see how awesomely waves are diffracted around it. Pretty and interesting oceanography? What’s not to love? :-)

Awesome waves. Nothing more to say :-)

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 […]

Let me tell you the story of the picture below. I was walking along Kiel fjord with some friends and we saw this mama duck with all those tiny cute ducklings. We stopped and oooo’d and aaaaa’d and they were just so adorable!! But the after a while they swam on and we continued walking. […]

When a ship has sailed past, at first you see only its wake. And then you see reflected bow waves interfering with the original wave pattern: See?

I find it really fascinating to watch waves being bent by objects in their way. See how the wave is spreading out from the little slit? Or here how waves are coming in with straight wave crests that get bend once they run into the lee of the pier?

When I was talking about foam stripes the other day, you might have noticed that the foam stripe wasn’t a foam stripe all the way, but became “just a stripe”. And since I have been thinking about surfactants a lot recently, I think that’s actually what we are seeing in places where the stripe is […]

I really like it when waves reach a sea wall at an angle, because the resulting criss-cross looks so cool :-) And especially cool when you see it gradually building up, like below where the sea wall is partly protected by the gravel (or whatever you call those heaps of stones running in parallel to […]

One sunny morning, I noticed The Stripe again: Running all the way up and down the coast. In places where there is a large fetch the stripe is clearly foamy: But looking downwind from the pier the picture above was taken from, the foam stripe becomes just a stripe! And looking in the same direction, […]

The other day I found the perfect standing waves on a current: This egg-carton-like pattern really stays pretty constant over time and I think the changes in the wave pattern are mostly due to changes in the sand bed below! You see the sharp edge that is currently being eroded, and sometimes you catch bits […]

In July I will be involved in teaching an “expedition learning” course for a week. It will be all about coastal protection in the Kiel region, so two colleagues and I went on a private expedition to scout out what can be explored where. This is a very picture-heavy post, be warned! It’s more a note-to-self […]

I really like observing the wakes of ducks. Much easier to watch than those of ships because the scale is much more person-standing-on-the-sea-wall friendly. Also much less turbulence messing up the pattern. And you can get closer than you usually could. All three pictures from the same morning, taken within a minute of each other! Another […]

When I recently wrote about observing waves in a different way, I talked about light being focussed by the waves on the sea floor. In the other post, I focussed on how looking at the light and dark pattern on the sea floor makes waves visible that are otherwise hard to see when just looking […]

When we speak about “observing waves”, we usually mean looking at the water’s surface as an opaque surface that reflects the sky and where we see waves mainly due to being lit differently on different sides. But there are other ways to observe waves! For example by how they focus light on the ground below. […]

I recently borrowed a thermal imaging camera from work. So much fun! Below you see a cold sky, warmer trees and two really warm people walking through the park. One thing that really surprised me was to see reflections of the warmer trees on the little lake below. Although thinking about it, I am not […]

I think I might need to find a new route to walk along the Kiel fjord. When I was walking — in the most beautiful sunshine! — with my friend over the weekend, she pointed out that there are funny waves and it looked like there was water dripping in, and I went without looking […]

I recently googled for something related to the shape of waves and came across a photo of a wave that caught my eye, and it took me to a journey that lead to the article “nonlinear shallow ocean wave soliton interactions on flat beaches” by Ablowitz and Baldwin (2012). What’s discussed in that article is that while […]

The other day I noticed a funny wave pattern on Kiel fjord. Unfortunately I only took a picture where you see what caused the wave pattern: A step that was just at water level and got flooded with every wave crest and surfaced at every trough. See also in the movie below:

I think I might be getting closer to understanding the foam stripe mystery. Remember how we’ve always observed them going in parallel to the coast? Yesterday I saw this again, looking up the coast in one direction… …and down the other direction. I’ve had the hypothesis that they might be somehow related to Langmuir circulation, […]

…because they follow the coastline so nicely and I still don’t understand what’s going on there…

Waves going through very fresh, still flexible ice. What an exciting topic :-) We had a first look at the picture below in the last blog post already, when we looked at stages of ice formation. Can you see how the pancakes are deformed by waves going through? It’s a little more difficult to see […]

One thing I really like is watching ice form. Well, maybe not watching the actual freezing (don’t have the attention span for that) but looking at all the different stages. At first, you have all the small, individual needles that still slush around. Then, the needles start sticking together, and if there is a little […]

Shelter from the storm, no, shelter from the breeze. But we clearly see the sheltering effect of that boat shed on the wind waves… Same thing below. And wasn’t that a beautiful day :-)

No matter how often I’ve seen it, I still find it absolutely fascinating how the tiniest structures can have a really visible effect on the downwind wave field. Like for example that pier below, leading to the little hut at the end. There is probably a meter and a half between the water surface and […]

All you regular readers of my book and my blog surely recognize what’s going on below? Yes! A wave field comes in at an angle to the pier and gets reflected, leading to a chequered pattern. And a second wave field comes in with wave crests pretty much parallel to the pier, adding a little […]

Do you know the feeling when you, even on the most beautiful of days, want to get out of the pretty parks as quickly as possible so you can finally see the water? Especially when it’s foggy? And it is so worth it, there is always something to see. For example on that day: what […]

Wavelength dependency of wave-object-interactions. What a title! :-) But that is exactly what I observed over the enormous timespan of three full minutes (as shown by the time stamps of my camera) when I went strolling along Kiel Fjord one Saturday morning. First, I saw this old, overgrown tyre in a wave field that was […]

On Tuesday I talked about sea weed accumulating close to the sea wall in Kiel fjord, and I showed you the picture below. One thing that I found really interesting about that is how the floating sea weed dampens out all the waves. You can see it in the image above, bit it might be […]

I recently got a new comment on my blog post on foam stripes parallel to the coast, and since you guys hardly ever comment on my blog (I like getting your emails! Really! But why not comment on here? ;-)) it spiked my interest enough to look out for more foam stripes. So about a […]

Sometimes waves are very regular and mostly of the same length. Those are the ones that I usually talk about when I talk about interference of waves. But of course, other times, there are different kinds of waves with different histories and different lengths, and those do interfere, too. For example in the picture below, […]

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 […]

This post has been in the making for a very very long time. I have now decided to stop overthinking and just share the movie with you, because who wouldn’t want to watch the wake of a high speed catamaran? This is from my not-so-recent-anymore trip to Heligoland. Since I am too lazy to annotate, […]

Usually we see wave crests propagating, and since the eye can’t stop following them, it is easy to assume that they transport water with them instead of leaving the water put and just transporting energy. But here is an example of a situation where bubbles as tracers for water “parcels” show that, despite large waves […]

You can quite accurately predict when a wave is going to break. When it will break depends on its steepness, which depends on the slope that it is running up on. So due to the funny beach shape caused by the differential erosion on the upstream and downstream sides of groynes we can watch one […]

When waves run up a beach, they change their direction because for shallow water waves, phase speed depends on water depth (see this post for a nice little visualization for why the whole wave crest swings in towards the beach). Unfortunately, it is really difficult to take good pictures of this phenomenon, but I tried: […]

One thing I have been noticing a lot recently is how water changes coastlines (or even just paths in parks). Not really surprising, considering the enormous amounts of energy stored in waves that are released on the beach every couple of seconds. For example in Hastings, UK, the shape of the beach looked different after […]

It’s easy to forget the enormous size and power associated with waves in the ocean. Yes, we see pictures of surfers on Hawaii or of ships in waves occasionally, but usually we don’t really think about how large waves out in the ocean actually are. Which makes it easy to underestimate the force that the ocean […]

On my way back from London I had an almost equally interesting flight as on my way to London, which I talked about here and here. Except that most of the excitement this time round came from discovering that I wasn’t, in fact, sitting next to the person I thought I was, but that I […]

One of my favourite topics right now: Learning to “see” ocean physics wherever you go. For example here: A visit to my goddaughter in Schleswig, and this time we are practicing all she and her mom read about in MY BOOK (and if you have good ideas for a title for that book, please let me know!). […]

The morning I went to Heligoland I spent some time in the port of Hamburg, trying to film a phenomenon I had recently chatted about with the author of this inspiring guest post: How waves seem to propagate super slowly into smooth patches of water. It turned out to be really difficult to film (because ships didn’t […]

On my way to Heligoland the other day I noticed a phenomenon that I found really intriguing and that I should probably be able to explain. I first saw it on the screen of the boat’s web cams when we were about to leave the port of Hamburg. Unfortunately I could, at that point, only take […]

I recently went on a trip to Heligoland, Germany’s only island that is far away from the mainland (70 km in this case). It was a great trip, and I know you’ll be reading about it for some weeks to come :-) Today, we’ll just do the touristy parts, though, and get into the oceanography […]

As soon as waves run into water that becomes shallow enough for the wave to “feel” it, the waves start changing how fast they propagate. And depending on the shape of the topography, this often means that the waves change direction. This is called refraction and we can see it on many many different scales. On […]

I recently started looking at waves in “urban environments” (in contrast to “on the sea”) with a new found fascination. The reason why will be revealed soon, but for now just know that there are more waves coming up on this blog! Today, let’s start by looking at more waves on Store Lungegårdsvannet, like we […]

The most awesome thing about being on vacation is that I have the time to stare at water as much as I like. For example the other day, I walked around Lille Lungegårdsvannet on a windy day. Looking downwind, one sees a very smooth surface right in front of us, and then waves start developing further […]

Last night, we saw really nice wave phenomena on the Schlei in Schleswig. Do you see the waves being diffracted by the pier in the picture below? Waves are coming in from the right (see the three lines on the right in the picture below) and at the head of the pier they get bent around […]

Sometimes you need to look at the bigger picture to understand what is going on, especially when looking at phenomena on the water. My dad recently sent me the images below from Schleswig: Weird foamy stripes on the water. They don’t really make a lot of sense until you look at it from a different […]

When we watch rain falling on a water surface, we observe that each raindrop causes several concentric waves with different radii. In my post on Tuesday I just stated that that was what we observe, but today I want to look into the explanation. This is what it looks like when it rains on a water surface. Not much surprise […]

If waves spread equally in each direction along the water’s surface, then how come ships (or ducks) have wakes that are just those long lines of waves and not circular at all? So. Kids are typically familiar with what it looks like when you throw stuff in the water (for proof see below: my godchild on a […]

Last week I showed you the results of my “wave hunt expedition” on Aasee in Münster. Today, I am following up with the same lake on the day after and the day after that. Even more wave phenomena to observe! First, on my second day in Münster on my way to the conference: Clearly it […]

Hydraulic jumps, especially submerged ones, are a very theoretical concept for many students, one that occurs in a lab experiment if they are lucky, but more likely only seems to exists in videos, drawings, and text books. But we can observe them all the time if we know what we are looking for! They don’t only […]

A pier full of sail boats, perpendicular to the prevailing wave direction, and voila: Instant demonstration of an amplified wave! Look at how the masts show a transversal wave: Maybe consider bringing this video as a backup when you are not sure whether your class will be able to do this visualization of transversal waves and […]

Earlier this year at Forscherfreizeit Ratzeburg – the summer camp at which Conny, Siska, Martin, a bunch of teenagers and myself spent a week sailing, exploring and playing with water – I spent a good amount of time staring at waves hitting the wooden boards that form the slip in the port. They create a nice […]

The advantage of wind-less days on a sailing holiday is that you can play with water as much as you like. For example in order to look at the interference of waves, which is what I did. Check out the movie below! Sitting on the pier, playing, over time the interference pattern get more and more […]

Another one of those days where I kinda wish I had taken at least some meteorology at some point (only “kind of” because I wouldn’t want to miss any of the stuff I actually took…). But on my way to work I saw the clouds below: The internet says they might be cirrocumulus undulatus clouds. In any […]

The other day I was waiting for my friend and her daughter and noticed a weird stripe-y pattern in the distribution of algae. As I kept watching, the pattern started to change.At first I thought that maybe the algae were collecting in nodes of standing waves that were reflected from the sea wall (ok, lake […]

I remember being on a looooong walk on some Danish dike when my sister was small and really didn’t want to walk any more, telling her about how phase velocity of shallow water waves depended on water depth and how you could observe that when waves are refracted towards the coast (assuming the sea floor has the […]

In the last post, I showed you flow separation on a pylon in Elbe river. Remember? Today, we are back at the same pylon, only that this time the tidal current is a lot less strong, but there is a lot of wind, so our focus is on wind-generated waves. It might be admittedly a […]

When you throw a stick in the water and the waves don’t form circles. Throwing something in the water usually results in waves traveling out in circles from the point of impact. But if you throw your stick into a current, the waves get distorted. Watch the movie below! Slightly confusing that the stick drifts […]

Sometimes I am so glad to have this blog, just because it gives me permission to do things like film drops falling from a wet life vest into a pool with a calm water surface. Of course, nobody actually needs permission to do this, but it might seem a bit weird if you don’t happen to […]

My dear ship builder and naval architect friends, if this post seems horribly oversimplified to you, you are very welcome to write a guest post and go into this topic in as much detail as you feel is needed :-) So now my dear non-ship builder and non-naval architect friends, here is a post about […]

One of the reasons I have been wanting to do the vortex street experiment I wrote about on Monday is that it is pretty difficult to visualize flow fields (especially if you neither want to pollute running water somewhere in nature, nor want to waste a lot of water by setting up the flow yourself). As a first order […]

When a higher-order effect suddenly becomes important. During our excursion to Hamburg Ship Model Basin (HSVA), one of the experiments we ran was on Stokes drift. You can already see in that post’s movie that there is some swimming thing moving down the tank in the direction of wave propagation, but of course we had to quantify. “Experiment” sounds too […]

Excursion to Hamburg Ship Model Basin. I recently got to join a class on their excursion to Hamburg Ship Model Basin (HSVA, “Hamburgische Schiffbau-Versuchsanstalt” klingt so viel besser!). Those are amazing facilities and shipbuilding students are always excited to go there and get a glimpse at all the exciting research going on. Since they are working on […]

A very simple experiment to show how waves can travel around an ocean basin. I wrote these instructions for a book project that I was lucky enough to get involved in at the very last minute and figured I could just share them here, too. Why not try a new style every once in a […]

“At sea” in quotes, because technically we were at the mouth of the Weser river… But still! (deutscher Text unten) The really exciting thing working with the kids here at the JuniorAkademie is that they are really good at transferring things that we talk about theoretically to what they see in a tank experiment, and even […]

Creating waves and watching them interfere. (deutscher Text unten) You might not have guessed it from reading about our waves meeting over a sandbank experiment, but we weren’t doing in purely for its entertainment value. Our goal was to see how waves interfere, because the theory of interfering waves seems to be counter-intuitive in some […]

Creating waves in a tank. (deutscher Text unten) In the big tank, we have a paddle that is really good for making big waves. And if you create them in just the right way, they reflect at the back of the tank to meet up with the incoming waves right above the “sandbank” we put in […]

Looking at wave length, frequency and speed. (deutscher Text unten) The wave group played with a tank and a hair dryer (the hair dryer safely away from the water, obviously) and different modes of recording. high definition, slow motion and what have you. They also did a really cool data-model comparison, which is still top-secret, but […]

Standing waves caused by rocks in a current. I am incredibly fascinated by standing waves. The standing waves are caused by rocks sitting in a current. From the pictures below it is not really clear where those rocks are situated, whether they are upstream of all this wave action or in the focal point of […]

Just because it’s fun! :-) I’ve mentioned before that I tend to stare at water when nobody else seems to find anything interesting to look at. So just because I’m weird, let’s look at some more water. For example here. What could have caused waves like those below? Yes. These guys went past and what […]

Wind waves on one side of the current – no waves on the other. Recently in Bergen, I was walking to meet up with a friend at the kayak club, and I had to cross a bridge that has always fascinated me. Underneath the bridge, there is only a very narrow opening connecting basically the […]

Trying to create rogue waves in the bath tub of the infamous “red house”. As a part of their projects, students in the CMM31 in Isafjördur course had to conduct an experiment, document and interpret it. One of the students, Silvia, chose to create rogue waves in the bath tub of the “red house”, one […]

A tank experiment showing ship-generated internal waves. When entering a fjord from the open ocean by ship, it can sometimes be noted that the speed of the ship changes even though apparently nothing else changed – the wind didn’t change, the position of the sails didn’t change, the settings on the engine didn’t change – […]

Attempt at mechanistic understanding of Langmuir circulation. After  complaining about how I didn’t have mechanistic understanding of Langmuir circulation recently, and how I was too lazy to do a real literature search on it, my friend Kristin sent me a paper that might shed light on the issue. And it did! So here is what I […]

The experiment we run to discuss the velocity of shallow water waves. In this post, I discussed how it took us several years to modify an experiment to make it both student and teacher-friendly. But what can you actually see in that experiment? The movies below show the type of standing waves that are excited […]

Improving one of the experiments run in the GEOF130 lab. One experiment that has been run in GEOF130 forever is the “standing wave”, where a wave is excited in a long and narrow tank and then, for different water depths, the period is measured and the velocity calculated in order to compare it to the […]

Movie of waves being deflected towards regions of lower phase velocity. We are so used to seeing waves behave in a certain way that we usually don’t stop and think about why waves behave the way they behave. Imagine a headland with not-very-steep slopes, and wave crests approaching it. Consider now two possible scenarios. In […]

Video of different types of breakers – small scale. In this recent post we talked about types of breakers depending on the steepness of the slope. But even on a single stretch of coast line you can easily observe several kinds of breakers. My friend E lend her cabin on an island just outside of […]

Waves breaking on slopes of different steepnesses. Depending on a slope’s steepness, waves can break in very different ways. On nearly horizontal beaches, spilling breakers develop. On steeper beaches, plunging breakers, the kind of breakers that form the tunnels that people surf in, form. And on very steep beaches, the breakers don’t actually break, but […]

Movie on wave interference – two wave fields arriving perpendicular to each other, interacting and leaving. When talking about waves, it is often difficult to explain that wave heights of different components of a wave field can be added to each other to give a resulting wave field, but that each of those components continues […]

A seesaw to visualize how standing waves move in an enclosed basin. In enclosed basins, standing waves can occur. In the simplest case, they have a node in the middle and the largest amplitudes at the edges of the basin. The movement of the water’s surface then closely resembles that of a seesaw. Extremely simple […]

Visualization of progressive waves: wave form and energy move forward while the rope itself stays in place. When I talked about waves in GEOF130 recently, in order to explain the concept of progressive waves, I showed a drawing from one of the textbooks, where someone was moving a rope such that waves traveled on the […]

A photo of internal waves in the atmosphere. Internal waves exist on the interface between fluids of different densities. In the ocean they are mostly observed through their surface imprint. In the tank, we could also observe them by looking in from the side, but this is hardly feasible in the ocean. But luckily vision […]

A movie focusing on details of the lee waves in the tank. In this post, we investigated lee waves in a tank in a general way. Here, I want to show a detail of those lee waves: In this movie, the concept of hydraulic control becomes visible. On the upstream side of the mountain, the […]

How internal waves in the ocean can be spotted on the surface. Under certain conditions, internal waves in the ocean can be spotted at the ocean’s surface due to changes in surface roughness or to the movement of floating foam or debris. They can be spotted if half their wavelength is longer than the distance […]

Lee wave experiment in a large tank with a moving mountain. In this previous post, we talked about internal waves in a very simple experiment. But Geophysical Institute has a great tank to do lee wave experiments with that I want to present here (although it doesn’t seem to be clear what will happen to the […]

Internal waves are shown in simple 0.5l bottles. Waves travel on the interface between fluids of different densities and the phase speed of those waves depends on the density difference between the two fluids. The simplest way to demonstrate this in class can be seen below – two 0.5l plastic bottles are used, one half-filled […]

Using a photo from one of my research cruises to explain the formation of wind waves. Wind waves are (surprise coming up!) waves generated by wind that blows over the ocean’s surface. The size of those waves depends on several factors: The strength of the wind, the length of time the wind has been blowing […]