Total internal reflection
In the “static apnea” discipline in freediving, many cool pictures of athletes are taken underwater in a way that plays with the reflection of the athlete in the still water…
Category: observation
Solar eclipse!
The effort that went into today’s solar eclipse is nothing compared to the one in 2015, when we made it the topic of a workshop on how to use PBL in…
Insta takeover on snowflake formation
Back in December, I did a takeover of the Instagram account of WissKommSquad, a community of german science communicators. I translated it over new years, but somehow never published it.…
Marine energy: Tides. A guest post by Manel Camacho
Today’s guest post is brought to you by Manel Camacho. Manel and I met on Twitter and bonded over our joint love of wave watching — me as a dedicated…
New #WaveWatching series happening over on Elin’s blog: #BergenWaveWatching!
Kjersti, Steffi, Elin and I recently discussed ways to better integrate the GEOF105 student cruise into the course. Right now, even though students write a report about their work on the…
Fog showing stream lines around cruise liner
Whenever I get out of my house and it looks like this, I am slightly disappointed because it means that the wave watching that morning will not be ideal. I…
Lüneburg — how a few centimetres in distance separate two seemingly completely different bodies of water
Sightseeing is best when it involves a little water watching, like for example last weekend in Lüneburg. Doesn’t it look intriguing below, the change from a calm, mirror-like surface to…
Watching the tides cause an hydraulic jump in the Irish Sea!
Looking at the picture above, taken in the South Walney Island Nature Reserve on our walk yesterday, what is the first thing you notice? For me, it is not the…
Enjoying the South Walney Island Nature Reserve
Wanna come on a walk with me and Astrid around the southern tip of Walney Island? This is what our parking spot looked like when we arrived (we did park…
An art & science collaboration with Wlodek Brühl: #dropphotography
If you are here because you saw my title or talk at the Science in Public conference in Manchester and are curious about #dropphotography as a form of art&science collaboration in scicomm…
Opening speech for Wlodek Brühl’s art
You might remember that I had the honour of giving a speech at the opening of Wlodek Brühl’s art exhibition back in spring. Preparing my presentation for the Science in Public…
Algae as tracers for currents in Parsteiner See
Remember how I described a breeze creating a wave field on Parchsteiner See? Well, it did not only cause a wave field, it also set up a circulation! Which I…
Soap bubble musings
I have too many soap bubble pictures from last weekend’s trip to Kleinwaabs to not write a post about soap bubbles. So let’s get right into it! First thing I…
A “Siel” – the valve in a dyke that lets freshwater out but no salt water in
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…
Who enjoys playing with water clearly even more than me? An eager beaver!
Work took me to Brodowin (a village northeast of Berlin that is situated in a biosphere reserve and does amazing organic farming). The public transport, however, only took me to…
Roll waves in the sand dunes? Observing erosion
On our trip to the west coast yesterday, I observed something really cool: Sand roll waves (I think!) in the sand dunes! But before I get to that, this is the…
A different kind of drop photography today…
After all the professional drop photography I talked about yesterday, here is some of my own from a walk that I took after the amazing and slightly overwhelming experience of…
Vernissage of “liquid art”: The perfect opportunity to combine art & physics to do some scicomm!
If you don’t want to “preach to the choir”, how do you, as science communicator, reach new audiences occasionally? One way that I tried today is to give the (invited,…
Intriguing interference pattern of waves
Do you see those weird traces going away from us, perpendicular to the wave crests, but in parallel to the bright stripes on the sea floor (I talked about those…
Wave watching by proxy — looking at how waves focus light on the sea floor
What is it that we actually look at when we go wave watching? Water is pretty much clear (or at least it is in the spots where I like to…
Wave watching at the locks in Kiel Holtenau
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…
Vernissage of water sculpture photography by Wlodek Brühl, with explanations of the physics behind the pictures by yours truly!
I am a huuuge fan of Wlodek Brühl’s liquid art: Pictures of water sculptures that are created with focus on the tiniest of details, that only persist for milliseconds, but…
Roll waves, one of the more complicated #friendlywaves I’ve gotten over the years…
#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,…
My escalator analogy for Froude numbers
The Froude number Fr=u/c is the ratio of a typical velocity of a current (u) and the phase velocity of the typical waves in that area (c). It thus describes…
Commissioned wave watching: Eckernförde edition on a beautiful calm and sunny Sunday!
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…
How to use home-made surface drifters to teach oceanography
Very early knowledge about oceanography stems from beach finds that had to have been transported to that beach from far away because the finds themselves (pieces of trees, or coconuts,…
Forget about big waves, today we are focussing on the details!
Today we are focussing on tiny waves right near the shore inside the sheltered harbor. See how below there are two wave fields, one with longer waves with crests that…
More wave watching, this time in Kiel
Beautiful morning arriving back in Kiel… Looking downwind, the weather might seem pleasant (especially when focussing on the sunrise). But looking upwind however, the wind rows on the water as…
Sunset wave watching in Gothenburg. Wakes under different light conditions!
Wave watching from high up gives you a whole new perspective on wakes, and depending on the lighting, features in the wave field become more prominent or fade away. See…
Wave watching on Kiel Canal: Bulbous bows and how they shape the wave field
Even when I fully intend to just go for a Saturday afternoon walk to catch up with a friend, this is what happens… I get distracted by waves. Like the…
Minimal distractions from #wavewatching on a foggy Sunday morning in Kiel
I’ve been wondering. Are foggy mornings where all you can see are waves (and a couple of seagulls) opportunities on which everybody else sees the world like I always see…
I see a new hashtag in my future #oceanographyofpuddleswithreflectionsofElbphilharmonie
There is a theme these days: one of Hamburg’s most famous sights, the concert hall called Elbphilharmonie. And not only is it a pretty impressive buildings, it’s located right at…
Here is to new beginnings!
From dawn til dusk (which wasn’t actually as long a time as it sounds ;-)), first day in my new job as programme manager of the citizen science project on…
Where has all the water gone?
You might have noticed that in today’s first post there was a lot less water in the Kiel fjord than in yesterday’s post (starting this year strong on the blogging front! I…
Ferry sailed past, wake perpendicular to wind. Cool interference pattern!
Guess the title says it all today ;-) Just kidding. Below you see a movie of a neat interference pattern I observed this morning. The situation is similar to yesterday in…
When the ferry has long sailed past and the waves start appearing out of the fog…
Ending 2018 in style and exactly the way I want to continue in 2019: wave watching and dipping into Kiel fjord! 2018 has been an exciting year and a lot…
Turbulence watching
I am super excited by how the upper-left-to-lower-right plane‘s turbulence is visible in the destruction of the awesome feathery remnants of the middle-left-to-slightly-up-on-the-right plane’s condensation trail. Bonus: that bird!
Visiting the ruins of a wave power plant — waves running up a funnel to fill a reservoir
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…
Visiting the ruins of a wave power plant — waves driving a turbine
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…
Same wind, different waves, or: the influence of fetch length on the size of waves
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…
Did you know that uranine starts fluorescing again when the ice cubes melt?
Yes, I had to test that! :-D Why do I find this exciting? Because that means that a phase change of the water switches fluorescence as a tracer of that…
Did you know uranine doesn’t fluoresce when frozen?
Something else I found out when checking on my ice cubes yesterday: I had frozen a second tray* with ice cubes dyed with uranine (you know, the green stuff I…
Why are they so much slower than I thought? Observing the group velocity vs phase velocity of waves
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…
At the end of the rainbow you’ll find … home-made surface drifters
For Lars Henrik and Harald‘s GEOF105 class we are deploying home-made surface drifters on the student cruise. Today I had the opportunity to join the cruise again, and since the weather today made…
Taking water samples
A big part of any oceanographic research cruise: Taking water samples. Here is a group of students practicing how to arm Niskin bottles that will go into the ocean open…
Home-made surface drifters
A bicycle safety flag, a plastic bucket, four paint roller trays — what are those people doing there?! Until now this might almost count as kitchen oceanography! Home-made surface drifters But it’s…
Rainbows in regnbyen Bergen
Yesterday when approaching Bergen airport, I saw something super cool: The lower half of a rainbow! Even though I grabbed my phone and snapped a picture in record time, I…
Balances of dyed and un-dyed waters
Oh look, a plume of (almost) un-dyed water hitting the green lake! I am really fascinated by the balance between green water leaking out of the pipeline and into the…
The first autumn storm and its impact on dye tracer and water level
Last night it rained a lot. So the first thing to do this morning was to check what that had done to my green lake! The dye is now a…
It’s all about the right equipment: That’s why I now own a UV lamp! I see a lot of fluorescent tracer spotting in my future!
Before I start gushing about my awesome new UV lamp (thanks for encouraging that purchase, Uta! :-)), some other updates on the state of green in the park across the…
Fluorescent night walk — following the stream through the lake into Kiel fjord!
Luckily some of my friends are crazy enough to bring the UV lamps and go on a night walk with me, following the green fluorescent stream! (Don’t know what I…
Dye tracer “in the wild”, day 2
This morning, the green lake looked different yet again. If you remember yesterday’s pictures, we ended the evening with the lake being a fairly well mixed green color (picture on…
Dye tracers “in the wild”
You know I love dye tracers (remember the beautiful fluorescent green we used in the 2017 experiments in Grenoble, when we got to play with the 13m diameter rotating tank?)…
“Liquid art” by Wlodek Brühl, and how it could be used in physics teaching
Do you sometimes feel that wherever you go, you just happen to observe something that makes you think about physics? I definitely do, and that’s what happened to me again…
Reading the water — a new mystery picture for you! Today: Kiel Holtenau edition
Do you sometimes like to play detective when looking at water and figure out who or what caused certain pattern on the surface? Then I’ve got a nice riddle for…
Layered latte: A great real-life example of double-diffusive mixing!
Sometimes sitting in a café for a work meeting with #lieblingskollegin Julia can lead to unexpected discoveries of oceanographic processes — in my latte! It’s those little things that inspire blog…
Guest post: Using seawater to make bread!
Last week I got one of the coolest emails I have ever received: Someone had found my blog while googling for the salt content of seawater in order to use…
Alexander’s band: the dark space in between a primary and secondary rainbow
Bergen is a fairly wet place with on average 240 rain days every year. But that actually provides us with the perfect opportunity to see plenty of rainbows. Here is…
Waves in a density stratification. One of the most beautiful tank experiments I’ve ever seen.
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…
Tank experiment: Lee waves in a fancy density (and dye) stratification
Did you seriously think we’d stop tank experiments with only 2-layer systems? Nooo! Today, the plan was to set up a continuous stratification, which I have been planning to do…
Lee waves in the tank
Did you guess what we needed the stratification for? Yes — we are moving mountains again! :-) What we want to look at: How a current reacts to an obstacle…
Kelvin-Helmholtz instabilities
I’m back at my happy place — the teaching lab at GFI in Bergen! :-) Here a quick look at what we’ve been doing today: Filling the large wave tank!…
Experiment: Interference of waves
Interference of waves is something often taught either using light as a practical example, or without a practical example. Here I want to show a couple of observations as well…
Asking students to take pictures to help them connect theory to the reality of their everyday lives
— This post was written for “Teaching in the Academy” in Israel, where it was published in Hebrew! Link here. — Many times students fail to see the real-life relevance of…
The mystery of Lokksund. Mysterious as ever, and I am still intrigued…
Forget climate change and all the big questions, there is this one thing that is really bugging me because I haven’t figured it out yet, but I really want to:…
“Laboratory layered latte” – combining latte and double diffusion. Easily my favourite paper ever!
My friends know me well. Especially A&I, which was proven again when they sent me the link to an article about two things that I am mildly obsessed with: Latte…
Let’s guess tides!
Actually, there is no need to guess. If you tilt your head 45 degrees to the left, you are looking at Hamburg the way it would be shown on a…
Eddy on the beach
It’s bugging me that I don’t really understand what’s going on here or why… But look at how these eddies form on the beach right outside my window and for…
Candles in the wind. Or: The things that keep a nerd entertained during speeches at a conference dinner.
What keeps you entertained at conference dinners is probably different for different people, but we quite enjoyed watching how the candles placed closer to the door to the balcony burned…
Whale watching on the Azores
Whale watching on Terceira was A-MAH-ZING. We saw three different kinds of dolphins: Bottle-nose, common and spotted. But what you should really be doing once you are done swooning over…
Why the Isère reminds me of a water jet pump
This is what the way to and from the 13-meter-diameter rotating tank in Grenoble looks like (and you should really visit Elin & team’s blog to learn about all the exciting…
Wave watching Sunday in Grenoble
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…
Foam pattern when hard-boiling eggs
Today we have foam patterns again, but of a very different kind than usually: I don’t know if I have just never noticed before (I can’t really imagine I would…
Total reflection and fishies
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…
Total internal reflection
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?…
Mussel filtering water
And something more from the teacher training at Lotseninsel: A mussel that sucks in water dyed with food coloring and then pumps it out on the other side again. Very…
Flatfish and mud
Here is something else I filmed during teacher training at Lotseninsel: how some flatfish (that the other group caught close to the island) digs itself into the mud. Pretty cool…
Amplification of waves when they run into shallower water
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…
Awesome interference pattern in a Norwegian fjord
“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…
Feathery wavelets and wakes
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…
Sea urchin & star fish
At work (at the Kieler Forschungswerkstatt) there are a couple of fish tanks with interesting stuff in them. I made these videos ages ago but just thought I’d share them…
Reflecting the sky
Even though I mostly look at the water to see waves, sometimes it is also really nice to just watch the reflections of the sky…
Café Latte
Even though most people think I am crazy, I always love watching the convection pattern develop in a hot drink.
Awesome reflection of a wave train
This is a really good way to train your eyes to spot reflections of waves: watch a single wave train hit a sea wall: Please don’t get sea sick when…
No foam stripes
In fact — no water! I thought it was worth mentioning that this situation exists, too ;-)
Empty ships
I know I wrote about it last time I sailed to Gothenburg, too, but empty ships look weird! But watching ships and ports is always so much fun :-)
More than 2/3rds need to be water
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…
Tiny islands, shelter from the storm and the wings of the morning
If I take the wings of the morning, and dwell in the uttermost parts of the sea…
Refraction of light in ship exhausts
Leaving the port of Gothenburg after our mini cruise, A and I obviously had to secure the prime spot for wake watching because I wanted to check out more of…
Wake of the Stena Germanica — what’s going on there?
After having talked about wakes quite a bit recently, I’m going to show you a couple more pics today (bit not as many as I did two days ago, sorry!…
More wakes
And now you thought I was done showing you wakes? Ha, I was not nearly done! I told you, watching waves makes me happy :-) And from Stena Germanica’s sun…
Expedition learning
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…
Wakes and what they do to the sun’s reflection
When I said that wake watching made me happy last week, did you really think those were all the wakes I was going to show you? Ha! No, I have…
Weekend wave-watching
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…
Reflected wake
The best ship-watching of the year happens during Kiel Week (even if I do a fair bit of ship-watching year round ;-)) But this year, I was absolutely fascinated with…
Wave watching
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…
Refraction of waves towards the beach
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…
Diffraction of waves around obstacle
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…
Traces in the sand
Yes, I am really that fascinated by sand that this is the second post in a week about it. And I still think the picture below looks like the place…
Wind direction
Sometimes stormy beaches are just as interesting as stormy seas. Can you spot the prevalent wind direction below? ;-)
Locks at Kiel Canal
The locks at Kiel canal always make for interesting weekend strolls. I love watching ships! Especially armed with my favourite app, VesselFinder (similar to marine traffic described here), because it…
Playing with a thermal imaging camera
Today I’ve been playing with a thermal imaging camera. Below you see a snapshot of my experimental setup, but before I tell you more about that experiment, a little bit of…
Shallow water waves
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…
Duckies, a drama and a wake
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…
Reflected wakes
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?
Diffraction
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…
Surfactants
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”.…
Waves reflecting on a sea wall
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…
Foam stripes
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:…
Standing waves in a current
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…
Expedition learning
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…
Wakes of ducks
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…
Burning foam
One weekend, my godson’s family took me to the Explorado Duisburg, Germany’s largest museum for kids. And one thing we learned there was to make foam that you can ignite…
Group velocity and phase velocity
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…
Observing waves differently
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…
Playing with a thermal imaging camera
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…
Wind field
Another boundary layer experience last week: On my way from work I stopped to take pictures of flags that were outside my university’s main building and that very nicely visualised the…
On the impact of blogging — or how far does my message mix?
What is the impact of this blog? And who am I writing it for? Those are not questions I regularly ask myself. The main reason I started blogging was to…
More funny waves
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…
Nonlinear effects in shallow water waves
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…
Optics
I’ve even talked about it on this blog before, but I find it still fascinating how every tiny droplet manages to flip the world upside down :-)
More foam stripes
As you might have noticed, I am getting a little obsessed with those foam stripes. Another day, a little more wind, looking up the coast: And down the coast… Do…
Funny waves on Kiel fjord
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…
“Coriolis fountain”
We’ve been thinking about Coriolis deflection a lot recently (see links at the end of this post). But this weekend, at Phaenomenta Flensburg, I came across a so-called “Coriolis fountain”.…
Foam stripes mystery — closer to figuring out what’s going on?
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,…
Foam stripes again…
…because they follow the coastline so nicely and I still don’t understand what’s going on there…
Ice and waves
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…
Ice forming on Kiel fjord
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.…
Desublimation: When water vapour freezes to ice without becoming liquid in between
One of my favourite phenomena right now is desublimition, or deposition: The phase transition of water vapour to ice that doesn’t go through the liquid phase. It happens when moist…
Shelter from the storm
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…
Wind waves
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…
Refraction of light in moving water — why stuff seems to be jumping around
I was waking along Kiel fjord one morning and noticed a stone “jump” on the ground as waves went over it (and actually, that observation was the motivation to dive…
Refraction of light in water — looking at a couple of examples
Looking at how light gets refracted when it enters water is always fascinating. There are a dozen blog posts on the topic on this blog alone, but let me talk…
Those foam stripes parallel to the coast — again!
I think I might be getting obsessed with those stripes parallel to the coast. We saw them as foam stripes, eel grass stripes and now today: leaf stripes! Or should it…
Interference of one wave field with its reflection and a second wave field
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…
Wave-watching
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…
Wavelength dependency of wave-object-interactions
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…
Reflections on reflections
When we think about reflections in water, we usually think of calm lakes and trees on the shore opposite to us. Or clouds. Or at least that’s what I think…
Surface films dampen waves
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…
Foam stripes parallel to the coast, take 2
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…
Estimating volumes
Good thing laboratory equipment is always labeled with the volume! Even though I have played plenty with Legos as a child and am fairly good at 3D stuff, my mind…
The ocean really takes on the color of the sky
I guess it’s kinda obvious that the ocean always appears to be the color of the sky. On grey days, the ocean looks grey. If the sky is blue, so…
Swell and wind waves
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,…
Wavelets on bow wave
The other day (well, the other day when I was still at sea and wrote that blog post. Been quite a while since…), when sailing in calm waters, I noticed…
Moving sandbanks
A while ago I wrote a blog post on how the sand banks in this little creek form. Below you see the picture I showed then: Then, about two weeks…
Watch the dispersion relation in action
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…
Recovering an oceanographic mooring
So in my previous post we deployed a mooring (in fact, those pictures were from the deployment of several different moorings). Now how do we get such a monster back…
Deploying an oceanographic mooring
Do you want to know the full story behind the rope in the mystery picture the other day? On the recent Håkon Mosby cruise, we did a lot of mooring…
Reading the water – a new mystery picture for you!
Back by popular demand: Reading the water in my mystery pictures series! Who knows what’s going on in the picture below? You might recognize a couple of details that might…
Measuring the concentration of dissolved oxygen in sea water – Part 3 of 3 – finding the titration volume by looking at the change in color
So now we have prepared our sea water sample and are ready to start titrating to figure out the concentration of dissolved oxygen. The sample itself changes color with added…
Measuring the concentration of dissolved oxygen in sea water – Part 2 of 3 – the measuring part
So how do we actually measure dissolved oxygen concentrations from the samples we took in the last post? We are using a method called “titration” to determine the unknown concentration…
Measuring the concentration of dissolved oxygen in sea water – Part 1 of 3 – taking samples
Since my task on the recent Håkon Mosby cruise was to measure dissolved oxygen, I will give an overview over how that is done over the next couple of posts.…
Joys of a sea-going oceanographer
So you might have noticed that the last 6 weeks or so all posts had been scheduled ahead and that I was strangely absent. Yep. That’s because I was on…
Bubbles and the sun
One thing that I always notice but that is really difficult to take pictures of: How bubbles on a water surface focus the light into little stars on the ground.…
Awesome wake of high speed catamaran
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…
Erosion
Erosion happens not only to sandy paths or beaches on the large scale, but also on a small scale to really sturdy structures like the groynes in Hastings, where each…
Tides
Another thing I can’t stop being fascinated by: Tides. Sometimes you look towards Hastings Pier, and there is water all the way up to the sea wall. Those are the…
Standing waves
One thing I find endlessly fascinating are – you might have heard it before – standing waves. At the waterfront in Kiel I saw some the other day: Watch the movie…
Waves transport energy, but not mass
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…
Waves break when they reach a critical steepness
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…
Waves change their direction because of changes in water depth
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…
How water changes coast lines
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…
The enormity of waves
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…
Waves in the clouds
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 building of sand banks
The eroding force of moving water can be seen in so many places when you pay attention. For example in a park where I sometimes go for walks, the really…
2nd harmonic oscillation of a rope full with balloons — and announcing a summer break
On one of my very last days in my old job, I walked across campus and noticed this: I had to, of course, alert all my nearby friends! Especially since, on…
Shadows of condensation trails (aka “cirrus aviaticus”)
It wouldn’t be surprising at all to hear that if a cloud moves in front of the sun, a shadow appears on the ground. But I recently observed pretty much…
Front-spotting in muddy waters
On a recent flight from Hamburg to London City Airport, I ended up on one of the tiniest planes I’ve ever been on. Which meant that we flew super low,…
Frost flowers on ice cream: When you start thinking about phenomena and something really annoying, all of a sudden, becomes really cool.
Frost flowers on ice cream. You must have seen them before: They sometimes occur when you’ve had some ice cream, put the left-overs back in the freezer, and take them out…
Another wave hunt expedition: Learning to discover ocean physics wherever you go
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…
Learning about tides from art moored in a river
Disclaimer: This post might well be called “fun with tides” similar to Sheldon Cooper’s “fun with flags” — it is super nerdy, but at least I am having fun! There…
Why waves propagate so slowly into smooth patches of water
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…
Observe a fresh water layer (with your eyes, not a CTD!)
Sometimes you actually see fresh water layers (see with your eyes, not a CTD or some other instrument) floating on top of denser waters, not only in your kitchen and…
Foam stripes parallel to the coast.
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…
Looking at how waves are bent
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…
More wave-spotting in “urban environments”
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…
Walking around a lake to look at waves from all sides
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…
Ships sailing through trees
Ships sailing through trees? What? The other day I went on a trip to Husum with my sister and her family. While walking along the sea, we saw the weirdest…
Diffraction and reflection of waves
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…
Foam stripes on the water.
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…
Rain on water — why does each raindrop cause several concentric waves?
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,…
Taking the hydrostatic paradox to the next (water) level
How well do people understand hydrostatics? I am preparing a workshop for tomorrow night and I am getting very bored by the questions that I have been using to introduce…
A string of bubbles
Have you ever noticed champagne bubbles that form as a string right in the middle of the glass and hardly anywhere else? This leads to the very cool pattern you…
This *hic* is your captain spea*hic*ing. Spectacular condensation trails!
One day last year I spotted the weirdest thing from my office window: A condensation trail of a plane whose captain clearly had the hiccups. See for yourself: Have a closer…
Refraction of light in water
How deep is the pool? Really looks like it is super flat, doesn’t it? It’s not, it’s almost shoulder-deep (if you aren’t taller than me ;-)) Even though I’ve known about…
More wave phenomena on a lake, and a bit about wind
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…
Wave hunt expedition. You don’t need to live close to the coast to observe all kinds of wave phenomena!
A 1.5 hour walk around a lake — and 242 photos of said lake — later I can tell you one thing: You definitely don’t need to live close to…
One of the most exciting things about work travel?
One of the most exciting things about work travel? Staying in tons of different hotels, which all have different opportunities to play with water. For example at a recent team…
Observing hydrodynamics on a very large scale
You know I like to point out where you can spot hydrodynamics concepts in your everyday lives (at least if your everyday lives include strolls along rivers and generally a…
Observing hydrodynamic phenomena on a creek
Looking at a creek on a Sunday stroll, and seeing lots and lots of concepts from hydrodynamics class. For example below, you see waves radiating from each of the ducks. And…
Frost flowers – when water vapour freezes to ice without going through the liquid phase. Examples “at sea”
Frost flowers! I learned about those in the context of Arctic and Antarctic ice formation. I kinda assumed that ice flowers only formed in salt water, because I remember hearing about…
Frost flowers – when water vapour freezes to ice without going through the liquid phase. Examples on land
What happens when water vapour freezes to ice without going through the liquid phase? Frost flowers!!! That’s when trees suddenly look like this: Btw – the stem of that tree…
Using the period of a swinging lamp to calculate the height of the ceiling
Using the period of a swinging lamp to calculate the height of the ceiling. When, on December 31st of last year, I was sitting in church on the gallery, listening…
Reading ice on a river as tracer for flow fields
For most of my readers it might be pretty obvious what the movement of floating ice says about the flow field “below”, but most “normal” people would probably not even notice that…
Using a shadow to estimate the date a photo was taken
This post might be a bit nerdy, but at least it runs in the family: My dad was recently trying to find out when this photo inside a church had been…
Submerged hydraulic jump – observing hydrodynamic phenomena in real life
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…
Jan Mayen picture dump
I’ve been thinking about that one research cruise in 2012 (Cruise webpage: “Greenland’s frozen coast”) where we passed Jan Mayen and had the chance to see the amazing coast line…
Why does the sun have to be a lot further from us than the moon? A deduction.
Remember the hands-on demo of the phase of the moon? Holding a sphere up in the sunlight in the direction of the moon, the sphere will show the same phase…
Watch how the sun is moving
This is another example for deducing that the sun is moving because its shadow must have moved to thaw a roof in a certain way: Thanks, mom!
As frost starts melting, and the roof is getting dry, oh! The sun is up.
My office looks out directly onto the roof of our main lecture theatre, and it is fascinating how much you can observe just by looking out of a window and onto…
Granular convection
What is wrong with this picture? Don’t you guys make your parents stop the car when you drive by newly built walls in random villages somewhere when they are a…
The difference between secondary rainbows and double rainbows
More reflection or more rain? Ha, aren’t you enjoying talking about optics again? Sometimes you see two rainbows that both have red on the outside and blue on the inside.…
Sun dogs
Recently spotted: sun dogs, a special form of halo! Or rather sun dog (singular), since there was only one to be seen and not a second one at equal distance…
Raindrops on water
I’ve been trying to take good pictures of drops falling on water for a while now, but somehow it always ends up meh-ish. These kind of situations look so pretty…
Why is the bottom of the other shoreline cut off?
My dad keeps asking me about a claim I made in my post about the curvature of the Earth: That looking at sea level across a 500 m wide part…
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…
Amplifying waves
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…
Waves on a slope
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 –…
Fetch and wind waves
Summer holidays in beautiful Cornwall – what more can you ask for? If only these pictures weren’t from last year… Anyway, one can dream. And one can find awesome oceanography…
Reading the water
Let’s play another game of “reading the water“. This is a picture that my dad sent me. Can you see what is going on there?
Waterfalls
You saw the waterfall in my post two days ago already, when I talked about continuity. But now let’s take a closer look. Obviously, it’s artificial, but that makes for…
Continuity
Last week I went to beautiful Lüneburg with a group of climate scientists to continue working on a very exciting project I’ve been involved in over the last year or…
Interference of waves
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…
Creating eddies
I always love watching paddles in water, or ships in water, or ducks in water, or anything water, really, but on a wind-less day in Ratzeburg, Siska managed to create…
Curvature of the Earth
In Ratzeburg, we very much enjoyed our daily early morning swims. One thing that is really nice to observe when you are swimming in a calm lake is how things…
Oh so this is what the water level usually looks like around here!
Do you know how, on sea walls, you can see what a typical water level is by the kind of gunk that is growing on the wall in horizontal lines?…
Pinging, so we don’t hit the ground
I’ve been thinking about an old friends recently. I met Anton on a RV Knorr-cruise I was on in 2011, and we spent many fun night watches running CTDs. Together with…
Rainbows and prisms
Lets go back and talk about one of my favorite non-oceanographic topics: Rainbows! When I had my rainbow phase about a year ago, my mom sent me the movie below, which shows what…
Duck trajectories
I’m sure I’ve talked about stream lines and streak lines and all the other kinds of lines that you learn about in hydrodynamics at some point. The other day I saw…
Diving ducky and resulting eddies
My sister and I did a little sight-seeing tour in Hamburg the other day, and one of the most fascinating things I saw was — a diving duck. Now, that is…
Cloud waves – wave clouds
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…
Phase of the moon
Relating the phases of the moon to one side of the moon being lit by the sun and the other side being in the dark sometimes appears a bit unintuitive. One thing…
Shear flow
Another early morning crossing this bridge. And the current and the sun glint were perfect for this kind of photos:They almost look like schlieren photography images in those super old papers,…
Weird algae stripes
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…
Streak lines?
A common problem in hydrodynamics is to distinguish between all the different kinds of lines that characterize a flow field: Stream lines, streak lines, path lines, time lines, and probably…
Refraction of waves
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…
Reading the water
As you might know, I really enjoy reading the water – watching the water trying to figure out what processes caused the patterns I see. So here are two more movies…
Thank you, Archimedes!
I really like hydrostatics. Of course I like moving water even better, but even static water is great. And there are so many things to explore! If I was to…
Ship lift Scharnebeck
Today I’m going to share a long movie with you, but I’m planning to talk about ship lifts in more detail soon. But just how awesome is it that they…
Waves radiating from an object
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…
Flow separation
On the way to the pool I cross over the Elbe river on this pretty bridge. Which is pretty spectacular, just because the structure itself is so amazing. But what…
Eddy generation and optics.
Eddies. Dips in the surface and shadows on the ground. I always get really fascinated by watching how eddies are generated by obstacles in a fluid. But it is especially…
Waves on a current
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…
Currents caused by thrusters
Or: fast inflow into nearly stagnant water body Did you ever notice how when certain ferries dock, they stop, already parallel to the dock, a couple of meters away from…
Thermoplastic ketchup bottles
After all those text-heavy posts this week, here is something that really fascinated me recently. I had an empty ketchup bottle lying in my sink when I strained some pasta.…
Watching the solar eclipse using “household items”
Different methods to project the sun to watch it safely. During our recent PBL workshop, we came up with a number of different ways to watch a solar eclipse by…
Solar projector
In preparation of our solar eclipse PBL workshop, my parents came to play. And they brought the Astromedia solar projector cardboard kit! It took us the better part of a day…
Drops and a pool
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…
How the shape of your bow can save you a lot of time and money
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…
Vortex street
Do you use a tide chart to find the best time for your Saturday walk, too? I showed you a vortex street on a plate formed by pulling a paint brush through sugary…
Confluence of Danube and Morava river
Confluence of Danube and Morava river. Watching the shear flow on Elbe river the other day, I was reminded of another shear flow which I had watched a long time…
Shear flow
Kelvin-Helmholtz instabilities in a shear flow in Elbe river. Last week I talked about how I wanted to use the “Elbe” model in teaching. Here is another idea for an exercise: On…
Centrifugal governor
One of the advantages of working at a university: You always find people who enjoy playing :-) Last summer, I visited the ThinkTank museum in Birmingham. I already posted about…
Continuity
What do you see when you look at an aquarium? When I was in Gothenburg last year for EMSEA14, one night we got to hang out at the Sjöfartsmuseet Akvariet there,…
Simple pendulum
Because physics is everywhere! Happy New Year, everybody! Hope you all had a good break and are excited to start lots of exciting projects in 2015! One project I will definitely…
Diffraction of light
Today I’m playing with the sun. As I mentioned in the sun dog post already, I recently went on the ferry from Kiel to Gothenburg. And I had plenty of…
Tidal elevations and currents in Fowey, Cornwall
Tides in Cornwall. The other day we talked about a very simplistic models of tides in a glass, and how the high tide and low tide travel as a wave…
Sun dogs
More refraction of light. Recently I found myself on the ferry from Kiel to Gothenburg, watching the sun rise. Next to the sun, I noticed a piece of a rainbow.…
Awesome fountain Birmingham
Because water is endlessly fascinating. As those of you who know me in person are acutely aware – I am traveling too much right now. Hence the content on this…
Trajectories of a projectile
And you know me – it had to be a projectile made of water. The shopping mall where I live has some really nice water features that I always get…
Lighthouses and Fresnel lenses
Or more reasons for why I want to live in a lighthouse. I have always been fascinated by lighthouses. Always. Usually because they are built in the most wonderful places…
What are the ingredients of a rainbow?
Still collecting materials for our instructional short movies. A while back I talked about how my colleague and I were experimenting with short instructional screen casts, and I shared some…
Why do we only see rainbows in the mornings and evenings, but never at noon?
Another movie on rainbows My dearest readers, I hope you are still as fascinated by rainbows as I am? Today I’m giving you another movie explaining something rainbow-related, namely why…
Rainbows III
Updated movie following Arne’s advice. When I asked for feedback on the rainbow movies the other day, Arne had a pretty good idea for how one of the explanations could…
Sun halo
A rainbow that isn’t one, technically speaking. Browsing through the photos on my phone, I came across the one below that I took two years ago in Bergen. I remember taking…
Help! Weird ice crystals
Geli, Torge, and all you other ice people – do you know what this is? Browsing pictures on my phone, I came across the pictures below that I took a…
Guest post: Arctic sea ice thinning.
Exciting guest post on a newly published paper by Angelika H. H. Renner. I’ve met Angelika on a cruise in the Antarctic Circumpolar Current a long time ago where we worked…
Tidal currents at Saltstraumen.
Watching the strongest tidal current in the world. Together with my friend P, I went to see the strongest tidal current in the world more than two years ago. And…
Guest post: The 5-minute warning of a summer’s day sudden end.
More bad weather in Hamburg. Today I have the pleasure to announce a guest post by Torge Martin. Torge, together with J&J, came to visit Hamburg recently, and we got…
Surface tension and office supplies.
Lots of stuff an be made to float on water just because of surface tension. This morning, I was taking pictures of heaps of waters on coins. I was planning to…
Surface tension – heaps of water.
The classical way of demonstrating surface tension. When talking about surface tension, the classical thing to do is to talk about the shape of drops of water. As seen before…
Surface tension and water striders
How water striders can walk on water. More pictures from the same spot at the banks of the Pinnau. Looking more closely, you can see the water strider: And now…
Refraction of light in water – sticks and lenses.
Deformation in the water surface focussing light. Talking about how a deformation in the surface leads to light being focussed in different ways here and here, another example came to…
Eddies – surface imprint and optical properties
You can see “shadows” of eddies on the ground! As everybody who has ever watched a bath tub drain knows – eddies do lead to a deformation of the water’s surface.…
Refraction of light in water – coins and lenses.
More on what water can do to light. Remember my fascination with dandelions? Just to remind you: Especially in combination with coins and water droplets, dandelions are a source of…
Refraction of light in water.
What water can do to light. In the last post, I showed you a couple of pictures of a vase filled with dandelions. Turns out this might not have been enough of…
Standing waves
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…
Wake of a house.
Am I weird for noticing that kind of stuff? When I posted that picture of the fountain in the last post, it very strongly reminded me of a breakfast my sister and I…
Wind shear.
Wind going in different directions at different heights. Apparently some people were intrigued by the white mist they saw on the last picture in my last post (below). First, let…
Reading the water
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…
Lava
Don’t you just love lava lamps? I got a lot of weird looks when I excitedly told people about two years ago that I had just bought a lava lamp.…
Wind waves meet current
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,…
Advection fog
When warm, moist air is advected and brought in contact with colder surfaces. Recently I’ve been starting to think about a course I’ll be teaching later this year, and how…
Hydraulic jump II
More movies of my kitchen sink. I am really fascinated by the hydraulic jumps in my kitchen sink. I can’t believe I haven’t used this before when I was teaching!…
Hydraulic jumps
Water changing its velocity from above to below the critical velocity. Recently in beautiful Wetzlar: The river Lahn flows through the city below the medieval cathedral at sunset. And I’m…
Waves being deflected towards regions of lower phase velocity
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…
Langmuir circulation
We think we observed Langmuir circulation, but we don’t understand the mechanism causing it. Recently, my friend Leela came to visit Bergen and we went on a fjord cruise to…
Types of breaking waves depending on steepness of slope – small scale
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…
Waves breaking depending on steepness of the slope
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…
Mid-Atlantic Ridge
The Mid-Atlantic Ridge above sea level in Iceland. On my recent trip to Iceland, I had to seize the opportunity to take pictures of plate tectonics at work. Imagining oceanic…
Geysers
Photos and movies from geysers on Iceland. I already talked about hydrothermal activity in this post. But then after writing it, we went and did the golden circle tour and…
Hydrothermal springs
Hydrothermal springs that you can visit without a deep-sea submersible. When teaching about hydrothermal springs, I usually use a video a friend of mine took of hydrothermal vents on the…
Interference of waves.
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…
Early stages of ice formation
Some photos to illustrate the early stages of ice formation. When I was showing my ice formation pictures the other day (also in this post), I realized that even though…
Internal waves in the atmosphere
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.…
Ice in the ocean – my historical photos
Ice formation in the ocean – using my own photos to tell the story. Recently I talked about using my own photo to explain the generation of wind-generated waves to…