Category Archives: kitchen oceanography

#KitchenOceanography as #FieldWorkFix

This is the longer version of the (A4!) poster that I am presenting on behalf of myself, Kjersti Daae, Elin Darelius, Joke Lübbecke and Torge Martin at the #FieldWorkFix conference next Tuesday (September 8, 2020). If you would rather listen to the voiceover than read the transcript below, please feel free to do that below! (Thanks to Torge, the voice over is about 1/3rd the length of the blogpost that I originally wrote to use as script :-D)

#KitchenOceanography: Bringing physical oceanography into students’ homes

Welcome to our virtual poster! I want to tell you about #KitchenOceanography: experiments that students can do at home, using common household items. Whether due to Covid-19, or institutional constraints like the lack of laboratory spaces or instructors, or simply because a hands-on experience would be useful with a certain concept, but it’s not on the syllabus – #KitchenOceanography is a great substitute for doing experiments in a laboratory course when that isn’t possible.

We use #KitchenOceanography when teaching physical oceanography and climate sciences. But the concept of home experiments can easily be transferred to other fields, and I therefore want to present the learning outcomes we can achieve on a fairly abstract level. If you would like to learn about #KitchenOceanography experiments in detail rather than just the general concept which I am presenting here, please follow the link on our poster to a blog post in which I have linked to tons of examples of different learning outcomes and experiments (and to all the experiments mentioned here, as well as 24 easy starter experiments).

One typical learning outcome in laboratory courses is the deepening of understanding of concepts that are theoretically dealt with in a lecture. If the concept itself cannot easily, affordably or safely be transformed into a home experiment, you could ask students to come up with a demonstration of an analogy with the concept instead. We have done that when teaching about processes that govern the El-Niño-Southern-Oscillationpattern in the Pacific Ocean. Of course, students cannot build a physical model that represents all the processes in the ocean and atmosphere that are relevant, but they can come up with demonstrations that show analogies of the cycle.

Another learning outcome in a laboratory might be developing intuition on the one hand, but also checking intuition against observations and explaining counterintuitive results. A great experiment here is to ask students to place ice cubes in two beakers with room-temperature water, one salt water and one freshwater. Asking students to predict which of the ice cubes will melt faster leads to 90% wrong predictions, and because it is really difficult to come to terms with a wrong intuition, it will lead to a lot of learning around experimental skills. Students will ask themselves if they maybe accidentally swapped the beakers because they didn’t take notes of which one was which. They might try to taste the water to test which of the beakers contains salt water (tasting in a lab of course being a big no-no). Even if the course is on a subject that is not related to ocean physics at all, this experiment still holds a huge potential to practice – and gaining appreciation for – laboratory skills.

A third common learning outcome in laboratory courses is for students to exercise curiosity and practice creativity. Using an experiment like the melting ice cubes one I just described ALWAYS works to do just that. Students will always come up with questions that they want to investigate. What would happen if the ice cubes weren’t floating in the water, but were forced down to the bottom of the beaker? Or if the ice cubes weren’t frozen fresh water, but had been made from salt water? In my experience, even students from other subjects that rolled their eyes when I told them they were going to do an experiment with water and ice in plastic cups get hooked and want to understand why their intuition was wrong and what more there is to explore.

Another learning outcome often connected to laboratory courses is to develop reporting skills. With the ice cube experiment I already showed the importance of taking notes even when experimenting only in your kitchen, and #KitchenOceanography lends itself to practicing writing lab reports: now many of the materials and conditions need to be described in a lot more detail because the cooking salt that I use in my kitchen might not have the same composition as the one that you are using, which might be kosher, or enriched in iodine, or reduced in sodium. So if we want to be able to compare results later on, all these things need to be written down. And of course, reporting skills might take a different form than a conventional lab report, especially when students are socially isolated, using for example social media or blogs as an outlet might provide them with community, feedback and recognition.

Lastly, a common learning outcome is to recognize problems and errors during experimentation. Since #KitchenOceanography is less supervised than a typical laboratory class, students will inevitably trouble-shoot more independently, and it’s a good idea to explicitly include reflection on what went wrong and how it was fixed in both documentation and discussion of the experiments.

So what would it look like to use #KitchenOceanography as #FieldWorkFix?

We have run #KitchenOceanography experiments in different instructional settings. Back in the day when we were still teaching in-person classes, in addition to using them as hands-on experiments within class, we gave them as homework. One task was to find a way to measure the salinity of a water sample the students were given, and came up with many surprising and creative solutions. In this setting, #KitchenOceanography was already done asynchronous: students did the experimental work whenever it suited them and report back. It can be done in exactly the same way, and reporting back can happen either in writing or in the class’ video call.

What we have had a lot of success with last semester, though, was a synchronous setup. In a video call, students did simplified versions of an experiment, and the instructor showed the full version of the experiment that students would have run in class, had that been possible. In our case, the experiments would ideally have been conducted on a rotating table to simulate Earth’s rotation. And while I have one in my home, not many students do. So we asked students to do the non-rotating version at home, while I presented the rotating version. The added benefit was that we took time to compare and contrast the two different versions and were thus able to isolate the effects of Earth’s rotation – something we would not have spent time on had students had the opportunity to work hands-on with the rotating tables themselves.

We had three modes of presenting the “full” version of the experiment: using pre-recorded videos (which is definitely the more error-proof way to do it!), running the experiments as a demonstration in real time, or asking students to “remotely control” me doing the experiment by telling me what parameters to modify to which values. This worked by me joining the video call with two devices: One that was recording myself and my experimental setup, looking into the tank from the side, and one that was mounted above the experimental setup and showed the top view (which was relevant for the experiment we were doing). Students shared their experiments via video stream when they chose to. The class was taught by a second instructor, which is what we would definitely recommend: Having one person host the meeting and deal with questions and difficulties as they arise, and have a second person focus on doing the experiment.

All in all, despite the unavoidable tech problems, doing these video conferences where we all did experiments together, were a lot of fun for all involved, and definitely helped make the somewhat sad and lonely experience of learning alone at home, instead of hands-on with a nice group of people, less lonely and a lot more fun.

Thank you for your attention.

A scicomm comic on Rossby waves and hands-on teaching

Last year in pre-social distancing times, Torge and I brought hands-on rotating tank experiments into his “atmosphere and ocean dynamics” class. The “dry theory to juicy reality” project was a lot of fun — the affordable DIYnamics rotating tables are great to give students hands-on experiences in small groups and to see — by running the same experiment on four rotating tables in parallel — how the same experimental setup can lead to very different realizations because of tiny differences in boundary conditions.

Instead of a classical lab report, we asked students to write a pupular science text about an experiment of their choosing. We got lots of great results (see all of them on our blog “Teaching Ocean Science“), but there is one that particularly stood out to me, and the author, Johanna Knauf, kindly agreed to me publishing it here. Enjoy!


I am super impressed with this comic, and also increadibly flattered and touched. This comic is the most meaningful feedback on my teaching and science communication I ever got and that I can possibly imagine. Thank you, Johanna!

P.S.: Curious about how we modified the project to work with social distancing? Check it out here!

Tilting frontal surface under rotation / cylinder collapse

Torge and I are planning to run the “tilting of a frontal surface under rotation / cylinder collapse” experiment as “remote kitchen oceanography” in his class on Thursday, so I’ve been practicing it today. It didn’t work out quite as well as it did when Pierre and I were running it in Bergen years ago, so if you are looking for my best movie of that experiment, you should go read the old blog post.

The idea is that a density front is set up by spinning up a tank in which a bottom-less cylinder contains a denser fluid, set up into a less dense fluid. Once the tank is spun up, the cylinder is removed, releasing the denser fluid into the less dense one. In contrast to the non-rotating case, where the dense water would sink to the bottom of the tank and form a layer underneath the less dense water, here the cylinder changes its shape to form a cone that retains its shape. The slope of the front is determined by both the rotation rate and the density contrast.

What I can show you today is what it looks like on my DIYnamics rotating table in my kitchen (and it’s pretty cool that all these different experiments can be run on such a simple setup, isn’t it?!). This is from two weeks ago:

And a second attempt done today (I’m not showing you all the failed ones in between, and since I’m a little sick, I’m also not showing you what I look like, and spare you the sound of my incoherend explanations ;-)). But: Now everything is set up so I can use my right hand to pull out the cylinder to introduce fewer disturbances (spoiler alert: didn’t work out — see all the waves on the tank after I remove the cylinder?)

Check out the flower “floats” — the ones on the remains of the cylinder are rotating in the same direction as the tank, only faster! That’s something we didn’t show in Bergen and that I think is really neat.

What I learned about how to set up the experiment: I filled the cylinder with ice cubes and then filled water into the donut outside of the cylinder. That way, water pressure would push water through the petroleum jelly seal at the bottom of the cylinder inside, but the dye of the melting ice cubes would not seep out (very much). Also, the cold melt water would make the water inside the cylinder denser (make sure to stir!). The whole fancy “get water out and refill using a syringe” stuff sounds nice but just isn’t feasible in my setup…

In this case, having a larger tank would be really helpful, because the disturbances introduced in either case are probably more or less the same, but the smaller the tank, the larger the relative effect of a disturbance… Also, my tripod was making it really difficult for me to reach into the tank without hitting it, both for filling the tank and for removing the cylinder. I guess if we didn’t need a top view, things would be a lot easier… ;-)

Rotating vs non-rotating turbulence

Last Thursday, Torge & I invited his “atmosphere & ocean dynamics class” to a virtual excursion into my kitchen — to do some cool experiments. As you know, I have the DIYnamics rotating table setup at home, so this is what it looked like:

We did two experiments, the very boring (but very important) solid body rotation, and then the much more exciting (and quite pretty, see pic at the very top or movie below!) comparison of turbulence in a non-rotating and a rotating system.

We didn’t manage to record the class as we had planned, so I redid & recorded the experiments. Here are 8 minutes of me talking you through it. Enjoy!

A common misconception in rotating tank experiments, and one way of maybe not reinforcing it

A very common misconception when looking at atmosphere & ocean dynamics in a rotating tank is that the center of the tank represents one of the poles and the edge of the tank the equator. And there is one experiment that — I fear — might reinforce that misconception, and that is the one we love to show for rotation vs thermal forcing, baroclinic instabilities (fast
rotation), Hadley cell circulation (slow rotation).

When we do this experiment, the tank looks like a polar stereographic view of the Earth, with the pole (represented by the blue ice in the picture below) in the center and the equator at the edge of the tank. And when we then talk about the eddies we see as representing weather pattern, it’s all too easy to assume that the Coriolis parameter also varies throughout the tank similarly as it would on Earth, only projected down into the tank. Which is not the case!

But the good news is that it’s super easy to drive this experiment by heating rather than cooling in the center of the tank. The physics are exactly the same, only the heat transport is now happening radially outward rather than radially inward. And that it’s now not the easiest assumption any more that we are looking down at the pole.

Also: Heating in the middle is a lot easier to do spontaneously than cooling using ice — no overnight stay in the fridge required, just a kettle! :-)

What are other misconceptions related to rotating tanks that you commonly come across? And do you have any advice on how to prevent these misconceptions or elicit, confront, resolve them?

Thermal forcing vs rotation tank experiments in more detail than you ever wanted to know

This is the long version of the two full “low latitude, laminar, tropical Hadley circulation” and “baroclinic instability, eddying, extra-tropical circulation” experiments. A much shorter version (that also includes the end cases “no rotation” and “no thermal forcing”) can be found here.

Several of my friends were planning on teaching with DIYnamics rotating tables right now. Unfortunately, that’s currently impossible. Fortunately, though, I have one at home and enjoy playing with it enough that I’m

  1. Playing with it
  2. Making videos of me playing with it
  3. Putting the videos on the internet
  4. Going to do video calls with my friends’ classes, so that the students can at least “remote control” the hands-on experiments they were supposed to be doing themselves.

Here is me introducing the setup:

Today, I want to share a video I filmed on thermal forcing vs rotation. To be clear: This is not a polished, stand-alone teaching video. It’s me rambling while playing. It’s supposed to give students an initial idea of an experiment we’ll be doing together during a video call, and that they’ll be discussing in much more depth in class. It’s also meant to prepare them for more “polished” videos, which are sometimes so polished that it’s hard to actually see what’s going on. If everything looks too perfect it almost looks unreal, know what I mean? Anyway, this is as authentic as it gets, me playing in my kitchen. Welcome! :-)

In the video, I am showing the two full experiments: For small rotations we get a low latitude, laminar, tropical Hadley circulation case. Spinning faster, we get a baroclinic instability, eddying, extra-tropical case. And as you’ll see, I didn’t know which circulation I was going to get beforehand, because I didn’t do the maths before running it. I like surprises, and luckily it worked out well!

Thermal forcing vs rotation

The first experiment we ever ran with our DIYnamics rotating tank was using a cold beer bottle in the center of a rotating tank full or lukewarm water. This experiment is really interesting because, depending on the rotation of the tank, it will display different regimes. For small rotations we get a low latitude, laminar, tropical Hadley circulation case. Spinning faster, we get a baroclinic instability, eddying, extra-tropical case. Both are really interesting, and in the movie below I am showing four experimentsm ranging from “thermal forcing, no rotation”, over two experiments which include both thermal forcing and rotation at different rates to show both the “Hadley cell” and “baroclinic instability” case, to “no thermal forcing, just rotation”. Enjoy!

Ekman layers in my kitchen

Several of my friends were planning on teaching with DIYnamics rotating tables right now. Unfortunately, that’s currently impossible. Fortunately, though, I have one at home and enjoy playing with it enough that I’m

  1. Playing with it
  2. Making videos of me playing with it
  3. Putting the videos on the internet
  4. Going to do video calls with my friends’ classes, so that the students can at least “remote control” the hands-on experiments they were supposed to be doing themselves.

Here is me introducing the setup:

Today, I want to share a video I filmed on Ekman layers. To be clear: This is not a polished, stand-alone teaching video. It’s me rambling while playing. It’s supposed to give students an initial idea of an experiment we’ll be doing together during a video call, and that they’ll be discussing in much more depth in class. It’s also meant to prepare them for more “polished” videos, which are sometimes so polished that it’s hard to actually see what’s going on. If everything looks too perfect it almost looks unreal, know what I mean? Anyway, this is as authentic as it gets, me playing in my kitchen. Welcome! :-)

In the video, I am stopping a tank that was spun up into solid body rotation, to watch a bottom Ekman layer develop. Follow along for the whole journey:

Now. What are you curious about? What would you like to try? What would you do differently? Any questions for me? :-)

Rossby-#WaveWatchingWednesday

Several of my friends were planning on teaching with DIYnamics rotating tables right now. Unfortunately, that’s currently impossible. Fortunately, though, I have one at home and enjoy playing with it enough that I’m

  1. Playing with it
  2. Making videos of me playing with it
  3. Putting the videos on the internet
  4. Going to do video calls with my friends’ classes, so that the students can at least “remote control” the hands-on experiments they were supposed to be doing themselves.

Here is me introducing the setup:

Today, I want to share a video I filmed on planetary Rossby waves. To be clear: This is not a polished, stand-alone teaching video. It’s me rambling while playing. It’s supposed to give students an initial idea of an experiment we’ll be doing together during a video call, and that they’ll be discussing in much more depth in class. It’s also meant to prepare them for more “polished” videos, which are sometimes so polished that it’s hard to actually see what’s going on. If everything looks too perfect it almost looks artificial, know what I mean? Anyway, this is as authentic as it gets, me playing in my kitchen. Welcome! :-)

In the video, I am using an ice cube, melting on a sloping bottom in a rotating tank, to create planetary Rossby waves. Follow along with the whole process:

Also check out the video below that shows both a top- and side view of a planetary Rossby wave, both filmed with co-rotating cameras.

Previous blog posts with more movies for example here.

Now. What are you curious about? What would you like to try? What would you do differently? Any questions for me? :-)

Brine rejection and overturning, but not the way you think! Guest post by Robert Dellinger

It’s #KitchenOceanography season! For example in Prof. Tessa M Hill‘s class at UC Davis. Last week, her student Robert Dellinger posted a video of an overturning circulation on Twitter that got me super excited (not only because as of now, April 15th, it has 70 retweets and 309 likes. That’s orders of magnitude more successful than any kitchen oceanography stuff I have ever posted! Congratulations!).

Robert is using red, warm water on one side and melt water of blue ice cubes on the other side to provide heating and cooling to his tank to create the overturning. Why did I get so excited? Because of this: the head of the meltwater plume was very clearly not blue (see above)! Rob kindly agreed to write a guest post about these observations:

“I first and foremost want to start off by thanking Dr. Mirjam Glessmer for doing a phenomenal job at SciCom through Kitchen Oceanography. I was able to replicate her physical oceanography experiment regarding oceanic overturning circulation for my oceanography class with Dr. Tessa Hill.

As mentioned in her previous post, oceanographic currents are often simplified to give an easier understanding of how oceanic overturning circulation operates. The top 10% of our oceans are controlled by wind-driven currents and tidal fluctuations while the bottom 90% of our ocean currents are controlled by density-dependent movements.Originally this process was defined as thermal circulation but was later expanded to thermohaline circulation. Thermohaline circulation is dependent upon both temperature (thermal) and salinity (haline.) These density-dependent reactions occur when either freshwater fluxes meet saltwater and from thermal differences in water masses. Due to differential heating in our planet, colder formations of dense water masses are formed at the poles, which in turn causes the convective mixing and sinking of water masses driving oceanic circulation.

(Video by Robert Dellinger; thanks for letting me use it!)

In this experiment, we primarily focus on the thermally dependent reactions between two water masses. As seen in the video, the warmer water mass is dyed red, while the cold water mass formed by ice melting, is blue. As expected the more dense water mass (cold) is pushed under the warmer mass once they meet. One feature I would like to point out is the clear plume head feature in my experiment (see picture on top of this post). My theory is that part of the ice cube that was not dyed melted first and was pushed under the warm water mass. This feature is most likely due to the ice cube experiencing unequal cooling, which in turn led to an uneven dye distribution as seen in the previous post “Sea ice formation, brine release, or: What ice cubes can tell you about your freezer.

As seen in the experiment, thermohaline circulation is thermally driven therefore, the role of salinity causes the system to be non-linear. Salinity serves as a positive feedback mechanism by increasing the salinity of deeper water and strengthens the circulation. Furthermore, current studies are focusing on how atmospheric warming is altering thermohaline circulation attributed by increases in ocean heat absorption and freshwater fluxes (primarily from melting ice caps.)”