New SERC “Teach the Earth” Activity on “Ocean Currents and Overflows”
One day in the office at the Geophysical Institute in Bergen last Friday, and for the first time in a long time I am writing a little bit of oceanography…
Tag: density
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…
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…
Ice cubes melting in fresh water and salt water
Today we are doing the melting ice cubes experiment in fancy glasses, because Elin is giving a fancy lecture tonight: The Nansen Memorial Lecture of the Norwegian Science Academy in…
Demonstration: Nansen’s “dead water” in a tank!
A ship that is continuously pulled with a constant force suddenly slows down, stops, and then continues sailing as if nothing ever happened? What’s going on there? We will investigate…
Accidental double-diffusive mixing
When setting up the stratification for the Nansen “dead water” demo (that we’ll show later today, and until then I am not allowed to share any videos, sorry!), I went…
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…
The one where it would help to understand the theory better (but still: awesome tank experiment!)
The main reason why we went to all the trouble of setting up a quasi-continuous stratification to pull our mountain through instead of sticking to the 2 layer system we…
Dead water — the fancy experiment including Nansen himself
Now that we do have a really awesome 12-layer 6-color stratification, we obviously had to do the dead water experiment again. This time we chose to include a not-too-happy-looking Nansen…
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…
Experiment: Oceanic overturning circulation (the slightly more complicated version)
The experiment presented on this page is called the “slightly more complicated version” because it builds on the experiment “oceanic overturning circulation (the easiest version)” here. Background One of the…
Experiment: Influence of stratification on mixing
A wind stress is applied to the surface of a stratified and a non-stratified tank to cause mixing. This is a pretty impressive experiment to run if you have a…
Melting ice cubes experiment — observing the finer details
If you don’t know my favourite experiment for practically all purposes yet (Introduction to experimenting? Check! Thermohaline circulation? Check! Lab safety? Check! Scientific process? Check! And the list goes on…
About neutrally buoyant particles, popcorn, and more bubbles
When you see all our pretty images of currents and swirling eddies and everything, what you actually see are the neutrally buoyant particles that get lit by the laser in…
Melting ice cubes & thermal imaging camera
I haven’t talked about my favourite experiment in a long time (before using it last week in the MeerKlima congress and suddenly talking about it all the time again), because I…
Workshop prep and a riddle
Looking at the picture below, can you guess which experiment I am going to do at the MeerKlima.de workshop? Yep, my favourite experiment — melting ice cubes! :-) And I am…
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…
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…
Why moist air is lighter than dry air.
Why is moist air lighter than dry air? This seems pretty counter-intuitive at first, but then really isn’t. I promised to do a post on why moist air is lighter…
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…
Using the “melting ice cube” experiment to let future instructors experience inquiry-based learning.
Using the “melting ice cube” experiment to let future instructors experience inquiry-based learning. I recently (well, last year, but you know…) got the chance to fill in for a colleague…
The importance of playing in outreach activities.
Some time ago, I wrote two blog posts on the importance of playing in outreach activities for the EGU’s blog’s “educational corner” GeoEd. Both have now been published, check them…
When water doesn’t seek its level
Last week we talked about misconceptions related to hydrostatic pressure, and how water always seeks its level. Today I’m gonna show you circumstances in which this is actually not the…
My favorite demonstration of the coolest mixing process: Salt fingering!
I am updating many of my old posts on experiments and combining multiple posts on the same topic to come up with a state-of-the-art post, so you can always find the…
A very simple overturning experiment for outreach and teaching
For one of my side-projects I needed higher-resolution photos of the overturning experiment, so I had to redo it. Figured I’d share them with you, too. You know the experiment: gel…
On buoyancy
This is an experiment that Martin brought to Ratzeburg and that he let me use on my blog: Using a beam balance to talk about buoyancy. So at first we…
When diet coke cans don’t float better than regular coke cans
This is why you should always test an experiment before you run it… On recent travels, when I saw that they were serving drinks out of tiny cans, I asked…
“Isostasy” of ships
Empty ships look weird. Since we talked about the ship-and-anchor thing last week (you know – what happens to the water level when an anchor that was previously stored…
Which displaces more water, a boat with the anchor onboard or in the water?
Not that this is a big effect in the ocean, but still, it’s a nice demo. A body submerges into the water until it displaces an amount of water that is…
Ice cubes melting at the bottom of the beakers
Because surely there is one more post in this topic? ;-) For those of you who haven’t heard about the “melting ice cube” obsession of mine, please check out the…
Why folic acid might be good for people, but not so good for tank experiments
I had to do the complete series of experiments, of course… The other day I mentioned that I had used salt from my kitchen for the “ice cubes melting in…
Melting ice cubes, again
Somehow I am stuck on this demonstration! I can’t let go of this experiment. Last time I posted about it, someone (Hallo Papa!) complained about the background and how I…
Conducting experiments at EMSEA14
Kristin’s and my workshop at EMSEA14. As I mentioned before, Kristin Richter and I are running the workshop “Conducting oceanographic experiments in a conventional classroom anywhere” at the European Marine Science…
The icy elevator
Weird things happening when ice cubes melt. Remember I said that there were weird and wonderful things going on when I last ran the melting ice cubes in salt and…
Melting ice cubes reloaded
Or why you should pay attention to the kind of salt you use for your experiments. The melting ice cubes in salt and fresh water is one of my favorites that…
Learning with fluid toys
How fluid toys can be used to demonstrate principles of fluid mechanics. I guess every attempt to hide that I LOOOOVE fluid toys of any kind is futile. So imagine…
The effects of rotation on a collapsing column
Comparing a rotating and non-rotating dipole. I just realized that I never explicitly showed the difference between rotation and no rotation, even though I do have the footage to do so:…
Simulations of hetonic explosions
Because sometimes it’s easier to control a computer than rotation, salinity, water and dye. After looking at a non-rotating cylinder collapse the other day, it is time to look at…
Collapsing column
Or: This is what happens to a hetonic explosion experiment without rotation. I’ve posted a lot while at JuniorAkademie a while back, so it is hard to believe there are still experiments…
Double overflow
Because sometimes one overflow simply isn’t enough. Finn’s group came up with – and ran – an overflow experiment with many different densities and even more colors. While the movie didn’t…
Cylinder collapse on a cone
Water running uphill during spin-down – how much more awesome can it get? After hours, when all but the most curious students had left, Rolf and I ran another collapsing…
Salt fingering
My absolute favorite experiment ever: salt fingering. I know I’ve said it before about another experiment, even today, but this is my absolute favorite experiment and I still get endlessly…
Hetonic explosion
Trying to tweak conditions to force a set number of vortices. We’ve done the hetonic explosion again. This time the group was super careful to calculate the Rossby radius correctly,…
Thermally driven circulation
One of my all-time favorite experiments. The salt group got a bit bored from watching ice cubes melt, so I suggested they look at temperature differences for a change, and…
Hadley cell circulation – slow rotation
In order to not be in the eddying regime, this time we are rotating our tank as slowly as possible. Since we ran the Hadley cell experiment the other day,…
Overflows
The unavoidable tank experiment when playing with Rolf ;-) After the first attempt – embarrassingly shown by the instructors – failed miserably, one of our groups ran the overflow experiment successfully.…
Hadley cell experiment
Cooling and rotation combined. (deutscher Text unten) I can’t believe I haven’t blogged about this experiment before now! Pierre and I have conducted it a number of times, but somehow…
Hetonic explosion
Or, an experiment on this blog often known as “slumping column”. (deutscher Text unten) If you don’t scale your tilting of frontal surfaces under rotation experiment correctly, you get a phenomenon…
Forced internal waves in a continuous stratification
Plus all kinds of dyes. (deutscher Text unten) Using the continuous salinity stratification created yesterday, Rolf and Daniel conducted a really cool experiment: They forced internal waves and watched them…
Creating a continuous stratification.
And watching internal waves – a data-model comparison. (deutscher Text unten) In an experiment similar to the one done by the group looking at the effects of temperature and salinity…
Effects of temperature and salinity on density and stratification
Removing a barrier between waters of different densities and watching what happens. (deutscher Text unten) Today, one of the groups performed a classical experiment (shown for example here) – but…
Why we absolutely need toy boats at the JuniorAkademie
Luckily I’m not the only one believing that we absolutely need remotely controlled boats! – Zum Glück bin ich nicht die Einzige, die findet, dass wir ferngesteuerte Boote brauchen! Mein…
Tilting of a frontal surface under rotation
Eddy in a rotating tank. This is an experiment that Pierre and I ran two years ago in Bergen but that – as I just realized – has not been…
Marsigli’s experiment
Density-driven flow. The experiment presented in this post was first proposed by Marsigli in 1681. It illustrates how, despite the absence of a difference in the surface height of two fluids,…
Guest post: The mystery of the cold room
Guest post by Kristin Richter! Today I’m excited to bring to you a guest post from Innsbruck, Austria, written by my friend Kristin Richter. Kristin ran the oceanography lab in Bergen…
Modeling the Denmark Strait Overflow
Ha, this is a bad pun. We are modeling the Denmark Strait Overflow – but in a non-numerical, small-scale-and-playdough kind of way. More than a year ago, Kjetil and I ran…
Cartesian divers – theoretical considerations
A bit more reflection on cartesian divers. When I wrote the two previous posts, I had known cartesian divers for a very long time in many contexts, for example as…
Cartesian diver – organic version
Using orange peel as cartesian divers. Guess what my mom told me when we were playing with cartesian divers the other day? That orange peel works really well as a…
Cartesian diver
Compressibility of water and air. Today I want to talk about the different compressibilities of water and air. Actually, no, I just want to show you an experiment. One way…
Oceanographic concepts and language (part 1)
About teaching in a language that is a foreign language for both your students and yourself. Most of my teaching so far has happened in English to mainly non-native English…
Mediterranean outflow
Students demonstrating the mediterranean outflow in a tank. As reported earlier, students had to conduct experiments and present their results as part of CMM31. Niklas chose to demonstrate the mediterranean outflow…
Ship-generated internal waves
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…
How sound is refracted towards the regions of minimum speed.
Students acting out the process of sound being refracted towards the region of minimum speed. We’ve been talking about refraction lately. Waves get bent in the direction of lower velocity.…
Fjord circulation
Tank experiment on a typical circulation in a fjord. Traditionally, a fjord circulation experiment has been done in GEOF130’s student practicals. Pierre and I recently met up to test-run the…
Dangers of blogging, or ice cubes melting in fresh water and salt water
When students have read blog posts of mine before doing experiments in class, it takes away a lot of the exploration. Since I was planning to blog about the CMM31…
Measuring density
Students build a device to measure density. As described in this post, I like to have students build “instruments” to measure the most oceanographic properties (temperature, salinity and density). I…
How a CTD works
Movie on how the most important instrument in oceanography works. On our cruise on the WHOI research vessel Knorr in 2011, Sindre Skrede (find him on twitter or vimeo for many more…
Filling the tank
A movie of patterns observed in the flow when filling the tank for this experiment. Even though there are tons of scientific things to discuss with this movie, like the…
Details of lee waves in the tank.
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…
Surface imprints of internal waves
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…
Internal (lee) waves in a tank.
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…
Internal waves in a bottle
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…
Melting ice cubes – one experiment, many ways (post 3/4)
Different didactical settings in which the “ice cubes melting in fresh and salt water” experiment can be used. In part 1 and 2 of this series, I showed two different…
Ice cubes melting in fresh water and salt water (post 2/4)
The “ice cubes melting in fresh water and salt water” experiment the way I usually use it in class. — Edit — For an updated description of this experiment please…
Ice cubes melting in salt water and freshwater (post 1/4)
Experiment to visualize the effects of density differences on ocean circulation. This is the first post in a series on one of my favorite in-class experiments; I have so much…
And even more on density
My favorite experiment. Quick and easy and very impressive way to illustrate the influence of temperature on water densities. Today in the “introduction to oceanography” (GEOF130) we conducted my favorite…
More on density
Extremely simple experiment to illustrate the effect of density differences. At room temperature, will coke cans float or sink in freshwater? And how about coke light? Btw, this experiment is…
How to measure temperature, salinity and density
Three in-class experiments run in parallel. Great if you want to discuss how properties are measured and what kind of difficulties you might encounter. Temperature, salinity and density are the…