Category Archives: hands-on activity (easy)

Thinking about the Doppler effect as of a boat sailing against the waves!

I can’t believe I haven’t written about this on my blog before, thanks Markus Pössel for reminding me of this great way to understand the Doppler effect!

Doppler effect, or why ambulances change their sound as they race past you

Doppler shift is everywhere, but it’s maybe not obvious how to imagine what’s going on if you think of sound waves.

But look at the picture below. Can you imagine the sound of those waves lapping against the shore?

Now imagine taking a speed boat riding out on the water. Can you feel how you are bouncing over the wave crests, and notice how you are meeting them a lot more often than when you were standing on the beach, looking out on the water?

Or imagine being a surfer, riding that perfect wave. You are staying with the same wave crest for a really long time, while in front of you creat after crest breaks on the beach.

Yes, the Doppler effect is as easy as this! As you are moving with or against the waves, their frequency changes. Totally obvious when you think about waves on water, right? But the same happens with sound waves, and in their case, a changed frequency means that the sound appears to change pitch. If the ambulance is coming towards you, the sound gets higher and higher, and then as it races away, it gets lower again. So now you don’t even have to look when you hear an ambulance, you know whether it’s coming or going! (Just kidding! Please definitely look out, anyway, and don’t get run over!)

A #scicommbookforkids for #scicommchall

I hope by now you have heard about my pet project of the moment: #scicommchall! For #scicommchall, I give myself (and quite a few other people by now) monthly challenges related to trying out new science communication formats. And this month, we are doing science communication books for kids! (For more instructions, see #scicommchall’s post. And everybody is welcome to join!).

My book deals with learning to observe where the wind is coming from (English version at the end of this post, too).

I think it turned out quite nicely!

I did struggle a little with the very short format — only six pages inside the book, plus a cover — but quite liked the challenge of having to come to the point.

The flag on the cover, in case you were wondering, is that of my hometown Hamburg.

I hope this book is actually useful and fun for kids (I did include some kids’ humor, or at least I tried ;-))

And I know what I would include if I wasn’t too lazy to re-draw the images: A question about on which side of some kind of structure one would sit down if one wanted shelter from the wind. Bummer I forgot to include that!

Anyway, here is the download (German & English). Please let me know what you think, I’d love to get some feedback!

Click to download

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 posts…

“Kitchen oceanography” brings the ocean to your house or class room!

Oceanography is often taught in a highly theoretical way without much reference to students’ real life experience. Of course a sound theoretical basis is needed to understand the complexity of the climate system, but sometimes a little “kitchen oceanography” — doing experiments on oceanographic topics with household items — goes a long way to raise interest in the kind of processes that are not easily observed in the real world. I’ve previously written a lot about simple experiments you can perform just using plastic cups, water, ice cubes, and a little salt. But sometimes it’s even easier: Sometimes your oceanography is being served to you in a cafe!

Oceanic processes can be observed in your coffee!

Have you ever looked at your latte and been fascinated by what is going on in there? Many times you don’t just see a homogenous color, but sometimes you see convection cells and sometimes even layers, like in the picture below.

Layers in a latte.

Layers in a latte.

But do you have any ideas why sometimes your latte looks like this and other times it doesn’t?

When you prepare latte in the right way, many layers form

Layers forming in latte (and in the ocean or in engineering applications) are an active research field! In the article “laboratory layered latte” by Xue et al. (2017), the authors describe that the “injection velocity” of espresso into the warm milk has to be above a critical value in order for these pretty structures to form in a latte. They even provide a movie where you can watch the layers develop over a period of several minutes.

The homogeneous layers with sharp boundaries are caused by double-diffusive mixing

Double-diffusive mixing, which is causing the formation of these layers, is the coolest process in oceanography. In a nutshell, double diffusive mixing is caused by two properties influencing density having different rates of molecular diffusion. These different rates can change density in unexpected ways and an initially stable stratification (high density at the bottom, low density on top) can, over time, become statically unstable. And static instability leads to adjustment processes, where water parcels move in order to reach the position in the fluid where they are statically stable — the fluid mixes.

Layers in half a glass of latte.

Layers in half a glass of latte.

But there are more fascinating things going on with the latte. Would you expect this stratification to remain as clearly visible as it is in the picture above even though the glass is now half empty? I did not! And then check out what happens when you move the glass: Internal waves can travel on the boundaries between layers!

You can use this in class to teach about mixing!

Mixing in the ocean is mostly observed by properties changing over time or in space, and even though (dye) tracer release experiments exist, they are typically happening on scales that provide information on the large-scale effects of mixing and not so much on the mixing itself. And they are difficult to bring inside the classroom! But this is where kitchen oceanography and experiments on double-diffusive mixing come in. If you need inspiration on how to do that, I’ve recently published an article on this (unfortunately only in German), but there are plenty of resources on this blog, too. Or shoot me an email and we’ll talk!

P.S.: Even though the coffee company is displayed prominently in the pictures above, they did not pay for my coffee (or anything else). But if they’d be interested and make me a good offer, I’d definitely write up some fun stuff on learning oceanography with coffee for them ;-)

Experiment: Double-diffusive mixing (salt fingering)

On the coolest process in oceanography.

My favorite oceanographic process, as all of my students and many of my acquaintances know, is double-diffusive mixing. Look at how awesome it is:

Double-diffusive mixing happens because heat and salt’s molecular diffusion are very different: Heat diffuses about a factor 100 faster than salt. This can lead to curious phenomena: Bodies of water with a stable stratification in density will start to mix much more efficiently than one would have thought.

In the specific case of a stable density stratification with warm, salty water over cold, fresh water, finger-like structures form. Those structures are called “salt fingers”, the process is “salt fingering”.

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Salt fingering occuring with the red food dye acting as “salt”.

Even though salt fingers are tiny compared to the dimensions of the ocean, they still have a measurable effect on the oceanic stratification in the form of large-scale layers and stair cases, and not only the stratification in temperature and salinity, but also on nutrient availability in the subtropical gyres, for example, or on CO2 drawdown.

Over the next couple of posts, I will focus on double diffusive mixing, but less on the science and more on how it can be used in teaching. (If you want to know more about the science, there are tons of interesting papers around, for example my very first paper)

How to easily set up the stratification for the salt fingering process.

Setting up stratifications in tanks is a pain. Of course there are sophisticated methods, but when you want to just quickly set something up in class (or in your own kitchen) you don’t necessarily want to go through the whole hassle of a proper lab setup.

For double diffusive mixing, there are several methods out there that people routinely use.

For example the hose-and-funnel technique, where the less dense fluid is filled in the tank first and then the denser fluid is slid underneath with the help of a hose and a funnel. And a diffuser at the end of the hose. And careful pouring. And usually a lot more mixing than desired.

Or the plastic-wrap-to-prevent-mixing technique, where the dense fluid is put into the tank, covered by plastic wrap, and then the lighter fluid is poured on top. Then the plastic wrap is removed and by doing so the stratification is being destroyed. (No video because I was frustrated and deleted it right away)

Or some other techniques that I tried and didn’t find too impressive. (No videos either for the same reason as above)

But then accidentally I came across this method (as in: I wanted to show something completely different, but then I saw the salt fingers and was hooked):

Granted, this is not a realistic model of an oceanic stratification. But as you can see towards the end of that movie, that turns out to be a blessing in disguise if you want to talk about the process in detail. As you see in the movie, the salt fingers inside the bottle are much smaller than the salt fingers outside the bottle. Because, clearly, inside the bottle the warm water is cooled both at the interface with the cold water inside the bottle, and by heat conduction through the walls of the bottle, since the water is surrounded by cold water. The warm water that flowed out of the bottle and up towards the water’s surface is only cooled at the interface with the water below (the air above is warmer than the cold water). So this gives you the perfect opportunity to discuss the scaling of salt fingers depending on the stratification without having to go through the pains of actually preparing stratifications with different gradients in temperature or salinity.

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Self-portrait with salt fingers :-)

In my experience, the best salt fingers happen when you use hot water with dye (as the warm and salty top layer) and cold fresh water below. Salt fingers develop quickly, you don’t have the hassle of hitting the exact temperatures or salinities to make the density stratification statically stable, yet unstable in salinity, and it ALWAYS works.

 

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Double-diffusive mixing. Scale at the bottom is centimeters.

 

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Salt fingering in a tank. Scale at the bottom is centimeters.

And look at how beautiful it looks! Do you understand why I LOVE double diffusion?

P.S.: This text originally appeared on my website as a page. Due to upcoming restructuring of this website, I am reposting it as a blog post. This is the original version last modified on November 4th, 2015.

I might write things differently if I was writing them now, but I still like to keep my blog as archive of my thoughts.

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 it to make bread, and he sent me a couple of pictures the resulting bread! Of course, I asked if I could share it as a guest post on my blog, so here we go (Thanks, Martin Haswell, for this unique and inspiring contribution! See, everybody? Real-world impact of science blogging!):

Making bread using seawater

There is nothing like a challenge from your best friend, to do something that you’ve never done before but might just work. In my case, make bread using sea water.

My friend Mandy had brought me back from New York a copy of Jim Lahey’s book “My Bread”. Jim’s ‘no-knead’ method of bread making uses flour, water, salt (normally) and a tiny amount of yeast – and a lot of time, but no kneading. The dough is left for a long time to rise and is baked very very hot, and makes a tasty and crusty loaf.

Jim has a recipe in his book called  “Jones Beach Bread” in which he uses seawater instead of house water plus salt to make the dough. Knowing that we both used the ‘no-knead’ recipe and that I had access to a beach with clean water, Mandy challenged me to follow this recipe, and this is how it went.

Martin collecting seawater on the beach, far enough out to miss most of the turbidity

Martin collecting seawater on the beach, far enough out to miss most of the turbidity

Martin checking the seawater sample for sand or other impurities

Martin checking the seawater sample for sand or other impurities

Jim Lahey’s book “My Bread” that contains Jim’s 'no-knead' method of bread making used for the bread in this blog post

Jim Lahey’s book “My Bread” that contains Jim’s ‘no-knead’ method of bread making used for the bread in this blog post

Waiting for the bread to raise

Waiting for the bread to raise

The finished result! Doesn't it look delicious?

The finished result! Doesn’t it look delicious?

The bread tasted very good, crusty and tasty. I made two loaves, one with the seawater filtered through a coffee filter and the other with unfiltered seawater. Normally this recipe needs around 12-18 hours rising time but this took 28 hours for the two risings, but it is winter in southern Brasil (Florianópolis, on the coast) and the day temperature was only 72F (22°C) on the day of the experiment. It’s also possible that the greater proportion of salt might have hindered the development of the yeast and held back the rise. This wasn’t a very scientific experiment.

I calculated that Lahey’s original no-knead’ recipe calls for 8g salt to 300g of water which makes 26.66g per litre, whereas sea water (according to Mirjam’s 2013 blog is 35g/litre so this should mean that the sea bread loaf should be around 30% more salty than normal; if I’m honest, it didn’t tasty significantly more salty).

Further experiments: the obvious test would be a sea water loaf vs conventional made, risen and baked at the same time.

Notes:

The Jones Beach in Jim’s recipe is the Jones Beach State Park on Long Island, New York State. The current water cleanliness data is here (PDF), scroll down for the Jones Beach SP results.

The beach that I collected my sea water from is currently ‘própria‘ but I wouldn’t collect after heavy rain (runoff) or heavy seas (turbidity).  As a safety precaution one could boil the sea water and let it cool just enough before using. In fact, when the weather is cold, that would be the best way of giving the bread a good start.

[note by Mirjam: I’ve done a super quick google search and it looks like typical salinities for the Florianopolis area can go down to 30-ish and thus be lower than the typical, open ocean value of 35, but during summer they might go up to 37 (Pereira et al., 2017) but in addition to the seasonal changes, your salinity probably depends very much on which beach you took the water sample at (for example if it was a lagoon-ish beach with a lot of freshwater runoff and not so much mixing with the open ocean). Since you collected the water fairly close to the beach and during winter, it’s likely that the salinity wasn’t quite as high as the 35 I mentioned (which would explain why the bread didn’t taste as salty as you might have expected). If you wanted to know the exact salinity next time you are making bread, an easy method to measure the salinity of sea water would be to boil a liter until all the water has evaporated and weigh the remaining salts. This isn’t very precise for oceanographer-standards, since some of the substances that oceanographers include in their measure of “salinity” in sea water at normal temperatures might actually evaporate with the water, but since the largest constituent of the “salt” in sea water is just normal NaCl, the mistake you’d be making is probably small enough for cooking purposes, and you’d get a general idea of how “typical” your sample is in terms of seawater salinity.]

Bio:

Martin Haswell is an English photographer who loves travel and making bread.

Experiment: Temperature-driven circulation

My favorite experiment. Quick and easy and very impressive way to illustrate the influence of temperature on water densities.

This experiment is great if you want to talk about temperature influencing density. Although it doesn’t actually show anything different from a temperature driven overturning experiment, where circulation is determined by hot water rising and cold water sinking, somehow this experiment is a lot more impressive. Maybe because people are just not used to see bottles pouring out with the water coming out rising rather than plunging down, or maybe because the contrast of the two bottles where one behaves exactly as expected and the other one does not?

Anyway, it is really easy to do. All you need is a big jar and two small bottles. Cold water in one of the small bottles is dyed blue, hot water in the other small bottle is dyed red. Both are inserted in the jar filled with lukewarm water (movie below).

Using bottles with a narrower neck than mouth is helpful if you want to use the opportunity to talk about not only temperature-driven circulation, but also about double-diffusive mixing (which you see in form of salt fingers inside the red bottle in the picture above).

Isn’t this beautiful?

P.S.: This text originally appeared on my website as a page. Due to upcoming restructuring of this website, I am reposting it as a blog post. This is the original version last modified on December 2nd, 2015.

I might write things differently if I was writing them now, but I still like to keep my blog as archive of my thoughts.

Tides themselves don’t induce (a lot of) mixing, only tides hitting topography do. An experiment.

As you might have noticed, the last couple of days I have been super excited to play with the large tanks at GFI in Bergen. But then there are also simple kitchen oceanography experiments that need doing that you can bring into your class with you, like for example one showing that tides and internal waves by themselves don’t do a lot of mixing, and that only when they hit topography the interesting stuff starts happening.

So what we need is a simple 2-layer system and two different cases: One with topography, one without. And because we want to use it to hand around in class, the stratification should be indestructible (-> oil and water) and the container should be fairly tightly sealed to prevent a mess.

Here we go:

There definitely is a lot to be said for kitchen oceanography, too! Would you have thought that using just two plastic bottles and some oil and water could give such a nice demonstration?

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 first concepts people hear about in the context of ocean and climate is the “great conveyor belt”. The great conveyor belt is a very simplified concept of the global ocean circulation, which is depicted as a single current that spans the world oceans (see Figure 1 below). In this simplified view of the global circulation, water flows as a warm, global surface current towards the North Atlantic, where it cools, sinks and finally returns southward and through all the world oceans near the bottom of the ocean. Water is transported back to the surface through mixing processes and starts over its journey again as a warm surface current. While in reality some part of the conveyor belt is wind-driven and many processes come to play together, a large part of the circulation can be explained by the water sinking due to cooling at high latitudes.

Conveyor_belt

Figure 1: The great conveyor belt. My sketch on top of a map from http://www.free-world-maps.com

This can be very easily represented in a demonstration or experiment.

Materials

What we need for this experiment:

  • 2 gel pads for sports injuries, one hot, one cold
  • red and blue food coloring
  • a clear plastic container to act as tank
  • a pipette or drinking straws to disperse drops of dye
  • dye crystals to show the circulation. Can also be drops of a different color dye.
Running the experiment

The container is filled with lukewarm water.  On the “poleward” end, we add the cold pad, the warm one at the “equatorward” end of the tank.

Blue dye is tripped on the cold pad to mark the cold water, red dye on the warm pad as a tracer for warm water.

overturning

Thermally-driven overturning circulation: Warm water flowing near the surface from the warm pad on the left towards the right, cold flow from the cool pad at the bottom right to left.

A circulation develops. If you drop dye crystals in the tank, the ribbon that formed gets deformed by the currents for yet another visualization of the flow field.

overturning2

Thermally-driven overturning circulation. In the middle of the tank you see a ribbon of dye, caused by falling dye crystals, being transformed by the currents in the tank.

Here is the video:

What observations to make

Besides the obvious observation, watching, there are a couple of things you can ask your audience to do.

For example, if they carefully slide their fingers up and down the side of the tank, they will feel the warm water near the surface and the cold water at the bottom.

If you have a clear straw, you can use it as plunging syphon to extract a “column” of water from the middle of the tank, showing again the stratification of red, clear, blue.

If you put little paper bits on the surface, you will see them moving with the surface current.

Can you come up with more?

Who can I do this experiment with?

Someone recently asked me whether I had ideas for experiments for her course in ocean sciences for non-majors. Since most of the experiments I’ve been showing on this blog were run in the context of Bachelor or Master oceanography-major courses, she didn’t think that the experiments were as easily transferable to other settings as I had claimed.

So here is proof: You can do pretty complex experiments with non-university level students. To prove my point, let’s go to a primary school.

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Me running the overturning experiment with a primary school class in 2012.

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The overturning experiment as seen by the teacher (2012).

Of course, you can adapt this experiment to different levels of prior knowledge. For example, in the primary school, I introduced this experiment by showing pictures of lions and penguins and other animals that the pupils knew live in warm or cold climates, and we talked about where those animals live. In the end this aimed at how temperatures are a lot colder at the poles than at the equator. This is the differential heating we need for this experiment to work. While this is something that I felt the need to talk about with the primary school kids, this can be assumed as a given with older students (or at least that is the assumption that I made).

With the university-level courses, one of the points that I made sure came up during the discussion are the limitations of this model. For example that we apply both heating and cooling over the full depth of the water column. How realistic is that? Or the fact that we heat at one end and cool at the other, rather than cooling on either end and heating in the middle?

Let me zoom in on something in the picture above.

IMG_3214_2

Curious features in the thermal conveyor experiment. Do you know what this is about?

Do you see these weird red filaments? Do you think they are a realistic part of the thermal circulation if it was scaled up to a global scale?

Of course not. What we see here is salt fingering. This is a process that is caused by the different diffusivities of heat and of the red dye. And while it is pretty large scale in our small tank, you cannot scale it up just like that when talking about the real ocean. And it is also really difficult to get rid of salt fingers for this experiment, in fact I haven’t yet managed. But I am open to suggestions! :-)

Another point that I would talk about with university-level students that I would probably not bring up with primary school kids (- although, why not if I had more time than just those 45 minutes per class?) is that ocean circulation is driven by more than just differential heating. Even when just considering the density-driven circulation, that is additionally influenced by changes in salinity. Put that together with wind-driven circulation and we are starting to talk about a whole new level of complicated…

But anyway. My point is that even primary school kids can benefit from doing this kind of experiments, even if what they take away from the experiments is not exactly the same as what older students would take away.

Discussion
As with every experiment, it is a lot easier for an “expert” to observe what he or she wants to observe, than for their students.
The left column in the figure above is taken from an instruction for educators and parents of primary school kids I wrote a while back. When taking the pictures I was aware that the quality in terms of signal-to-noise was not very good (and in fact people [i.e. my parents] even told me). In my defense: The pictures of this experiment I shared on this blog are all less noisy, and I even explicitly addressed and discussed some of the noise! But still, only when reading that article today I fully appreciated how difficult it might be to see the signal through the noise (especially when the speech bubbles in the picture don’t even point exactly to the right places!), and how distracting it probably is when I implicitly assume that students see the signal and even start discussing the noise more than the signal.

So what we see above are, in the left column, the pictures I originally shared in that manual. In the middle column, I’m showing what I see when I look at the pictures on the left. And then in the right column I’m drawing what people might be seeing when looking at that same experiment. No idea if that really is what students see, but looking at the pictures now, there is actually no reason why they should see what I see. See?
One indicator of the signal-to-noise ratio and of what students actually perceive as important can be found in the three little essays the primary school kids show in the picture above wrote after my visit in December 2012: Two out of the three explicitly mention that I used a yoghurt beaker as heating on the one end of the tank (while the third only refers to a beaker). Clearly that seems to have been a very important observation to them.
So what do we take away from this? I, for one, am going to make sure to pay more attention to the signal-to-noise ratio when showing demonstrations. And if there happens to be a lot of noise, I am going to make it a lot clearer which part of the signal is actual signal, and which is noise. Lesson learned.

P.S.: This text originally appeared on my website as a page. Due to upcoming restructuring of this website, I am reposting it as a blog post. This is the original version last modified on January 13th, 2016.

I might write things differently if I was writing them now, but I still like to keep my blog as archive of my thoughts.

Experiment: Oceanic overturning circulation (the easiest version)

“The easiest” in the title of this page is to show the contrast to a “slightly more complicated” version here.

Background

One of the first concepts people hear about in the context of ocean and climate is the “great conveyor belt”. The great conveyor belt is a very simplified concept of the global ocean circulation, which is depicted as a single current that spans the world oceans (see Figure 1 below). In this simplified view of the global circulation, water flows as a warm, global surface current towards the North Atlantic, where it cools, sinks and finally returns southward and through all the world oceans near the bottom of the ocean. Water is transported back to the surface through mixing processes and starts over its journey again as a warm surface current. While in reality some part of the conveyor belt is wind-driven and many processes come to play together, a large part of the circulation can be explained by the water sinking due to cooling at high latitudes.

Conveyor_belt

Figure 1: The great conveyor belt. My sketch on top of a map from http://www.free-world-maps.com (used with permission)

The experiment

Since the global conveyor belt is such a basic concept that we come across in many different contexts, it is very useful to have a good demonstration of what is happening in the world ocean. Plus demonstrations and experiments are always fun!

I here present a very simple experiment that can be used for many different purposes. In science outreach, for example on a fair or in a talk, to catch people’s attention and raise an interest in oceanography. In schools to do the same, or to connect the fascination of the ocean to school physics and talk about density, convection, heat. At university to do all of the above, as well as to practice writing lab reports, talk about the scientific method or the validity of simplifications in theoretical or physical models.

Materials needed

All we need to run this experiment is

  • a clear plastic container
  • lukewarm water
  • red and blue food dye
  • an ice cube tray and
  • access to a freezer.

Ideally we’d also have a thermos or some other kind of insulation to keep the ice cubes frozen until we start running the experiment. To prepare the experiment, all we need to do a half a day ahead is mix some blue food dye into the water that we put in the ice cube tray, and freeze the ice cubes.

Running the experiment

To run the experiment, we start out by filling our “tank” with lukewarm water. Let it settle for a bit. Now we decide for one end of your tank to be the “equator” end. There, we add some red food dye (see Figure 1).

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Figure 2: Tank with luke warm water. Red food dye added to the “warm” end of the tank.

Then we add the blue ice cubes to the “poleward” end of our tank (see Figure 3).

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Figure 3: Blue ice cubes melting at the poleward end of the tank. The cold melt water sinks to the bottom of the tank and then spreads “equatorward”.

The cold melt water from the ice cubes is denser than the lukewarm water in the tank and therefore sinks to the bottom of the tank where it spreads “equatorward”, pushing below the warmer water. This can be seen where the red water is pushed upwards and “poleward”.

Discussion

Of course, the processes at play here are not exactly the same as in the real ocean.

For one, deep water formation is NOT due to ice cubes melting in lukewarm water. In fact, melting of sea ice will in most cases not lead to any kind of sinking of water, since the melt water is fresh and the surrounding ocean water is salty and hence denser than the melt water. Cooling in the ocean happens through many processes at the surface of the ocean, like radiation into space and evaporation.

Heating is also represented in an extremely simplified way in this experiment. Heating in the ocean occurs mainly (with the negligible exception of thermal springs in the ocean) by radiative heating from the sun, and at the surface only. We “heat” throughout the whole depth of the ocean by filling the whole tank with lukewarm water.

Also, the mixing processes that, in the real ocean, bring deepwater back to the surface are not represented here at all. Our tank will eventually fill with a layer of cold water at the bottom (See Figure 4), and the circulation will stop once all the ice has melted.

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Figure 4: Blue ice cubes melting at the poleward end of the tank. The cold melt water sinks to the bottom of the tank and then spreads “equatorward”. Slowly, the tank fills with cold water.

Why use the experiment?

Even with all the simplifications described above, this experiment is a great first step in becoming intrigued by the ocean, and towards understanding ocean circulation. Seeing the melt water sink from the ice cubes is fascinating no matter how little interest one might have in the physics that cause it. Sliding a finger up and down the side of the tank lets you experience – feel! – how the temperature changes from warm near the surface to very cold near the bottom. Actually physically feeling this is a lot more impressive than just watching the experiment or even just being shown temperature sections of the ocean. And the experiment invites you to play: What if you added little pieces of paper on the water surface, would you see them move with the flow towards the cold end of the tank? Or if you dropped a dye crystal in the middle of the tank, would the dye ribbon that forms be deformed by the currents in the tank? And what if you added twice as many ice cubes, would the currents be twice as fast?

This is pretty much the easiest experiment you can imagine. If you are afraid of what food dye might do in the hands of your participants, you don’t even need to let them handle it themselves, even when they are working in small groups with individual tanks: just go around dripping the dye in and then add the dyed ice cubes yourself. While someone might still tip over a tank and spill the water, this has yet to happen to me. Especially since, before running the experiment, you will have pointed out that they need to make sure not to bang against the tables as to not disturb the experiment. And now apart from making sure that the ice cubes are frozen when you want to run this experiment, there is nothing that can go wrong. So why not try this experiment next time you want to talk about global ocean circulation?

Watch a video of the experiment here:

What would I do differently next time?

Next time, I would pay attention to which end of my tank will represent the equatorward and poleward side of the ocean. Not that it matters much, but in most graphics of sections through the North Atlantic, the northern end will be on the right side and the southern end on the left. If the experiment is set up the other way round (as on all pictures and movies above) you will need to remember to point it out (or even mark it on the tank with a sharpie or such).

Still scared of the hassle of running experiments?

And for all of you who hesitate doing awesome experiments because it looks like you need so much equipment: No you don’t. Here is a “making of” shot from how I did this experiment on my coffee table while sitting on my couch. The background is the back of an old calendar sheet, clipped to the back of a chair. And that’s it.

Screen shot 2015-11-02 at 3.41.24 PM

The setup for my experiment.

P.S.: This text originally appeared on my website as a page. Due to upcoming restructuring of this website, I am reposting it as a blog post. This is the original version last modified on November 4th, 2015.

I might write things differently if I was writing them now, but I still like to keep my blog as archive of my thoughts.

Four steps to great hands-on outreach experiences

Part 1 and 2 of this post were first posted on the EGU’s blog on Jan 29, 2016, and Feb 29, 2016, respectively.

Part 1 gives four steps to outreach activities, part 2 uses an example to further illustrate those four steps.

Part 1: For the best hands-on outreach experiences, just provide opportunities for playing!

 

“For the best hands-on outreach experiences, just provide opportunities for playing!” I claim. Seriously? You wonder. We want to spark the public’s curiosity about geosciences, engage the public in thinking about topics as important as sea level rise or ocean acidification, and provide learning experiences that will enable them to take responsibility for difficult decisions. And you say we should just provide opportunities for them to play?

Yes. Hear me out. Playing does not necessarily equal mindlessly killing time. Kids learn a lot by playing, and even grown ups do. But if you prefer, we can use the term “serious play” instead of just “play”. Using the term “serious play” makes it clear that we are talking about “improvising with the unanticipated in ways that create new value”, which is exactly what outreach should be doing: getting people intrigued and wanting to understand more about your topic.

So how would we go about if we wanted to create outreach activities which gave the public opportunity to play in order to lure them into being fascinated by our field of science? There are several steps I recommend we take.

  1. Identify the topic nearest and dearest to your heart

Even if your aim is to educate the public about climate change or some other big picture topic, pick the one element that fascinates you most. If you are really fascinated by what you are showing, chances are that the excitement of doing the activity will carry over to your audience. Plus, once you have this really great activity, you will likely be asked to repeat it many times, so you had better pick one that you love! J

Me, I am a physical oceanographer. I care about motion in the ocean: Why and how it happens. Consequently, all of my outreach activities have people playing with water. Sometimes at different temperatures, sometimes at different salinities, sometimes frozen, sometimes with wind, but always with water.

  1. Find an intriguing question to ask

Questions that intrigue me are, for example, “do ice cubes melt faster in fresh water or in salt water?”, “how differently will ice look when I freeze salt water instead of fresh water?” or “what happens if a stratification is stable in temperature and unstable in salt?”. Of course, all these questions are related to scientific questions that I find interesting, but even without knowledge of all the science around them, they are cool questions. And they all instantly spark follow-up questions like “what would happen if the ice cubes weren’t floating, but moored to the ground?”, “what if I used sugar instead of salt?”, “wait, does the food dye influence what happens here?”. And all of those questions can be investigated right then and there. As soon as someone asks a question, you hand them the materials and let them find the answer themselves. That is why we talk about hands-on outreach activities and not demonstrations: It is about actively involving everybody in the exploration and wonder of doing scientific experiments!

  1. Test with family, friends and colleagues

Many, if not all, the outreach activities I am using and promoting have been tested on family, friends and colleagues before. You know that you have found an intriguing question when your friends sacrifice the last bit of red wine they brought at a Norwegian mountain cabin, to use as stand in for food dye in an experiment you just told them about, because they absolutely have to see it for themselves!

By the way, this is always good to aim at with outreach activities: always try to keep them easy enough to be recreated at a mountain cabin, in your aunt’s kitchen, at the beach or anywhere anyone who saw it or heard about it wants to show their friends. People might occasionally have to get a little creative to replace some of the materials, but that’s part of the charm and of the inquiry we want!

  1. Bring all the materials you need, and have fun!

And then, finally, Just Do It! Bring all your materials and start playing and enjoying yourself!

But now they can play with water and dye. That doesn’t mean they understand my research!

True, by focussing on a tiny aspect you won’t get to explain the whole climate system. But you will probably change the mindset of your audience, at least a little bit. Remember, you studied for many years to come to the understanding you have now, it is not a realistic expectation to convey all that in just one single outreach occasion. But by showing how difficult it is to even understand one tiny aspect (and how much there is still to discover), they will be a lot more likely to inquire more in the future, they will ask better questions (to themselves or to others) and they will be more open to learning about your science. Your activity is only the very first step. It’s the hook that will get them to talk to you, to become interested in what you have to say, to ask questions. And you can totally have backup materials ready to talk in more depth about your topic!

But what if it all goes horribly wrong during my activity?

The good thing is that since you are approaching the whole hands-on outreach as “get them to play!” rather then “show them in detail how the climate system works”, there really isn’t a lot that can go wrong. Yes, you can mess up and the experiment can just not show what you wanted to show. But every time I have had that happen to me, I could “save” the situation by engaging the participants in discussing how things could work better, similar to what Céline describes. People will continue to think about what went wrong and how to fix it, and will likely be even more intrigued than if everything had worked out perfectly.

But what if I am just not creative enough to come up with new ideas?

First, I bet once you start playing, you will come up with new ideas! But then of course, we don’t need to always create outreach activities from scratch. There are many awesome resources around. EGU has its own large collection in the teacher’s corner. And of course, Google (or any websearch of your choice) will find a lot. And if you were interested in outreach activity in physical oceanography specifically, you could always check out my blog “Adventures in Oceanography and Teaching”. I’m sure you’ll find the one activity that you will want to try yourself on a rainy Sunday afternoon. You will want to show your friends when they comes over to visit, and you’ll tell your colleagues about it. And there you are – you found your outreach activity!

 

Part 2: One example of how playing works in outreach activities!

 

In part 1, I talked about hands-on outreach in very general terms, and identified four steps to great outreach. Today, I want to talk about those four steps in more detail, using one of my favourite outreach activities as an example.

Step 1. Identify the topic nearest and dearest to your heart

Me, I am a physical oceanographer. I care about motion in the ocean: Why and how it happens. Consequently, all of my outreach activities have to do with water. Sometimes at different temperatures, sometimes at different salinities, sometimes frozen, sometimes with wind, sometimes with ships, but always with water.

Today, let’s concentrate on thermohaline circulation as the topic we want to get people interested in. That sounds like a lot, so lets break it down: we want to know how oceanic circulation is influenced by both heat and salt in the ocean. To boil this down to one short activity, let’s take away the ocean (and with that all the complicating influences of Earth’s rotation, or topography of ocean basins) and only look at what heat and salt do with water in a tank. In fact, let us focus on different temperatures at first. The easiest way to do this is to introduce water of one temperature into a volume at a different temperature, this way we don’t have to deal with the heating or cooling processes.

Introducing water can mean pouring it into the larger tank, which will lead to some kind of stratification (provided your temperatures are different enough). In order to see the stratification, it always helps to have food dye in the water you are introducing (always put food dye in the smaller volume of water, makes it a lot easier to see the contrast!). To make things most interesting, it might be nice to show two cases simultaneously: pouring hot water and cold water into a lukewarm tank. And, since we see that the hot water forms a layer on top of the lukewarm water and the cold water at the bottom, wouldn’t it be much more fun to introduce them both somewhere at medium height and see what happens?

2_Slide1

Two bottles, one filled with hot water (dyed red) and one filled with cold water (dyed blue) in a larger container of lukewarm water.

Step 2. Find an intriguing question to ask

Depending on who you want to reach as your main audience, you might need to ask different questions. For some audiences, the focus needs to clearly be on your activity’s connection to climate. For other audiences, the questions can be a simple “Wow, that looks weird. Can you figure out what is going on here?”. Depending on the context I was doing my activity in, I could for example ask:

  • Why is the bottle with the red water “pouring up”? The audience I might ask this question are for example kids in a school setting that I am wanting to get excited in science in general. 2_Slide2
  • How can I fill the green cup with hot water without touching it? Audience here could be the general public at a science fair, and if someone manages to fill the green cup, they win a sticker. This questions definitely makes people want to give it a try!2_Slide3
  • What can these fingers tell us about how water mixes in the ocean? This question is for an audience that already knows a lot about the ocean and physical processes in it, for example university students, or a very interested general public.2_Slide4
  • In the subtropical gyres you have a strong salinity stratification. How can nutrients get to the surface ocean? This question is closely related to the one before, but here the element of play isn’t as prominent. So this would be for an audience that knows a lot about ocean physics and biogeochemistry already, like university students or even colleagues at scientific conferences.2_Slide5
  • What drives global ocean currents? This is again a question that you might ask the general public since on one hand not a lot of knowledge about ocean physics is required, and it is on the other hand very easy to see the connection between your activity and the ocean.

    2_Slide6

    Map modified after free-world-maps.com

Step 3. Test with family, friends and colleagues

This step is important for several reasons.

First, you want to work out (most of) the kinks in the activity before using it in front of a large audience. This includes

  • knowing what kind of materials you actually need to run it (For example, I tend to forget that I not only need large containers of water that are prepared at the right temperatures and salinities for several repeats of the experiment, but that in order to set up the experiment for repeats, I need somewhere to get rid of the water from previous experiments),
  • seeing people get really excited about the activity (which is a good memory to calm you down when you get nervous about doing the activity in public for the first time), or, if the aren’t, a good time to tweak the activity a little.
Step 4. Bring all the materials you need, and have fun!

And there you are – ready to do your outreach activity! For your big day, this is what I would recommend:

  • It sounds lame, but you should have a good packing list that includes not only stuff that you need to run the activity, but also stuff that you need to store stuff in on your way home, when everything is wet and full of food dye.
  • If you are about to play with a lot of food dye or other staining substances, consider not wearing your favourite pair of white jeans. Consider also whether your scarf will be constantly hanging in your water tank getting wet, and whether your hair might get caught somewhere.
  • Bring a friend to do the activity with you. It’s more fun, and it really takes away a lot of stressors if there are two people there (Run out of water? No worries, one of you can run and fetch more water while the other talks to people who still want to know what is going on. Question you have no idea how to answer? She will know, or you can look it up together later. Need the loo? How great is it that you don’t have to pack all your stuff and take it with you? ;-))
  • Have someone you know for sure is interested in your activity show up early on to look at it and talk to you about it. Nothing makes it easier for other people to approach and join you in your conversation and activity as someone who is already there and obviously excited. (You can also use your friend mentioned above to play this role until things get going)
  • Bring “backup materials”. Even if your activity is only very vaguely related to your research, bring a current poster of your research (maybe not the A0 version, but A3 or A4) and anything you typically show when talk about your research (Maps? Figures? Instrumentation?). When you get talking to people, chances are you will get talking about how your activity is related to bigger research questions, and you will want to be able to talk about them.
  • And bring a different kind of “backup materials”: Bring pictures and/or movies of your experiment to show what it should have looked like in case the freezer that was supposed to have turned your ice cube tray full of water into ice cubes over night turns out to be a cold room.
  • Take pictures. This one is super important, and I always forget about it in the heat of the moment. You constantly need that picture with you and a bunch of kids looking at your activity for grant proposals or for end-of-year reports!
  • Last but not least: Have fun and take this as a great opportunity to play! Discover features in your activity that you have never noticed before, and, together with your audience, “improvise with the unanticipated in ways that create new value” – I guarantee that it will happen!

Do you have stories of your outreach to share? Any experiments we should all know about? I’d love to hear from you, please leave a comment below!

P.S.: This text originally appeared on my website as a page. Due to upcoming restructuring of this website, I am reposting it as a blog post. This is the original version last modified on February 1st, 2016.

I might write things differently if I was writing them now, but I still like to keep my blog as archive of my thoughts.