Turns out building a rotating table isn’t as easy as we had hoped, because my Lazy Susan’s axle is unfortunately really off centre (how did I never notice before?), which makes it pretty difficult to drive it with a grinding wheel, and the LEGO motor we were using only has one speed (which would have to be regulated by changing the diameter of the gears). That makes it really difficult to spin up a tank at rest if you go at it zero to full force…
But we got it to spin! Look at the cool paraboloid surface!
Next issue, though: my awesome glass vase which looks like it should work well as a tank has a really irregular bottom, which makes it very difficult to have anything stand in the centre without too much of a wobble. Also, for the Hadley Circulation experiment we were trying to set up here, when do you add in the cooling in the center? Would be best to do it after the tank is spun up, but that is such a pain to do! And I messed up the dye here, too.
But at least you can see a little bit of what it will be like when we are done, right?
better Lazy Susan
think about how to film it, therefore either have a co-rotating camera or a white background
And then it will be almost ready to be used in teaching. Well, almost…
Funny how tank experiments that you think should be quick and easy to set up & run always take sooo much longer than expected. But it’s so much fun that I really don’t mind! :-)
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, I’ve been obsessed with running it again, this time with the slowest rotation possible in order to visualize a different flow regime – one were the heat transport happens through an overturning circulation rather than through eddies.
Unfortunately the camera we had mounted above the tank only started up halfway through the experiment (no idea how that happened!), so today you’ll only get snippets of this experiment. But all the more reason for us to run it again soon!
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 the documentation never happened. So here we go today! Martin and I ran the experiment for our own entertainment (oh the peace and quiet in the lab!) while the kids were watching a movie. But now that we’ve worked out some of the things to avoid (for example too much dye!), we’ll show it to them soon.
This is a classical experiment on general atmospheric circulation, well documented for example in the Weather in a Tank lab guide. The movie below shows the whole experiments, though some parts are shown as time lapse.
Für unsere eigene Unterhaltung haben Martin und ich dieses Experiment gemacht, während die Kinder mit allen Gruppen gemeinsam einen Film gesehen haben. Himmlische Ruhe im Labor! Aber wir werden es bald auch der Gruppe vorführen.
Dieses klassische Experiment zeigt, wie die großskalige atmosphärische Zirkulation in der Hadley-Zelle angetrieben wird und ich weiß auch schon, wie wir es beim nächsten Mal noch eindrucksvoller hinbekommen als bei diesem Mal!