What icebergs don't look like...

Whenever I'm inclined to beat myself up for spending far too long on twitter when I should be doing something useful, I remind myself that sometimes I'm doing something useful by being on twitter. If only because I occasionally come across such simple gems as this tweet by @GlacialMeg

@GlacialMeg is Megan Thompson Munson who is a PhD Student in Colorado where she studies Atmospheric and Oceanic Sciences and seems to have a particular interest in icebergs. And that is presumably what lead to this good-humoured rant a few months ago wherein she called upon scientists to start drawing ice-bergs right. And when you draw an iceberg right, it doesn't look anything like that in the picture to the side here...

This is one of those things that I feel I should always have known - and it connects with Leaving Cert Physics in several ways: equilibrium, heat and temperature, Archimedes, flotation and density all springing to mind. Basically, she points out that the classic ice-cream-cone shape of an iceberg drawing is clearly unstable (just as ice-cream-cones are unstable). Almost inevitably, there would be a weight imbalance in a structure arranged like that, which will create a moment around the centre of gravity and cause the whole thing to flip over - so that it lies longways in the water. And what's great fun is that in the replies to the twitter rant, Josh Tauberer chipped in with this tool - which allows you to sketch out any shape of iceberg you like with your finger, and then watch it shift in the water until it achieves stable equilibrium.

Its not only educational, but also curiously therapeutic. I've spent ages sketching out iceberg after iceberg and watching them shift in the water. And if you leave it on screen long enough, it will also mimic the heating effect of the sun - which obviously causes the above-water ice to melt, changing the shape and often causing the whole thing to flip over again. Which is something that apparently happens in nature and is one of the many reasons why its not a good idea to get too close to icebergs!

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