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A friend of mine is an academic, specialising in cold things (glaciers, tundra, kind of thing - can't be too specific as he's quite important) and occasionally gets bizarre letters from members of the public asking questions about various topics that he is supposed - at least in the popular mind - to know about. Recently, he received a letter from a gentleman in India, enclosing a photograph (above), and asking what could possibly have caused these amazing ice formations.
My friend thinks he has a clue, but I wondered what you thought.
Any ideas?
Wind currents round the building.
ReplyDeleteI would suggest a vent or strong draught at the top of the door that is pushing water droplets outward.
ReplyDeleteMy first thoughts as well. But does that explain the quite regular curves to the icicles? Ice formed in strong air currents tends to grow in straight lines (remember that lighthouse in the US a few weeks ago?).
ReplyDeleteAir currents circulating round obstructions won't be travelling in straight lines. Think of the trailing edge vortices that form on aeroplane wings. Exactly the same thing happens with liquids - think of rocks in a fast moving stream - but the difference is you can see what's going on.
ReplyDeleteIt's why car manufacturers have spent so much time wind tunnel testing to smooth the airflow over their vehicles. Any disturbed airflow is a source of drag.
Have you ever wondered why many trucks have a bit of rag tied to the wing mirror support? It's because the turbulence around the mirror makes the rag flap about and this keeps the glass clean!
Fair point - but I seriously doubt that turbulent airflow would create such consistent curves. What is striking about the image is that the icicles seem to echo each other. There is another possibility, which a careful look at the image will reveal, and which *may* fit the evidence better.
ReplyDeleteI have to say that there is no 'right answer' as such, only competing theories, and I am not qualified to judge, as I only got an E- in my Applied Hydrodynamics O-level.
http://en.wikipedia.org/wiki/Ice_spike Nice photograph.
ReplyDeletei think there would be too many impurities in the water for that to happen here. But it's an interesting phenomenon, which I hadn't heard of before, so thanks for the link.
ReplyDeleteI had similar ice in my guttering. It seemed to be caused by the fact that the guttering was full of ice and as sleet/ rain / snow continued to fall the water had nowhere to go so started to pour over the guttering. This almost immediately froze and formed patterns depending on the way the water flowed off the guttering. Any chinks in the guttering between sections or stones and leaves would force the water to follow certain routes over the edge before quickly freezing. Wish I'd photographed it :)
ReplyDeleteThe frozen mass from which the icicles are growing, appears to be rotating around what looks like a plastic coated pipe?
ReplyDeleteAha!
ReplyDeleteWell come on, what causes it??? You're killing me.
ReplyDeleteAs I said above, there is no 'right answer', only competing theories. I will say what my scientific friend thought later on, but there's mileage in this for a while yet :) The gentleman from Hull is on the right track, I think.
ReplyDelete'Fortean Times' runs an 'ice spike' picture and story seemingly every winter - you should send them the pics...
ReplyDeleteI'd better leave that to the copyright owner...
ReplyDelete"Any disturbed airflow is a source of drag."
ReplyDeleteTry telling that to Grayson Perry
You owe me a keyboard.
ReplyDeleteIt looks like the cross-piece should have been rotating at the time...so I'm guessing it's perhaps a roller for some sort of blind that runs up the angled beams and is currently retracted at the top of the picture. Water run-off as the blind was opened freezing as it gets thrown off the roller?
ReplyDeleteIt looks like a blind, yes, and also that the part carrying the icicles can rotate. I think that's the key, although I suspect the rotation was quite slow. How long would those icicles take to form, say on a dripping tap? Couple of hours?
ReplyDeleteLooks like a conservatory, so I'm guessing there is some contraption that automatically opens and closes the blind to regulate the temperature in the room.
ReplyDeleteAllow it to slowly retract the blind as the day ends and the temperature (otherwise) drops, and you make the cross-piece rotate slowly and create the icicles.
That's pretty much what my friend got. (And me too, honest, really.) The curve on the icicles is too regular, and to consistently replicated, to be the result of a chaotic factor like turbulent airflow IMO. It suggests a series of drips of water, falling off a slowly-rotating tube, although the rotation would have to be glacially (!) slow. Looking at the shape of the curves, I wouldn't be surprised to see a Fibonacci sequence in the maths somewhere. But don't take my word for it; I scraped O level Maths and failed Physics.
ReplyDeleteThe curve and replication remind me of Leg Iron's blog header.