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February 18th, 2004


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01:22 am - eh
Hmm....I really should be working on studying for two tests next week, but....eh. I'll do it tomorrow.









Thin sheets of water flow down....some of it freezes and the rest just drips from the tip. As this happens over and over again, the icicle becomes longer and longer. After a while, it develops ridges. If you look at those little ridges, you can see that they're really pretty evenly spaced (8mm, as it turns out). So, I've been wondering what the hell causes those ridges.

I've found two explanations in my search online to explain the spacing of those ridges.

The first has to do with gravity pulling downward on the water as the surface tension pulls in the opposite direction (as we see with water dripping from a pipe, or some such). I've never come across any source supporting this explanation with any sort of in-depth explanation, however. Maybe it's just that my searching skills are not up to par.

The second explanation is newer, I think....and probably a lot better. I can't express it very well, unfortunately, but I will try.

In order for ice to form, we have to remove heat from the water. It turns out that heat is more efficiently removed from the peaks of the ridges on the icicles than the valleys. Those peaks initially formed on top of very small concavities in the ice as it was forming. These things occur randomly.

As this is occuring, a thin sheet of water is continually running down the surface of the icicle, yes? If the wave pattern of the ice is not efficient for removing the heat from the water in order to freeze it, the flow of water will just naturally fill in the wave pattern until a pattern develops that is more conducive to the process.

As it turns out, these two opposing processes balance one another out in such a way that the spacing is always even (8 mm). Pretty neato. I'm sure that this is a GROSS oversimplification of a very complicated process....but it's probably way over my head, at this point in my studies.

This theory also states that as the icicle grows in length, the ripple pattern will migrate down the length of it at half the speed of its growth. If I had a stop-motion camera, it would be fun to see if I could capture that process. Manhattan, KS is such a freaking winter wonderland lately, it would provide a good opportunity, eh?

Anyhow...that's a simplified explanation, as best as I can get it. It's a very complicated process, but at some point in the future, I hope to gain a deeper understaning of it. Hopefully tomorrow, I'll be able to do some more digging around in the journals at the library.


http://www.aip.org/enews/physnews/2002/split/613-2.html
http://www.physics.utoronto.ca/~smorris/edl/icicleripples/icicleripples.html


Current Mood: sleepysleepy
Current Music: static in headphones. :(

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