The Midnight Diaries of Catty Wampus

I couldn’t believe my own eyes the first time I saw this phenomenon. I had never heard about it, never read about it, never thought it was possible–and yet here it was happening, right in my very own freezer.

MY ICE CUBES HAD BECOME…. *ahem* AROUSED!!!

I had only moved into my apartment a few weeks earlier. It was the first time I’d ever lived alone, so I had gone out and bought a bunch of little household items for myself; a water pitcher, and ice cream scoop, soap dishes, ice trays.

(This is something they never tell you about when you move out on your own, by the way: all the little stuff you’ll have to buy–and it gives you a shocking feeling of “growing up” to actually own your very own soap dish. Two of them, actually: one for the kitchen and one for the bathroom. It’s an entirely different feeling from the larger items, like pots and pans, or lamps and bookshelves.)

The ice trays were your standard plastic Rubbermaid products. You fill ‘em with tap water, stick them in the freezer, and in mere hours you have cubes of ice ready to pop out of the tray and into your favorite refreshing drink. Or your soup, if it’s too hot. Or your kitchen floor, if you haven’t quite got the hang of bending the tray just right so the ice doesn’t fly out in all directions. (it’s been seven years and I still haven’t got the hang of it)

So that’s just what I did. I filled up my ice trays with water and let them sit for about a day in the freezer. And much to my surprise, when I went to retrieve some ice for my water on a balmy summer’s day, I found that every fourth cube or so had grown a spike of ice–from the ground upwards! Some cubes were more well-endowed than others (to parallel human biology), and some had no activity going on in their chambers at all (to parallel human society).

When you see an icicle on the eave of your roof, it has formed because a small bit of water has frozen in place and more and more water has run down its side and frozen before it can drip off of the bottom. Gravity plays a large part in the formation of the typical icicle, you see. What was baffling was that my inverted icicles seemed to be defying gravity!

It wasn’t a one-time occurrence, either. My ice would perk itself up again and again, with each new batch. I would invite my guests to have a look inside my freezer to witness my ice cube trays. Most were as astounded and as baffled as I was. No solution seemed apparent. There was no water dripping from the freezer’s ceiling. The bottom of each ice tray, as well as the freezer’s surface, was smooth and free of bumps. What, then, could be the solution?? Was I living at the nexus of some kind of cosmic wormhole where Newtonian physics ceased to operate?!?!?!?

No, not at all. It took four years, but a friend of mine found an answer online.

It turns out that this phenomenon, while not widespread, is also not uncommon. As I understand it, it happens like this: When ice forms, it forms freezes from the outside to the inside. That is to say that the edges will become ice before the center does. (like when you see an ice-covered lake, but the fish and plants still live in the unfrozen water below) The final part of the ice’s surface to freeze is the very center. Now, when ice freezes, it expands. This creates pressure–specifically, pressure upon the inside of the ice cube, which is the water that has yet to freeze. With solid ice all around, the water has no choice to go towards the only area open to it: the nearly-frozen space in the top and center of the ice’s surface. The pressure pushes the water further and further upwards (with the outside still freezing quicker than the inside) until the entire thing is frozen and what is left is a spike of ice reaching for the sky.

Interestingly, I never would have learned this if I had bought metal ice-trays. You see, it only works in plastic ice trays because the plastic is much more accommodating to the pressures of cold temperature and freezing water.

Stay tuned for future episodes of It’s Science!