Tag Archives: melting

Writing prompt: The Melt

Time: 7 minutes. Click here to go to my list of prompts.

“The Melt”

Elijah strapped the packages and foodstuffs to the sleigh. When they were secured, he went and fed the dogs. It would be a long day for them tomorrow. It was the hard time of year. It was time for the Melt. Each year their small community packed onto sleds to escape the floods of the spring melt. One who left too early faced oppressive cold and winds in the high country. One who left too late faced mud and run off and risked the sudden floods. This winter’s weather had been tumultuous, and Elijah felt uneasily that they might both be too early and too late. This year, perhaps nothing would be right.

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In the morning, Elijah and his neighbors left their communal home. It would not be there when they returned. Ahead of them stood miles of whiteness, the great fertile flood plain. The world was silent but for the creaking of the ice under the sun. All day long, the dogs pulled the sleds. Elijah and the stronger men and women skied alongside the sleighs. The children and the elderly rode the sleighs.

Late in the afternoon, the party came to a river.

“This ice is no good,” Elijah’s sister Elta said. “Look, cracks run deep into it, and the color is not right.”

“I said we left too late,” someone said.

“We’ll have to go around,” Elijah said, trying to force an air confidence he did not feel. “This has happened before.” It had happened before, but never without death and suffering. The fickle sun shone down, weakening the river further.

Fun science: how does figure skating work?

How does figure skating work? In short, we don’t fully know. You may have learned in science class that the pressure of the blade causes the ice to melt. Water does have the unusual property that solid ice is less dense than liquid water, and ice will melt under sufficient pressure. The thing is, the weight of a human body on an ice skate isn’t enough pressure to induce that melting.

Phase diagram for water. At normal atmospheric pressure, water freezes (to ice I, or normal ice) at 32 F or 273 K. At higher pressures, the freezing point is suppressed, as shown by the solid black line between the blue and white regions at the bottom. (Figure credit, Wikimedia)

So, if not the weight of the skater, what allows the blade to slide along? Well, there is a layer of liquid at the interface of the blade which allows the skater to glide. Denizens of very cold climates know that at sufficiently cold temperatures, skates do start sticking and catching on the ice (source: my mom’s many winters in Wisconsin, and science). Our best guess right now is that the surface properties of ice differ from the properties of the bulk. Perhaps at the surface of ice, the pressure *is* sufficient to cause melting (at temperatures near enough to freezing).

The difference between bulk properties (the properties of a big chunk of something) and surface and scale-related properties is increasingly studied. Nano-scale gold exhibits a wide variety of properties depending upon particle size, as you can see in the image below. Such colloidal gold is used in a variety of medical applications such as tumor detection and drug delivery.

Solution colors change as the gold particle sizes change. (image source Wikimedia).

When things like water and figure skating are still mysterious, who says science doesn’t leave room for wonder? Given the relatively few forces interacting in such systems, I find the richness of variation we observe entrancing. This Olympics, I’ll watch the athletes skate and consider the angstrom-scale world on which our lives glide.