I took this shot a couple days ago on my way to the mall, thinking it would make a nice Facebook cover photo. Having grown up in a house without a clothesline, I noted that it seemed strange that someone would be hanging clothes out to dry in sub-freezing weather. Wouldn’t the clothes freeze and not dry on the line?
There were a couple of Facebook comments along the lines of, “I thought they were cows going into the barn, not clothes! LOL!” But my nephew, Greg, and brother-in-law, Bill, both mentioned sublimation, and that, yes, the wet, frozen shirts and pants on the line would indeed dry in the midst of a long, cold Syracuse winter.
Hmmmm, I thought. Really? Thinking back to high school science class (I’m not sure if this would be Earth Science or Chemistry), I only remembered sublimation involving dry ice (frozen C-O2) which went directly from a solid to a gaseous state without any real liquid to worry about. And that was only because room temperature was above the boiling point of C-O2. How could frozen H2-0 disappear into thin air when the air is cold enough for it to stay frozen?
It turns out Greg and Bill are right (no surprise). Ice in below freezing air does indeed slowly turn from a solid to gas without needing to pass through a liquid/melting state. And, ta-da! Dry clothes!
Wikipedia entry: Sublimation
And yes… I guess they do look like cows.