It’s November now, which means we’re edging into winter, and my morning ritual has been expanded to include scraping the frost off the cars when I get back from walking the dog. I’ve had to do this half a dozen times already, and I’ve noticed a puzzling pattern.
Our driveway is aligned almost exactly east-west, with the cars facing east when they’re pulled in at night. This means that one set of side windows faces north, and the other south. And here’s the thing that puzzles me: the frost layer is significantly thicker on the south-facing side windows than on the north-facing side windows. I have to actively scrape the south-facing windows, but the north-facing ones I can just about wipe off with my hand.
I have no idea why that should be the case (the cars are symmetric under reflection about the axis, after all), but it’s very repeatable. But then, I’m not all that clear on the science of frost formation in the first place. I’m sure that some of my wise and worldly readers know more about weather-related matters than I do, though, so maybe one of you can explain it to me. Why do the south-facing car windows collect more frost than the north-facing car windows?