Winter in Minnesota can be a challenge, but it can also be gloriously beautiful. This year we have been blessed with a stretch of above-normal temperatures that have created the perfect conditions for hoar frost, almost on a daily basis. We even had rime ice the other day, which is quite possibly my favorite winter phenomenon.
Hoar frost, and the closely related rime ice, always remind me of the book "Horton Hears a Who!" by Dr. Seuss. We are able to see, just as Horton was able to hear, something that is typically hidden from vision, namely water vapor.
Hoar frost is an impossibly thin layer of ice that forms when water vapor in above-freezing air comes into contact with an object whose temperature is below freezing, transforming the vapor to ice. It looks as if the entire landscape has been sugared or sprinkled with diamond dust. Clear, still mornings are usually best; wind and the warmth of the sun quickly cause the effect to melt away. I like to imagine Mother Nature blowing a gentle, warm breath slowly across the landscape, releasing it from its icy grip.
Why the peculiar name? Interestingly, this usage of the word "hoar" originates in Old English where it was defined as "showing signs of old age". Apparently people thought the frost made the trees resemble the beard of an aging man. I guess I can see it, but it always strikes me as an amazingly inadequate representation, completely missing the magic and beauty.
Similarly, rime ice, which looks like an exaggerated version of hoar frost, forms due to this supercooling of water in the winter air. The difference with rime ice, technically, is that the water vapor first condenses into liquid droplets and then attaches to a below-freezing surface. Fog in the winter is often a good indication that there will be rime ice (and also that I will be outside in boots and my pajamas). Visually, the effect is absolutely stunning. Rime ice is much, much thicker than hoar frost. You can see the individual ice crystals, frozen in time, stretching up into the air.
Rime ice also takes much longer to dissipate, much to my delight. Instead of simply vanishing, the fluffy ice crystals float down, like a soft snowstorm in a sunny sky. It's like stepping out into a snow globe (but this "snow" doesn't need to be shoveled). It can take hours, and transports me to my child's mind, lost in the wonder off it all.
The most beautiful thing about hoar frost and rime ice is that they cause one to pause. Unlike snowfall, they don’t mean snowy roads and shoveling. They are Mother Nature’s ode to the beauty of winter. Instead of rushing from one thing to the next, or one thought to the next, for a brief moment you can be still and present in the beauty of it all. You actually see the trees and foliage that you normally just walk or drive by. Maybe, like Horton, you’ll see something you’ve never seen before. And what is more beautiful than that?