Each time we send out a newsletter, maybe 300 people look at the What in The Woods is That picture, between 50 and 100 regularly venture guesses, and about a half dozen send us in-depth answers that offer interesting insights. Reader John Patterson shared this about last week’s hoarfrost picture:
“I live on a pond in Southwest New Hampshire and have had some experience with this phenomena in the last 30 years. It is a form of rime or hoarfrost, which in my experience requires rather exacting conditions, namely, at least single digit temperatures, a perfectly still night, and just the right humidity. I find it curious that it extends not more than 30 feet back from my pond’s edge, maybe reflecting some subtle change in temperature or humidity in that distance, perhaps reflecting a little less radiational cooling of the supporting surface below the sub-freezing dew point, back in the shelter of taller trees.
The pond seems to influence hoarfrost even when the pond surface is locked in ice and covered with snow. The crystals precipitate out of the atmosphere on any surface surrounded by air: needles, twigs, weeds, even other ice surfaces. As the picture with my hand for scale shows, while the structures can achieve considerable size and apparent fluffiness, they remain remarkably delicate and fragile. The least stirring of a morning breeze or a puff of your breath shatters them to sparkle in the morning sun like flakes of mica.”
The ephemeral nature of hoarfrost is especially resonant. One moment it’s there, the next, it’s gone. This impermanence feels important. It’s another example of how the natural world just pulses with beauty - a bobcat flashing through a fir thicket, an unusual cloud formation trolling through a Bahamian blue sky - fleeting images that are there for the taking if you’re in the right spot at the right time.
Do other readers have photographs of unusual frost formations? If so, I’d love to see them.
Discussion *