Needle ice – an anomaly in the dead of winter
Wed, 01/18/2023 - 9:28am
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By:
Frank Conway
“What in the world?” my father-in-law asked as we pulled into his driveway last Christmas Eve. Having built the house half-a-century ago, he quickly noticed that something didn’t look right around the family home. An out-of-place shimmer in the front yard had caught his attention. It caught mine, too. It appeared that an area with little to no grass had suddenly sprouted a miniature lawn of ice. I don’t mean that there was ice covering the ground. I mean that there were vertical blades of ice “grass” shooting up out of it and I had never seen or heard of anything like it before.
One of the downsides of being an engineer, whether by degree, profession or just by inclination, is an insatiable desire to understand the “why” of things. I definitely did not understand this icy “grass” and a couple of hours of my Christmas Eve were consumed with figuring it out. I tend to focus on the negative societal impacts of the internet and social media, but Google can occasionally be my friend. As I went from site to site, I began to understand the magnificent ice “lawn” that had established itself in the front yard overnight.
Needle ice is one of several fascinating ice anomalies sometimes found in our natural world. Rabbit ice, frost flowers and frost ribbons are other rare displays viewable via easy online searches and requiring very specific environmental conditions to form.
Needle ice requires porous soil with a high moisture content, unfrozen ground and sub-freezing air temperatures. A physical phenomenon known as capillary action pulls moisture upward through narrow channels or tubes to the surface where it freezes. As more moisture follows from below, it also freezes and forces these tiny tubes of ice upward, overcoming gravity in the process. The result looks much like icy grass, except that there is no grass inside. The tubes are free-standing, self-supporting and absolutely beautiful.
My father-in-law’s needle ice formed where a load of topsoil with a high clay content had been spread several months earlier. His neighbor had taken delivery of some of the same soil and had the same result. The remainder of their yards produced no needle ice at all. With some tubes as long as 2-3 inches, the fields of ice needles were hard to miss.
Now you know what needle ice is, but don’t expect to just find some outside the next time we have a freeze. I spend a lot of time outdoors here and I think last Christmas was the first time I had ever seen it. Perhaps it is more frequent in colder climates. That seems likely, but somehow I just can’t see myself moving north to find out.