Ice, Ice, Baby

Rime ice that is.

In early January 2021 parts of Wisconsin was blessed with this wondrous natural formation. Specifically we got soft rime ice.

At first everyone was characterizing it as hoar frost, but it became such a news-worthy thing that meteorologists and other knowledgeable folks started correcting this assumption. Hoar frost formations are often different – more leaf or fern-like – and the occur through a different process as well. Rime ice, both the soft and hard varieties, forms when vapor in the air (mist and fog) condenses on objects then freezes. Hoar frost skips the condensing bit and freezes directly in the air.

Soft rime appears like little sticks or spikes and is also very fragile. It will blow off tree branches in a gentle breeze. Hard rime has to be knocked off. Both need temperatures at or below 17.6 °F, but soft rime only forms with little to no wind. Hard rime forms at higher temperatures (up to about 25 °F) because of wind chill and is more durable.

Another factor that contributes to hoar frost, but not rime ice, is radiant heat loss with accompanying humidity (but not fog!) – as the heat dissipates from objects their surfaces cool while inner areas remain warmer. The heat combines with humidity to immediately freeze in the air. The crystals adhere to whatever objects they came from. Because the surface is so cold, the ice crystals don’t melt, but pile one on top of each other in fabulous formations.

I’ve always said that fog is a photographer’s best friend, but so is freezing fog and that’s the big difference between rime and hoar frost – fog. If it isn’t foggy, it’s hoar frost. I have a streetlight in my driveway and I could see the fog in the air after sunset and knew we’d get ridiculously striking formations overnight.

So of course I went out just about every day which you can probably tell by these shots. The light was different each time and changed a bit on the day I hit the countryside.

All the farm shots were taken on the same outing. It was gorgeous and made me so happy I have this kind of rural beauty just a few miles from my house.

The sun came out for a little while and the blue sky created photos with a completely different feeling about them. There’s a lightness and cheerfulness that I think translates as simpler. There’s less to ponder while viewing a sunny picture versus a foggy or dark one. At least that’s how they strike me.

The blue skies were irresistible though and I’m glad I made the effort to get out and document this relatively rare event. It’s over now – having left as quietly and mysteriously as it appeared. Since the winter so far has been mild and unremarkable, this was a welcome phenomenon and can return any time.