Frosty Flowers Cover Boysen Reservoir Like A Sea Of ‘Sagebrush’

Deanna and Ed Reish were taking their 6-year-old grandson McCrae Puckett on his first ice fishing experience on Boysen Reservoir recently when they found something they hadn’t seen before — a field of frost flowers covering the crystal-clear ice of the lake.

“I kept looking out at the lake and I was like, ‘That looks weird,’” Deanna told Cowboy State Daily on Tuesday. “It looked like these round things were all over. We thought it was snow, then once we got out of the truck, these things were all over the ice.”

The crystal-clear ice was covered with clusters of large, delicate ice crystals. It was like a vast expanse of white sagebrush stretching as far as the eye could see.

“Our grandson tried to pick some up for me,” Deanna said. “He said, ‘I want to give (Grandma) a rose.’ So, he would bend over and try to pick them up off the ice, and they would just crumble apart.”

The Reishs were surrounded by delicate frost flowers for the entire fishing trip. Soon after, they were gone.

“I've been ice fishing since I was a little kid back in Minnesota,” Deanna said, “and then a lot out here (in Wyoming), and I've never seen anything like it.”

Frost Flowers

The Reishs witnessed a frozen phenomenon called hoarfrost, which can create dramatic ice crystals and buildup on almost anything in cold climates. But unlike icicles, hoarfrost requires specific conditions to form.

Hoarfrost forms when the winter air is saturated with moisture, but no strong winds are blowing. In these conditions, the moisture in the cold air immediately forms an ice crystal when it contacts an object rather than forming a water droplet.

Cowboy State Daily meteorologist Don Day knows Boysen Reservoir as a natural place for those atmospheric conditions.

“Boysen (Reservoir) is an extremely cold place,” he said. “It’s a low point where a lot of cold air will drain into. There are the kinds of temperatures that would certainly support that kind of frost growing.”

As Deanna found out, hoarfrost can be incredibly photogenic, but it isn’t free-forming.

“Frost like that needs a surface,” Day said. “It needs something for those crystals to grow on. I don't know if it was a bump in the ice or something that made those ice crystals form in that pattern, too. Where there were these little pods everywhere, there was something they had to adhere to.”

That’s just the tip of the iceberg — or the top of the perfectly clear ice sheet.

Fertile Fields Of Frost

Deanna Reish said she and her husband learned the solid ice sheet they were on formed relatively recent to their Jan. 5 fishing trip.

“My husband said one of his co-workers had talked to the park ranger,” she said. “And they said the lake froze in that area between Christmas and the 5th of January when we were there. It was fairly new ice, about 8 or 10 inches thick. But it was just crystal clear.”

Clear ice forms when water freezes slowly without ice crystals and debris. If more snow falls on top of the ice, it loses its transparency.

The new ice could explain the field of frost flowers. Hoarfrost only forms crystals like that on freshly frozen ice, adhering to the imperfections on the surface, Day said.

The only imperfection in that explanation is the thickness of the ice. While the ice on Boysen Reservoir was thick enough for ice fishing, hoarfrost usually indicates it's too thin to step on, let alone cut into.

Frost Flower Fishing

Regardless of the circumstances, the frost flowers on the frozen Boysen Reservoir resulted from several specific factors coming together to create a visually striking sight. But that sight didn’t last long.

The Reishs were among the handful of people recreating in the area that morning. When she posted the photos of the frost flowers to Wyoming through The Lens, many other people decided to go see for themselves but were disappointed.

“There was nobody else around,” Deanna said. “People commented on my pictures and said they wanted to see them. Then other people tried to go see them, but I think it probably covered him up not long after we were there between the winds and some snow.”

Deanna said she held off on posting the pictures immediately, thinking the frost flowers weren’t so exceptional. Instead, dozens of people said they’d never seen anything like it, particularly on Boysen Reservoir.

As for the fishing trip, Deanna said everyone left ecstatic.

“Our grandson caught a really nice rainbow trout and a nice walleye,” she said. “And then my husband got a nice perch … oh, a ‘giant’ perch, he says.”

Andrew Rossi can be reached at arossi@cowboystatedaily.com.