A second round of frostweed ice this season

After I awoke yesterday morning and saw that our outdoor thermometer showed exactly 32°F (0°C), I knew that after the sun rose I’d be heading down to Great Hills Park to find out if the frostweed plants (Verbesina virginica) had gone through a second round of their famous ice trick. The view from where I parked didn’t look promising, but once I walked down the slope to the frostweed plants, I saw that there’d be enough ice to work on. In fact I ended up spending a little over three hours there.

I took the third picture at almost 11 o’clock, when the temperature
had risen to 45° and the frostweed ice was slowly melting.

If you’re not familiar with this unusual phenomenon, what happens is that when the temperature drops to freezing the frostweed plant draws water up from underground via its roots and extrudes it through the splitting sides of its stalk as delicate sheets of ice, mostly close to the ground. You can learn a lot more about the science of frostweed ice in an article by Bob Harms.

© 2020 Steven Schwartzman