These interesting cousins of crop circles have intrigued me lately, when they show up overnight.
If you look closely at the photo to the right, you can see the culprit ~ our tank heater!
Lately, the weather has been very
un-winter-like, and the "Cs" show up when the trough heater doesn't have much work to do.
In the photo to the left, you can see what causes the "C" shapes, and in the photo below...
...you can see the "C" shapes are actually made up of tiny bubbles.
My husband insists the bubbles clearly show the cause of these "mysterious" symbols is simply localized boiling, just above the heating elements.