Our birdbath contained an unexpected and surprising structure on a recent January morning with freezing temperatures and near-constant overnight winds. The structure consisted of a finger-like structure pointing at an angle of about 30 degrees of elevation in the general direction of the prevailing wind. The structure seems to have grown out of the water with no visible means of support other than from the ice itself. I believe it formed from the prevailing wind forcing freezing water to the base of the growing (freezing) structure under the influence of the symmetry of the birdbath, and I visualize the structure “growing” out from the ice base overnight as the freezing process collected more and more freezing water as ice.
Thorough science-based explanations for this event are invited, and I will entertain all theories with interest.
Explanation for identity and mechanism of formation received via Nikon Cafe website: