We had a few days of highs in the 50s followed by a very fast drop in temperature and moderate winds. So these crystals grew vertically in the ponded water and were then disturbed so that they were gouged out onto the surface or pushed up under pressure similar to needled ice. If you've seen this phenomenon before I would welcome a clearer explanation of their formation! I've read through this explanation of various ice habits but the actual physical control on formation isn't clear.
Friday, March 15, 2013
Winter Oddities: Prismatic Ice Crystals
Yesterday a student in my hydrogeology course brought these unique (to me) ice crystals to my attention. They formed in the middle of our on-campus hockey rink - basically a pond of water within a simple frame covered in Tyvek. I've seen needle ice, large depth hoar crystals, and hoar frost but I haven't seen crystals of this size. Many exhibit a euhedral hexagonal prismatic morphology - as both massive and individual crystals. Looking down on the surface of the ice it looks similar to a birds-eye view of columnar basalt exposures.