What a happy birthday I had recently. I was lucky enough to catch the frazil ice collecting, breaking up, and re-coagulating in the Hudson River at The Glen while I was standing on the road within feet of where it was happening. It was a cold day, in the teens, but I have finally figured out how to dress warmly enough to stay perfectly comfortable for three hours.
For anyone new to my column, frazil ice is the “river ice” that looks a lot like slush as it floats down the river by the ton on cold days when it is not snowing. Frazil can start forming when the air temperature is about 25 F. if the water is already at 32, but the below 0 F. days were great for creating massive amounts, which fills the river starting at 1000 Acre Ranch 5 miles south of the Thurman bridge.
Frazil is most noticeable between Warrensburg and The Glen because roads go along the Hudson on both sides for much of the way. Some years the brilliant white ice has filled the river almost all the way to North River. Last winter was the first time the clogging reached only a few miles above Warrensburg. If this mild winter weather is a long-term trend, it may affect the renowned “ice meadow” plant community. On the other hand, it may not affect it, as long as high water flooding is as common as it is now; but a lot of us would miss the beautiful ice “canyons” that are left in late winter most years.
The tiny disk-shaped frazil ice crystals form in rocky, turbulent rivers where the cold air above the river gets mixed enough into the water to keep the water slightly below freezing (“super-cooled”) despite the heat which is released whenever a crystal forms and grows.