frazil ice in Yosemite National Park

Steven Bumgardner, who produces Yosemite Nature Notes for the National Park Service, shot some video of "frazil ice" on the Merced River in the park this week, as a cold early spring storm moved across California.



I'd never heard of frazil ice before. Now, because I must look things up compulsively, I'm learning about it. Wikipedia says, "Frazil ice is a collection of loose, randomly oriented needle-shaped ice crystals in water. It resembles slush...," which probably explains why I'm imagining margaritas. And Hajo Eicken at the Geophysical Institute at the University of Alaska, Fairbanks, says

The word frazil means fine spicules or blobs, which gracefully describes the morphology of the crystal. Sea ice growth always begins with frazil ice production, the only true dendritic ice growth phase. Active convection aids sensible heat transport at the ocean surface, thereby super cooling the water and allowing dendritic growth of ice crystals.

This is so cool. Spicules and blobs. Scientific terminology rocks. ("Dendritic," of course, means it's like branches of a tree, like drainage in a river delta, or the shape of a neuron.)

The waterfalls of Yosemite must be delightful just now.