frazil ice

Frazil ice refers to ice crystals or granules that form in turbulent water. This type of ice is almost always the first to form in rivers.12

Formation in Rivers

In rivers, the water temperature can drop below its freezing point due to turbulent mixing, a phenomenon known as supercooling. When ice particles are introduced, they cause further nucleation of ice. This process releases latent heat, bringing the water temperature back toward the freezing point, while ice production balances the rate of cooling.2

Frazil ice particles are typically small, often 1 millimeter or less, and disk-shaped. They can appear as thin sheets, slush-like masses, or dispersed particles in the flow. These particles can adhere to surfaces, causing issues at water intakes and forming anchor ice on riverbeds. Eventually, frazil pans can merge to form larger ice floes and accumulate upstream, creating an ice cover.23