Frazil Pan Ice
I love it when the Tanana River [TA-nuh-nah] freezes up this way.
Certain conditions must occur for this kind of ice to form; water must be moving, and supercooled (30° to 21°, -1C to -6). Water begins to form ice crystals, which gather in 'rafts' that spin and bump in the currents, forming pans with slightly rigged edges where they jostle into each other.
As this kind of ice progresses, the pans become larger, thicker, taking over the entire surface of the river. As this happens, the river becomes 'vocal', making shushy-whispering sounds as the pans jostle and bump.
As temperatures get colder with winter's progress, the pans eventually become so congested that they become fast and form an unmoving solid and jumbled surface on the river.
Frazil Pan Ice
I love it when the Tanana River [TA-nuh-nah] freezes up this way.
Certain conditions must occur for this kind of ice to form; water must be moving, and supercooled (30° to 21°, -1C to -6). Water begins to form ice crystals, which gather in 'rafts' that spin and bump in the currents, forming pans with slightly rigged edges where they jostle into each other.
As this kind of ice progresses, the pans become larger, thicker, taking over the entire surface of the river. As this happens, the river becomes 'vocal', making shushy-whispering sounds as the pans jostle and bump.
As temperatures get colder with winter's progress, the pans eventually become so congested that they become fast and form an unmoving solid and jumbled surface on the river.