Your turkey isn’t the only thing that has beautiful plumage this Thanksgiving. So does the Arctic Ocean. Behold, the frost flower.

These spiky little bunches of ice form on thin and new ice in the Arctic Ocean. But these badboys can only form under very special conditions:

1) Calm winds. We can’t have these beauties blown away can we?

2) Cold, cold air. It has to be about 20C less than the water and since seawater freezes around -2C, that means the air must be about -22C or -7.6F. BRRR.

Frost flowers form when newly formed ice sublimates, that is ice changes directly from a solid to a gas totally bypassing the liquid stage. Initially, the water vapor formed by sublimation is the same temperature as the sea ice, but gets quickly cooled by the cold air. The air is then becomes supersaturated with water vapor, which means the air has too water much in it. Air really doesn’t want to hold all that excess water vapor, so when the supersaturated air touches another ice crystal the water vapor quickly turns back into ice. This process is called nucleation, on little chunks of ice that are sticking up out of the water or even ice crystals floating in air. Over time, more and more crystals form on existing ice. The crystals expand outward in spiky arms, creating the little punks we know as frost flowers. Frost flowers are found in the Arctic, the Antarctic and even grow on freshwater ponds.

But in the ocean, frost flowers have a really unusual characteristic. Unlike normal ice, which is extremely fresh, frost flowers are salty. The porous sea ice on which frost flowers form squeezes out salt water in a process known as brine rejection. Frost flowers wick up the salty brine onto the crystals, causing the salinity of frost flowers to reach 100 psu, nearly three times the salinity of sea water! Perfect for pickling.

I’ve never seen frost flowers in the wild. But you don’t have to go all the way to the poles to see beautiful ice. Just look in your freezer to find a close relative of frost flowers, hoar frost. You just might call it “freezer burn.”

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UPDATE: I’ve gotten a lot of questions about how large frost flowers really are. They are only about 3-4 cm or 1-1.5 inches across. Pretty tiny.

I’m not actually a frost flower researcher, I just found out they existed and wanted to share them with the world. To learn more about the effects of frost flowers there are great articles by those that study them and took those pics here http://schaechter.asmblog.org/schaechter/2011/05/frost-flowers-come-to-life.html and here http://students.washington.edu/bowmanjs/wordpress/?p=106

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UPDATE 2: Apparently I am not the only person that likes frost flowers. Several of the commenters there had more questions about frost flowers, which Jeff Bowman tackles here at his personal blog: http://students.washington.edu/bowmanjs/wordpress/?page_id=68

REFERENCES:

Style, Robert W., and M. Grae Worster. “Frost flower formation on sea ice and lake ice.” Geophys. Res. Lett 36 (2009): L11501.

Rankin, Andrew M., Eric W. Wolff, and Seelye Martin. “Frost flowers: Implications for tropospheric chemistry and ice core interpretation.” Journal of Geophysical Research 107.D23 (2002): 4683.