“Frost flowers” in Arctic and Antarctic seas can form on a calm ocean surface when very dry air is much colder than the water. Let’s look at this supercool phenomenon.
Are they real flowers?
No. They are called that because when thousands form on a still expanse of water, they look like flowers in a meadow. Kind of. Individually they look more like chaotic 3D snowflakes, about an inch or two across.
What kind of conditions are required for frost flowers to form?
The air must be both very dry and much colder than the water’s surface — about minus 7.6 degrees Fahrenheit.
How do they form?
When ice sublimates, it changes from a solid directly into a gas without stopping to be a liquid. If that vapor becomes oversaturated with liquid, it reverts to ice as soon as it touches an ice crystal. As this keeps happening, the flowers grow.
I thought salt water doesn’t freeze as easily as freshwater. Are frost flowers salty?
Ocean water freezes at 28.4 degrees Fahrenheit, about 3.5 degrees colder than freshwater. In an ocean environment, frost flowers are almost three times saltier than sea water, because as they form, a process called brine rejection forces salt out of the porous sea ice, and up into the flowers.
Does anything live in frost flowers?
Surprisingly, yes. When researchers let a frost flower melt, they ended up with about one-quarter to one-half a teaspoon of water. That tiny puddle contained about a million bacteria! What’s weird is that they were thriving in an environment much colder, brighter, and saltier than what they’re used to.
Are frost flowers becoming rarer?
On the contrary. Biological oceanographer Jody Deming, a professor at the University of Washington, expects to see more frost flowers as the poles warm, because there will be bigger expanses of Arctic water turning icy in wintertime.
By the way, if you aren’t planning a trip to the Arctic this winter, check out your freezer. The frost in there, also known as hoar frost, forms pretty much the same way that frost flowers form. It’s just not as cool.