"Frost flowers" are "a strange phenomenon where frost grows from imperfections in the surface ice amid extreme sub-zero temperatures nearing -22C or -7.6F, forming spiky structures that have been found to house microorganisms. In fact, the bacteria found in the frost flowers is much more dense than in the frozen water below it, meaning each flower is essentially a temporary ecosystem, not unlike a coral reef."
The cold, moist air above the open cracks becomes saturated and frost begins to form wherever an imperfection can be found on the ice surface. From these nucleation points the flower-like frost structures grow vertically, quickly rising to centimeters in height. The hollow tendrils of these “frost flowers” begin to wick moisture from the ice surface, incorporating salt, marine bacteria, and other substances as they grow.More details (and additional photos) at Colossal, via allhomosapienswelcome. Unlike the land-based "frost flowers" I used to see when I lived in rural Kentucky, these Arctic ones are truly made from frost, not from extruded ice.
Reposted from 2012 (!) to add this image of frost flowers seen on Lake Harriet (Minneapolis) this week:
"These delicate clusters of ice crystals can form on top of newly frozen ice only when it's very cold and the air is very still. Frost flowers are more commonly found on fresh sea ice, but can form on newly frozen freshwater lakes. They do not last long and are damaged by wind.It's been has been years since we’ve had anything close to the right conditions for frost flowers like the ones that formed yesterday. The ice must be very fresh so it is still close to the water temperature and the air must be at least 20 degrees below freezing and the calm for crystals to form."
They look like fractals, kinda like snow flakes but much bigger.
ReplyDeleteFractals are a form of unstable crystal growth. Normally, crystals grow slowly by adding molecules to the slow-growing surfaces of the crystal. Thing quartz crystals, or simply crystal sugar. For such crystals, the movement of new material to the surface is the rate determining factor and low.
However, sometimes, when you have very high concentrations of material surrounding your crystal, you can get fractals. In this case, the material is already there, so transport can not be the rate determining step. What then happens is that the concentration of material near the surface is a little lower than the surrounding area, because those molecules just crystalized. But any small bump will poke through that layer into the higher concentrated area and grow super fast.
That's how you get all the little arms.
I can imagine such conditions exist when you have very cold water (that basically should have frozen already) near saturated air.....
https://www.flickr.com/photos/gripspix/2149282486
Deletehttps://pixels.com/featured/fractal-frosty-ice-crystals-kent-lorentzen.html
This remined me of something I find occasionally when hiking in he Appalachian mountains, especially on cold mornings. I always called it 'rime ice' but the Great Google in the Cloud tells me I was mistaken and 'rime ice', while also amazing, is another thing entirely. It is actually 'needle ice', and when found along the edge of a trail when the ground to one side is rough and much higher than the trail, needle ice can do some amazing things.
ReplyDeleteI don't have a photo but I found this:
https://nhgardensolutions.wordpress.com/tag/white-puddle-ice/
About 2/3rds of the way down, or search for 'needle ice'
I remember occasionally seeing that needle ice when I lived in Kentucky.
DeleteI too have seen 'needle ice'. Usually, it is mud that has been extruded out of the ground by vehicle tracks or footsteps during the day, followed by a good frost overnight. It's like the cold sucks the water out and freezes it?
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