Frost Flora

Posted On March 11, 2008

Filed under Uncategorized

Comments Dropped 9 responses

I appreciate all of your comments, it is nice to know that this blog is being read and enjoyed. Here, at the request of my sister Jeanne, the poet, is a description of how frost flowers form (WARNING TO READER: The following is not poetic!)

Frost flowers grow from water vapor onto new ice, nucleating in discrete “blooms” and then spreading out to cover the surface, if undisturbed. They form only when the conditions (relative temperature of water and air, humidity at the surface of the new ice, calm air) are right, because they require that the air immediately above the ice be supersaturated with water vapour. This happens when warm water is in contact with very cold air, and the evaporating water produces more water vapour than the colder air can hold. Thus, frost flowers are often found where cracks and leads have opened existing ice, allowing underlying (warmer) water access to the (colder) air and only a thin (new) layer of ice to separate the water and air. Thicker ice acts as an insulating layer and its surface is closer to the air temperature than to the water below.

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Frost flowers are typically dendritic or rodlike in form, similar to snow and hoarfrost. We see individual ‘trees’, with branches spreading outward, and ‘feathers’, which are flat with branches lying in a single plane. The individual branches have six-fold symmetry, like a snowflake.

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Snow also forms from water vapour, in the atmosphere of course, and generally on a nucleating particle such as dust. Water ice at typical temperatures and pressures is a hexagonal crystal, with a hexagonal basal plane, six-fold symmetry and growth favored in certain directions. Thus structures that grow from ice, such a snowflakes and frost flowers, tend to have hexagonal shapes or six-fold symmetry as well.

Frost flowers form only in low or no wind and are so delicate that the slightest breeze causes the larger ‘leaves’ to wave gently. Higher winds break them and carry them off, or bury them in snow. Collecting frost flowers has meant running a cold scalpel or spatula along near the surface of the ice, mowing them down like young trees and lifting them into a small container. Needless to say, this process breaks them up. Just the weight of more frost flowers added to the container breaks the lower ones, and of course they break more if the container is jostled in transport. (Never mind if it flies over a few bumps on a skidoo!) If not handled carefully, a full container at the collection site becomes half a container by the time it reaches the lab, proof that potato chip (crisp) bags may actually have been full when packed and “settled” in transport. (I know this has been the source of some debate.)

A highly saline brine also forms on the surface of new sea ice, and is wicked up by the growing frost flowers. Hence the frost flowers on sea ice are very salty. Because they are so delicate and so saline, they could be a major source of sea salt aerosol, which can be carried quite far by the wind. This is one of the reasons we are interested in them.

OK, Jeanne, your turn. I see so much here in the Far North that suggests poetry… the Northern Lights … more stars than you could ever count … a cold so sharp it takes your breath away … the snow blowing across the frozen bay, and the amazing waves left in its wake, the elusive red foxes that live on the sand dunes, the frost flowers themselves … all of it. But I couldn’t write a poem about it if my life depended on it. Can you?

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9 Responses to “Frost Flora”

  1. Jack Thomson

    Once again, Rachel, a superb description and excellent writing, which make frost flowers even more fascinating. What wonders there are!

  2. Sis

    Well that’s pretty poetic in my opinion!

    …How about a humorous haiku:

    Bring home from the bay
    frost flowers in a bucket:
    frost seeds now; sorry.

  3. Sis

    Another one:

    If no one hears the
    sound of sonde falling, did it
    take the measurement?

  4. Sis

    thwap!

    [sound of Rachel smacking Jeanne, long distance]

  5. Sis

    Okay, for serious, a poem for you:

    She Hears

    the skinny blue light that
    stalks the snow, and

    the frost-flowers at water’s edge
    with their six-fold hearts,

    and the borders of shadow
    gathered into a cove
    of fir and fox;
    she hears

    the sound the helix of green
    aurora wrings from the north sky, also

    like what the breath of the ice-bay
    says in the inuksuk’s ear, a

    crack

    of cold and distance.

    [dedicated to Rachel and Anita]

  6. evie obbard

    Dearest Rachel:

    Mary Ellen and I have so much enjoyed your Blog!! You have done a superb job in sharing your amazing adventure! We both think you are poetic!! All of your photos are magical!! What a great experience! I cannot say that I would truly enjoy popping off in the Arctic for a five mile journey! You both are very brave!!!

    I love you and miss you. Take care of yourself and I will call you when you get home. I have a special rate for the U.K.

    Lots of Love, Evie, Mary Ellen and Honey Fitz (her dog!!)

  7. Nick and Alex

    Aunt Rachel,

    Mom and I are so excited for you and your adventures. You are soooo cool!

    We were wondering if Gilbert is happy in his new home?

    Be Careful. Thank you for caring about our ice!

    love
    Nick and Al

  8. Mama Bear

    I like the pictures of the Frost Flower ‘rapids’ which look like aerial views of frosty froth rushing down a cold chasm. Makes me want a kayak. Or a really cooold drink. They are just beautiful. And so are your graphic descriptions. Your writing is so superb I can hardly believe you’re a scientist.

    I hope you are keeping your toes and finger tips warm. We await your return with bated breath.

  9. Stephanie

    Not a poet,Dr. Rachel?

    ” I see so much here in the Far North that suggests poetry… the Northern Lights … more stars than you could ever count … a cold so sharp it takes your breath away … the snow blowing across the frozen bay, and the amazing waves left in its wake, the elusive red foxes that live on the sand dunes, the frost flowers themselves … all of it.
    But I couldn’t write a poem about it if my life depended on it. Can you? ”

    Have read and enjoyed every word of your blog – thank you.
    Not only an accomplished scientist, you write from the heart.

    This section brought to mind early childhood memories of a Yorkshire home, without central heating, right on the snowline. The ‘frost-flower’ paintings (attributed to some artist named Jack Frost, by pure coincidence) which frequently decorated the window panes in the depths of winter were stunning.

    Thank you for the opportunity to share in your experience.

    Stephanie

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