Last night (well, 0100 for me), the view wasn’t quite as spectacular, but it was still an interesting ride from the Bridge. We were in mostly pancake ice which doesn’t make any noise when it rubs along the hull mixed with some pretty good sized ‘growlers’, which do make noise when in contact with the hull. As a matter of fact, growlers can put a dent in our hull. I’ll get to that lesson later, but in the meantime I wanted to give beauty-credit to the artificial effects here. The ship’s lights are always on, so there are no dark decks. During the darkest hours, though, they run big spotlights off the bow and forward quarters to watch for threatening floating ice. The light from that beam that drops down on the snowcovered giant lilypads below, gives the snow a sparkle that reminds me of January in moonlight. It was mesmerizing.
There were science operations going on around 10 p.m. last night, including a haul by the Blake dredge that included a 300 pound rock! That rock so wedge itself into the front blades of the dredge (see the Auburn Univ. link on the WHOI web’s Antarctica page to see the shape it should be), that it bent the blades into a larger, not-so-flat-anymore opening. That poor puppy will have to be repaired before it will be of any use for a while.
Besides rocks on the bottom, there were hazards at the surface. I’ve mentioned the presence of ‘growler’ icebergs, and how they can be a problem. These large (up to 5 meters or so, then they’re officially “icebergs”) chunks of ice bob slowly at the sea’s surface. The lights pick them up very well, but if you see it when it’s down in the water, it might look fairly small. Look again, and it has risen high in the water showing it’s full girth! The helmsman must be very alert, and let other people on the deck know when there are ‘growlers’ coming into the path of the ship when operations are going on at the rear, and must change course slightly to stay out of their way.
Getting to Know …Your Ice
Definition of Iceberg: a large piece of ice that has broken off from a snow-formed glacier or ice shelf and is floating in open water. But, how did it get there, I wonder….
[the following is adapted directly from a Common Directory document on the LMG network, origin unknown by me.]
Development of Land Ice:
Water Vapor - crystallizes and becomes
Snow - A precipitation of ice crystals, most of which are branched
then there’s Firn - Old snow which has been transformed into a dense material. It is not snow; it’s particles are joined. It is not ice; it has communicating air interstices.
Ice Sheet - A mass of ice and snow of considerable thickness and large area on rock or floating on water. An ice sheet of greater than 50,000 square km is called an ice cap.
A mass of snow and ice continuously moving from higher to lower ground, or if afloat, constantly spreading.
Ice Shelf -
A floating ice sheet of considerable thickness attached to a coast. The seaward side is the ice front.
Ice Berg - A large mass of floating ice, more than 5 meters above sea level that has broken away from a glacier
Tabular Berg - A flat topped ice berg formed by breaking off from and ice shelf.
Bergy Bits - A piece of floating ice less than 5 meters above sea level and not more than about 10 meters across.
Growler - A piece of floating ice, smaller than a bergy bit, almost awash.
Development of Sea Ice:
Sea Water - (which on average, freezes at -1.9°C)
Frazil Ice - Fine spicules or plates of ice in suspension in water.
Grease Ice - A later stage of freezing than frazile ice
An accumulation of spongy white lumps, a few centimeters across formed from slush or grease ice.
Snow, saturated with water floating after a heavy snowfall
Ice Rind - A brittle, shiny crust formed on a quiet surface by direct freezing or from grease ice less than 5 centimeters thick Nilas
A thin elastic crust of floating ice bending on waves up to 10 centimeters thick
Pancake Ice - A piece of new ice approximately circular, 30 centimeters to 3 meters across, with raised rims. Formed from freezing together of grease ice, slush or shuga or the break up of ice rind or nilas.
Fast Ice - Sea ice which remains fast along the coast where it is attached to the shore; an ice front, ice wall or over shoals or between grounded ice bergs.
Pack Ice - Any area of sea ice other than fast ice no matter the form or disposition.
Floe - A piece of floating ice other than fast ice or glacier ice. There are five sizes:
Ice Cake less than 10 meters across Small : 10 to 100 meters across
Medium : 100 to 1000 meters across
Big : 1 to 10 kilometers across
Vast : Over 10 kilometers across
Ready for the Quiz??????
Back to the Science
I had the pleasure of assisting Susie Balser in the photo lab as she took microscope photos of some interesting plankton specimens. One of these that you've seen before, the pilidium larva that turns into a ribbon worm, was being particularly cooperative. We were able to watch, through the lens of the camera, a pilidium ‘give birth’ to a tiny ribbon worm!! Part of the ‘gut’ in that almost clear helmet-shaped larva, is really a tiny worm forming. Susie caught one whose worm juvenile (the larva is really the “baby”) was ready to crawl out of it’s developmental home. Over the course of about 45 minutes and several gentle phrases of encouragement (things like “come on, we’re friendly” and “if you come out, you'll be famous!”), drops of water to give it more ‘space’ to work in, and extreme patience, that little worm with his tiny yellow eyes (photoreceptors) and big goofy grin wriggled free of it’s shelter and went on its way (to get a job, I presume. This thing developed so quickly, I expect by this morning he was already going to college!).
Wait til you see this… you'll just want to name him and take him home!!!
The belief is that the larval housing will clone another worm rather than disintegrate. Stay tuned…
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S68° 18.208’ W68° 18.439’
Wind: ESE 12-15 kn
Air Temp: -1.5°C
Wind Chill: -13.5°C
Surface Water Temp: -1.717°C
Pork chops, meatloaf, mashed potato, asparagus, mixed vegs, rice, salad; Beef stew, baked cod, Brussels sprouts, rice, salad, banana bread, pineapple upside down cake, pudding and cookies.
Blake Dredge needs orthodonture. [Photo by Chris Mah]
Nice ‘Bergy Bit’ notice how much is ‘Pancakes’ mixed with ‘growlers’. [Photo by E. Bailey]
submerged. [Photo by Steve Alexander]
Dr. Susie Balser in the photo lab.
top: Stage 1
middle: Stage 2
bottom: Stage 3
[all 3 photos by Susie Balser]
Time to corral the pans again… [Photo by E. Bailey]
Stowaway Southern Fulmar on fore deck.
[Photo by E. Bailey]
N’ Iceberg in Marguerite Bay. [Photo by E. Bailey]