Northeast Kingdom ice report, 11/29

[Evan Perkins]

I did a brief scout on my way home from Thanksgiving travels. I found that Keiser pond on Harvey's hollow rd in peacham had a little more than 1/2 inch of ice over a little bit more than an inch of slush with a very thin, perhaps quarter inch layer of clear ice underneath. I also saw several other small swamps and bodies of water that were covered in slush. The pond had about 3/8 and inch of snow on it that had wetted through in many places. Temps are going down near 20 tonight and not too much above freezing tomorrow. Slush that is sandwiched between two layers of ice like this tends to freeze at a faster rate than slush that is just floating on top of water. In my experience, it freezes about a third faster than what you would expect given normal freezing degree day calculations. I expect this pond will be probably about 2 inches thick by Sunday morning, maybe a little more if we're lucky.

  I have included two pictures below, one is a sample of this ice being held upside down with the smooth ice that was resting on the water facing upwards .you can see the layer of slush in between and the half-inch plus of frozen slush, which made up the surface.

   The other picture shows the bottom layer made up of small grain ice crystals. as this lake continues to freeze, it will freeze with small grain ice, which is generally weaker than large grain ice . that being said when small grain ice is new and below freezing, it is often only 15% weaker than large grain ice.(for those who don't know, small grain ice is weaker because it is the crystal boundaries that are the weakest part of the ice pack, meaning the smaller, the grains of ice, The more crystal boundaries present in a square foot of ice. when these boundaries are frozen solid, this ice is still very strong, the big danger comes after freeze thaw in cycles where small grain ice can diminish in strength down to only 30% of large grain ice as these crystals boundaries break down. Under extreme conditions, small grain ice can diminish to be even weaker than that, meaning that you could fall through Ice that was six or 10 inches thick. Not something to worry about when it's cold but good to keep in mind for spring ice)

    Even though this is just one small pond in the Northeast kingdom, I assume there are many like this with similar conditions all across northern Vermont, New Hampshire and Western Maine.