Wednesday, January 8, 2014

Watching the Frazil Form

Well, if I had to get sick, this was a good week to do so, with weather so awful I wouldn't have gone outdoors anyway.  First, we had rain to turn all our lovely snow to slush.  Then arctic cold slammed down to way below zero, turning that slush into slippery slashing blades underfoot.  Then the wind came howling to drive that cold down deep in your bones, no matter how you bundled against it.  Yes, a good week to curl on the couch with a Kleenex box, mugs of hot tea at hand, and laps full of furry cats.

Today, both the cold in my head and the cold outdoors eased up enough to tempt me out under a clear blue sky.  But just for a drive.  The frigid air still caused me to cough with every breath.  It was only in the single digits above zero when I headed up north, curious to see if the frazil ice was forming on the Hudson River north of Warrensburg.  It was certainly cold enough to do so.

Before I reached the bridge that carries Rte. 28 across the Hudson at The Glen, I could see that the river was well jammed  up with this particular kind of chunky white ice that forms in areas of turbulent water.  As we head up north toward the Adirondack Mountains, the Hudson falls ever more steeply, with consequent turbulence.

Although it may look very much like snow, frazil ice doesn't fall from the sky, but forms when splashing water throws droplets up into the sub-freezing air, the droplets immediately turning to ice before falling back into the water.  These frozen droplets cling together, building up into slushy mats that eventually clog the river from shore to shore, as they are doing in this photo.  Eventually, the frazil clogs the river all the way down to the bottom, damming the flow and causing the frazil to rise up high on the banks, sometimes to heights as tall as 15 feet or more.

When I reached the bridge at The Glen, I could see that the river was still flowing freely here, with slushy mats of frazil rushing rapidly downstream.

I followed the river road downstream in my car, and had gone hardly more than half a mile before I could see that the frazil had stalled and was mounting up, pushing into the woods along the shore.

More than five miles further downstream, at the Thurman bridge, the river was still covered with frazil from shore to shore, although I could see where wide channels of open water had formed as the current pushed through.   But even these channels were covered with still ice today, after more than two days of temperatures well below zero.  This is the view looking upstream, and the view downstream looked much the same.

It's always an adventure to see what the ice on the Hudson will do.  Last year the frazil piled up to unprecedented  heights, engulfing the riverside road and shoving trees over in the forest.  It took several weeks for roadcrews to cut a lane through the heaps that covered the road.  Here's a photo I took last winter, on a patch of newly cleared road.

Let's hope the frazil is not quite so adventuresome this winter!


The Furry Gnome said...

It must be very interesting to have a river that size nearby to watch over the year. Nothing like that around here.

catharus said...

Must be fascinating to watch it form and move in the currents.

Ellen Rathbone said...

Beautiful! Hope you are feeling better. AND! Mark your calendar for June 5 or 9 - I'll be asking for your botany services at the Ice Meadows when I bring my eco-tour group there! Huzzah!

Jacqueline Donnelly said...

Thanks for your comments, Furry and catharus and Ellen. Yes, the Hudson offers wonders in every season, never static, always full of surprises.

Ellen, I am thrilled to learn of your pending visit. Can't wait to see you on our old stomping ground.