Wednesday, January 23, 2013

Cold Weather Friends

 Cold today?  Well, yes, kind of.  It was 12 below when I peered out my frosty windows this morning at a sky so clear you could see all the way to heaven.  Most people hate the weather this cold.  Lucky for me, I have some friends who love it as much as I do.  And even luckier,  we were able to get together today to watch the amazing transformation of the Hudson River as it filled with frazil ice.

Here's my friend Sue on the road that follows the Hudson north of Warrensburg, gazing at the vast expanse of snowy-white jumbled frazil that has packed the river from shore to shore and caused the river to rise well over its normal banks. We were on our way still further north to The Glen, where we would meet Evelyn Greene, who probably knows more about frazil ice and how it forms than any other person in New York State.

At The Glen, a bridge passes over the Hudson, and here we could stand and watch as loose mats of frothy frazil floated swiftly downstream.  From the other side of the bridge we could look upstream to patches of whitewater, where some of the frazil was no doubt forming as we watched.  This particular kind of ice requires both turbulent water that throws droplets into the air and a very cold temperature that freezes those droplets before they fall back into the river, where the droplets adhere to each other to form the slushy mats we see in this photo.  Conditions were certainly right for frazil formation today.

While the formation of this ice is interesting enough in its own right, what really interests those of us who are plant enthusiasts is how this frazil creates a habitat uniquely suited to many rare native plants, the kind of plants that thrive in a section of Hudson riverbank that is known as the Ice Meadows.  This section of the river is downstream from the bridge at The Glen, and that's where we proceeded next.

Here's Evelyn leading Sue and another friend named Mary down to the Ice Meadows shore.  At this point, the frazil had stalled and filled the river completely from shore to shore.  Over the course of the winter, continued formation of frazil can result in massive deposits of ice up to 15 feet thick along these banks, creating a habitat favorable only to plants that have evolved to tolerate such harsh conditions. (To see some of these plants, type "Ice Meadows" into this blog's search bar and visit my posts that featured them.)

Curious to see at what point the flowing ice had stalled and filled the river, we hiked back upstream for some distance until we located the juncture.  Even as we watched, we could see and hear the fast-moving frazil mats slow to a halt as they jammed against the buildup.  The relentless current, however, caused masses of ice to form wedges that shoved and plowed through the jam, only to stall again at another spot.  The whole dynamic process was fascinating to observe, and we might have stayed for much longer to watch it if we hadn't nearly frozen in place.  The afternoon temperatures barely reached the teens, and a brisk wind kept shoving that frigid air into any gap it could find in our cold-weather garments.  When stamping our feet no longer brought feeling back into our toes, it was time to head home.

Before we parted, we told Evelyn we would follow the river along the west bank and report back to her how far the solid frazil pack extended.  A few miles further south, the pack was still solidly filling the river, and the heaps of frazil were a truly impressive size.

It was not until we reached the bridge between Warrensburg and Thurman that we saw any open water.  It is at this point that the Schroon River joins the Hudson, and it appeared that the Schroon had come rushing in with great force to sweep all the ice away.   The Hudson continued open below the bridge and as far downstream as we could see.

Can you see the moon in the photo above, that pale translucent dot in the upper right corner?  That lovely moon riding that clear blue sky just seemed like the cherry on top of this beautiful day with delightful friends along this amazing river.


Andrew Lane Gibson said...

Hard to believe those are the same shorelines I stood on a number of months ago with so many fascinating plants in full bloom. I can see how that ice really does an amazing job of keeping that habitat open and readily available to only the most able of plants!

Raining Iguanas said...

I've been so busy I haven't been here to visit. I missed a ton of great photos. I will sip my coffee slow and catch up. Great job as always.

suep said...

great as always to be outside with you all, getting our dose of superfresh air -
hey I think I can finally feel my TOES again

Jaime said...

Winter Wonderland!

catharus said...

Is any more known about what enables certain species to survive this frazil ice? That is, what is it about those species that manage to live at places like Ice Meadows?

Jacqueline Donnelly said...

Thanks, dear friends, for stopping by to leave your always welcome comments.

Regarding the question catharus asks, I think the most important influence the frazil has is to keep the trees from growing tall and shading the shore, thus preserving the open grassland habitat. This process -- plus the fact that the massive ice pack doesn't melt until rather late in spring -- also discourages the growth of many introduced species that would normally invade such an open area, which is also rather nutrient poor, due to frequent flooding. The hardy native grassland and wetland species that have evolved to thrive in this environment would probably thrive in many other places,too, if those other places had not been overrun with alien invasives. Or shaded out by the growth of woody plants. There are many woody shrubs that grow on the Ice Meadows, but all are dwarfed by the frazil-influenced environment. Dogwoods and Shadblows and Alders that would normally tower over our heads barely reach our knees out on these shores.