Thursday, February 4, 2021

Four paradoxes of snow

Four paradoxes of snow . . . musings arising from this week's weather.  

Light and Heavy.
Snowflakes are so tiny.  So tiny and and so light.  But when they fall like they did earlier this week, they make so much, heavy work.  It's a bit of what I teach my students in calculus class: there are these tiny things we study that are so small that we call them "infinitesimals" (epsilon, dx, dy), but when you add them all up, they make ups something really big.

Dark and Light.
The storms that bring in the snow roll in on huge clouds that block the sun, and at night they block the stars and moon, and yet the nighttimes are brighter than ever because of all the reflected light off the snow.  I often wake up in the middle of the night after a snowfall, thinking it must be morning already, because the nights just luminesce with the snow on the ground.

Cold and warm.
Snow comes in because of cold weather storms, but it traps air to become one of the best insulators around.  I grew up loving to see the snow on my roof: it meant the attic insulation was working (so heat from the house wasn't melting the snow away), and the house underneath was staying cozier than ever.  And snow piles, with their amazing insulating abilities, can last months into warmer weather.  

Rigid and Free.
Snowflake Bentley was the most prolific early photographer of snow, and his fascinating pictures have always made me marvel.   It's amazing to me that a snowflake, starting with a grain of who-knows-what, picking up random water molecules as it falls through the air, remains so incredibly six-fold symmetric.  How do the water molecules on the north side of the flake know to match the ones on the south side?  There's so much variation from the center outward, that it makes the symmetry along the edges that much more stunning.

And yet, if you remove the freedom of falling through the air, and if you force snow to form under constraints (like frost on a windowpane), then you get structures that look almost alive: like ferns, or feathers, of things that can blow and move.  Snow that falls freely forms rigid shapes; snow that forms under conformity seems to finally have a will of its own.  


It makes me feel like there ought to be a metaphor in here somewhere, but I can't pull it together quite.  Mostly, I just love how snow up-ends the world (and my thinking) for a little while, until it melts away again.  

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