November 18, 2012

Winter is creeping closer and closer to Lake Wicwas.  The sun is rising lower, setting earlier, and the nights are getting cold.  Even the moon is trying hide from the coming chill.

The surface of the lake has cooled enough that the first skim of ice appeared in the marshes and along the edges of sheltered coves.  On Sunday it never completely melted during the day, but it is forecast to be warmer this week, so I doubt this is the start of ice on the lake.

Calm, cold nights always form interesting patterns as the water crystallizes.

It's an amazing aspect of physics that water changes from a completely fluid form of matter to a solid form when its energy (temperature) drops just a fraction of a degree below zero centigrade.  No getting thicker like honey or oil as it cools, but transforming to a new state instantly. 

Walking through a field on a cold morning I stopped to pick up a few bits of cotton or tissue paper someone had dropped on the ground.  But as I pinched them in my fingers, they disintegrated - they weren't paper at all, but ice crystals.  Rime ice had formed around some tiny dry stems sticking up out of the moss.

Rime Ice

I had never seen this around Lake Wicwas before.  It isn't water that condenses first and then freezes, but rather super cooled droplets in the air that are below 0C, which upon encountering a surface that is also below freezing, crystallizes instantly.  This process captures air pockets in the ice which is why it is white, porous, and brittle.

Why it formed on just a few lone stalks is a mystery to me.  Why didn't it form on the pine needles?  Why didn't it form on all the stalks?  Perhaps it's the combination of moisture captured in the moss and the thermal conduction of the stems. 

The water isn't too cold for the birds though.  Our loon chick is still on the lake, as observed by one of our bird watchers (thank you!).  There are still a few wood ducks around as well, but only in groups of two or three - no large flocks.  We also saw several mallards, including a group of five that was just floating around, sometimes not even making a ripple.  Perhaps they are gathering energy for the next leg of their journey.

Mallards

Even the rawness of November breaks now and then, bringing a tranquil moment to the lake.