Archived Story

Let it snow, let it snow, let it snow!

Published 7:19pm Wednesday, December 29, 2010

The fallen snow has captured the unmistakable footprints of a bird. Photo by Terri Gordon


Off the Water

Winter is not winter in southwest Michigan without snow. Many people dislike snow. It’s messy to drive in, difficult to walk through and it’s cold.

While modern society considers it a nuisance and works to remove it from roads, parking lots and walkways, early people and people living in northern latitudes adapted to living in it and learned to use it to their benefit. They invented snowshoes and skis to help them get around in it. They named the various types of snow they encountered and understood their natures and their purposes.

Chuck Nelson, Sarett Nature Center’s chief naturalist and executive director, calls snow an “interesting phenomenon.” It forms when air masses meet. When warm air comes up from the gulf stream, instead of mixing with the cold air mass already in place, it rides up over it.

As warm air rises over colder air, it cools too.

“Cooler air can hold less moisture than warm air, so sooner or later, it has to crystallize, or become liquid form,” Nelson explained.

The first snow flakes, or crystals, form very high in the sky. They are columnar — six-sided —and hollow. These crystals form in front of an incoming snow system and appear to the human eye as haze, or wispy cirrus clouds.

As moisture increases, crystals start forming lower and lower in the stratosphere, and they encounter particles of dust and salt and even dead bacteria. These particles give the crystals something to form around, a “condensation nuclei.”

“From this point on,” Nelson said, “all the snowflakes will form around that condensation nuclei.  Now you get a hexagonal plate. It’s got enough time as it falls to fill in all the spaces, so it’s a solid plate. As it crystallizes faster, it gets moister yet. And now it’s snowing pretty hard and it doesn’t have time to fill in all the way, so you get a six-sided flake.” The bulk of a snowstorm is made up of these six-sided flakes called “stellar crystals.”

Different conditions create different kinds of flakes. There are roughly a dozen common types.

“The rarest and prettiest of all snow flakes is when the column crystal falls and gets swept up to where they’re making plates and then the column acts as a condensation nuclei and a plate crystal forms around it, making the rare and beautiful tsuzumi crystal,” Nelson said. The flake is named after a Japanese drum of the same shape.

To get a closer look at snowflakes, Nelson recommends placing a dark cloth over a bush to collect them, and then viewing them through a magnifying glass. Too warm a cloth will melt flakes, so folks want to cool it first.

Near large bodies of water, like Lake Michigan, a second phenomenon takes place. Once a storm has passed, cold air comes “swishing around” behind it. Cold air being heavier than warm air, it pushes the warm air up. As it travels over the lake, “which is like throwing buckets of water into the air,” said Nelson, it takes up the moisture and creates lake effect snow. Lake effect snow helps keep the ground warmer and is part of why southwest Michigan can grow the fruit it does.

Not only are there different kinds of snowflakes, there are different types of snow as it lies on the ground.

Dr. William Pruitt, a zoologist from the University of Manitoba, in Winnipeg, Canada, was the first to document the kinds of snow, using words from the languages of the Eskimos (Inuit), Native Americans and Lapps.

The entire body of snow that blankets the ground is called “api”  snow. “Qali” snow is the snow that falls on the trees.  Qali snow helps animals, like rabbits, survive because it bends branches over, creating sheltered areas and bringing food sources, like the tender treetops, closer to the ground where they can be reached.

As the earth radiates heat up under the snow, it melts the bottom layer slightly, creating spaces where small animals like mice and voles can live protected from the harsh cold and other elements, and where they can find food that is not completely frozen. This layer of snow is called “pukak” snow.

One of Nelson’s favorite activities is heading out, on skis, or in snowshoes, in search of animal tracks.

“You can go out and learn more about animal behavior, and can find out what’s going on with groups of animals, or individual animals. There’s nothing finer,” he said.

If people know what they’re looking for, they can see where foxes have stopped to listen for mice living in the pukak snow, even where they have pounced to catch them. Rabbits, coyotes, birds, humans too — each animal has its pattern, and leaves them, unmistakably, in winter’s snow.

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