Frost on cabbage. Discover the wonder of winter frost, ice and snow.
PHOTO: DAVID CAVAGNARO
Winter frost, ice and snow puts on a miraculous show in cold winter months.
Once or twice each winter, a miracle happened on the sloping, snow-covered wheat fields of my grandfather's western-New York farm. A rare warm day would send meltwater spilling into a wide, bowl-shaped swale of some 20 acres. That night, as the water nearest the soil seeped slowly into the earth, frigid air would quick-freeze the upper few inches. By morning the entire field was glazed with a vast, glistening pane of ice: flat, smooth and more than thick enough to hold an ear-muffed, scarf-wrapped boy atop a pair of hockey skates.
Like skating on air, that's the only way I can describe gliding across acres of open field on a transparent surface suspended several inches above ground. The field itself — stones and soil and wheat stubble and all — was clearly visible through the frozen window and air space below. And so I would spend my days, just me, the field, and the whir and click of skates, until a heavy snow or another sudden thaw undid the miracle.
In most parts of the country, such is the stuff of winter. Winter snow, ice and frost alter our lives in all sorts of ways, good and not-so-good, pleasurable and irksome. At the core of all this is neither snow, ice nor frost, but the true miracle, one of the most remarkable substances known to humankind: water.
In the presence of cold, water performs amazing feats. On its own, water cannot freeze. But given an anchor from which to build - a speck of dust, a snow crystal, a stone or a bit of leaf - water molecule near freezing will cluster, stretch out, break apart and gather again, like motivated, molecular square dancers, eventually forming structured groups. Needle-shaped crystals, spread outward on the surface of a pond or lake, forming a delicate, spiny skin which moves first from the edges toward the center, then thickens. Given a really cold, still day, you can hear ice hiss and crackle as it grows.
In the air, water crystals tumbling earthward transform themselves with each twist and turn, each tiny gust or temperature change. A six-sided star may suddenly grow lance-like arms; a hollow column may sprout a fringe of needles at one end, then break apart, seeding the sky with bits of ice from which more crystals will grow.
Most chemical compounds crystallize into predictable shapes, but not so with water. Scientists have identified no less than 80 types of ice crystals: bullets, cones and six-sided prisms, feathery flowers and upended tables, chimney-like columns and inverted funnels, winged plates, even rare three- and five-sided crystals. And that's just the beginning of water's myriad cold-weather forms. There is fern frost: the delicate, lacy fingers of ice that grow from unseen scratches and bits of dust on windowpanes. Mountain-top trees shrouded in cold clouds become coated with milk-colored rime ice. At the bottom of every avalanche is depth hoar, snow recrystallized into a lovely, but perilously weak, honeycomb structure. There are miles-wide floating bergs; slow-flowing, earth-sculpting glaciers; balls of hail as big as your fist; tiny white pellets called graupel.
Fantastic Floating Frozen Water
Perhaps most remarkable of all water's properties is its ability to float on itself. Picture an ice cube floating in a glass of water. Big deal, you say? Big deal indeed. Were it not so, life as we know it would be entirely different — or might never have occurred at all.
Virtually every other substance in nature contracts, or shrinks, and becomes denser as it gets colder. When it warms, it expands and grows less dense.We all know why a room is warmest near the ceiling and coldest near the floor: Warm air rises above cold air.
Liquids, too, obey this law. All liquids, that is, except water. At first, water sticks to the rules and, just like everything else, becomes denser as it cools. But at the moment its temperature drops from 39.2 degrees to 39.1 degrees, the upstart liquid does something entirely contrary to the laws of science: It begins to expand and become less dense — until, at 32 degrees, it becomes ice and floats on the denser water.
Lucky thing for us. If water behaved as other liquids do, the coldest water would be the densest and would sink to the bottom. Instead of freezing from the top down, ponds and lakes would freeze solid from the bottom up. Fish and all other aquatic life would die. Land animals would perish, too, from lack of water. Even the ocean depths would gradually fill with ice. Ultimately, say scientists, the entire planet would freeze.
But no: Ice floats. What's more, it acts as an insulating blanket. Ponds and lakes are shielded from frigid air temperatures. Because water at the bottom never is colder than 39.2 degrees, fish and other aquatic life can survive until spring. Meanwhile on land, as many as 18 million ice crystals in each cubic foot of snow trap the Earth's warmth like a down quilt. Deer mice, voles, red squirrels, shrews, spring peepers, insect larvae and countless perennial plants spend the winter safe beneath snow's protective cover.
Winter Frost, Ice and Snow: It's the Water
The images of winter are full of glisten and sparkle; of landscapes white and homes icicle-fringed; of slip and slide, icy crunch and frosty crackle. It seems only fitting though, as we savor nature's winter wonderland, to acknowledge the greatest wonder of all. In each drop of water there is life and beauty for every season: spring's renewal, summer's lush growth, fall's frosts, winter's crystalline coat.