Wrapped in layers of knit and fleece, cheeks flushed from the biting wind, a skier plunges down a powdery mountain. A fresh coat of snow transforms the neighbourhood hill into the optimal, gravity-embracing voyage for adventurous sledders. Meanwhile, a freak snowstorm paralyzes a city, leaving drivers disgruntled and pedestrians with soggy socks as they make their way along slushy sidewalks. In another setting, perfect snowballs form in the hands of playful children. None of these quintessentially Canadian winter scenes could happen without snow—the lovely, powdery stuff that we know all too well. And at the centre of each snowfall is the snowflake—a fascinating and beautiful symbol of winter.
How are snowflakes made?
A snowflake forms when a water droplet freezes around a speck of dust floating inside a cloud. The frozen droplet then forms a crystal with six sides. As the droplet falls to the ground, water vapour freezes and clings to it, causing the crystal to grow and develop branches, or “arms,” which sprout from the crystal’s six sides. Since the temperature and humidity are consistent around the tiny crystal, the six arms all grow at the same speed and with perfect symmetry.
Does temperature play a role?
Many factors affect the shape and size of snowflakes, including temperature, humidity, and air currents. There are four types of snowflakes—columns, needles, dendrites, and rimed—and each tends to form in a different temperature range. Dendrites, which are the classic, doily-shaped flakes we commonly think of, tend to form at around -12° Celsius.
Generally, colder temperatures produce snowflakes with sharper, more intricate arms, while warmer temperatures, which cause snowflakes to form more slowly, produce smoother, simpler shapes.
Are snowflakes really unique?
It’s true—no two snowflakes are identical. Since each snowflake follows a unique route from the sky to the ground, each encounters slightly different environmental conditions. The result of these subtle differences in their path is that there will never be duplicate snowflakes.
Why is snow white?
If snow is made up of clear ice crystals, why does it appear white? For the answer to this mystery, we have to understand the properties of light. Visible light from the sun is made up of different frequencies. When light hits an object, these frequencies are absorbed and reflected back to our eyes, which interpret them as various colours. When light hits snow, it reflects off of the many surfaces of the crystals, causing the light to scatter. The light frequencies bounce in multiple directions, reflecting all of the visible frequencies of light back at your eyes. Because the “colour” of all combined light frequencies is white, this is how snow appears to us. It’s similar to the way that glass looks clear, but when it’s crushed in a mound, it appears white.
What kind of snow makes the best snowball?
The snowball is the ultimate weapon of winter. There’s so much satisfaction in packing and throwing a perfectly packed sphere of snow. The ideal snowball should be made using slightly wet snow, which adheres better and results in a more tightly packed ball. The perfect temperature for snowballs is around 0°, because the snow will be wetter near its melting point. If the snow is powdery and dry, ditch the snowy battlefield and hit the slopes. Lighter snow is better for skiing and snowboarding.
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