Life cycle of a snowflake

The crunch of fresh snow underfoot, the peaceful quietude: Most people long for a white Christmas. But the snowy landscape is beautiful not just from afar, but also very close up.

Snow is nothing more than water in solid form, which happens when a water droplet attaches to a particle of dust or soot and freezes in the cold upper atmosphere. The temperatures must be between minus 4 to minus 20 degrees Celsius (24.8 to -4 degrees Fahrenheit) for this to happen.

A snowflake starts on a flat, hexagonal base that is a mere 0.1 millimeter in diameter. The shape emerges due to the intermolecular force of hydrogen bonding in H2O.

As ever more water freezes onto the hexagonal crystals, the snowflakes begin to grow extensions called dendrites. This gives snowflakes their typical star-like shape - in infinite possibilities, depending on temperature, wind conditions and humidity in the clouds where they form.

It takes about an hour for a snowflake to make its way from a cloud to the surface of the Earth. Temperatures of greater than minus 5 degrees Celsius and more humidity cause larger flakes. At lower temperatures and in drier conditions - like at the poles - needle ice and plate crystals make up the snow.

The moister, larger flakes are good for things like building snowmen. Smaller, colder snowflakes bring drier powder snow.

Glaciers form as snow builds up and compacts over time. Snow that's melted and refrozen becomes a kind of granular ice called "firn." The word, in fact, comes from German and means "of last year." Blue- or green-tinted, shimmering glaciers have become important indicators of climate change.

The white "color" of snow is in fact an optical illusion: snow is made up of water, which is colorless. But snow crystals act like mirrors, reflect all different light frequencies simultaneously, which results in the appearance of a white hue to our eyes.

Regardless of their origin, snowflakes will continue to inspire us with their beauty and individuality - and ultimately, their transience, as they melt back into water.