Snowflakes: Not Just Frozen Rain

snowflakes

By Valinda Huckabay

You may already know that each snowflake is unique — there are never two created exactly alike. But did you know that snowflakes grow?

How Snowflakes are Formed

Snowflakes are made of ice, but they are not just frozen water. Sometimes raindrops freeze as they fall, but this is called sleet, not snow, and it doesn't have any of the elaborate and symmetrical patterning found in snowflakes.

Snowflakes have fascinated scientists for centuries. Johannes Kepler, a 17th-century astronomer and mathematician, discovered that all snowflakes are unique variations on a six-sided crystal. Snow crystals form when water vapor within a cloud shrinks directly into ice. Intricate patterns emerge as the ice crystals grow. A snowflake typically begins as a single ice crystal, then becomes more complex by growing branches, combining with other ice crystals, and even gathering tiny frozen water droplets on its surface from within the cloud.

Common Shapes

In 1951, the International Commission on Snow and Ice produced a fairly simple and widely used classification system for solid precipitation (stuff that’s not rain but falls from clouds), which defined the seven basic snow crystal types as plates, stellar crystals, columns, needles, spatial dendrites, capped columns and irregular forms — the most common snow crystals.

Caltech physicist Kenneth Libbrecht, however, prefers to use his classification system of 35 types of snow crystals. Libbrecht studies the physics of crystal growth; basically how temperature and electrical charges interact to produce snow crystals. He uses a high-quality, low-power photo-microscope that he designed himself to study snow crystals up close. He is one of the world's top snowflake experts, and has written seven books on the subject.

Libbrecht received the esteemed Lennart Nilsson Award this year for his work with what he calls "nature's frozen art." The Nilsson Prize is awarded by the Karolinska Institute, and is considered the Nobel Prize of scientific photography.

Artificial Snow?

So what about the snowflakes in artificial snow? Because artificial snow machines shoot out a mixture of water and compressed air, the water comes out as fine droplets, the air cools them and the droplets freeze. Artificial snow is, therefore, made up entirely of merely frozen water droplets, with none of the elaborate structure found in snowflakes.

So nothing beats the real deal ... as one of the most amazing and beautiful feats of nature, watching snowflakes fall is always fascinating entertainment!

Classroom Discussion

  • What was the most amazing snowflake you’ve ever seen?
  • What do you think makes snowflakes stick together so you can make things like snowballs?