The Science of Snowflakes


   About this time of year a lot of folks start thinking about snow. Most people will admit that the first lazy floating snowflakes of winter are a pretty sight. It's only after we've had a half dozen snowstorms that we start looking at snow with less than kind thoughts. But there was once a man who loved all snow, no matter how much fell! He not only loved it, he studied it.

   Snowflakes are actually pretty neat. They are much more than just frozen rain as many people think. Instead they are made up of as many of 180 billion molecules of water. To form, water droplets in clouds must reach less than 32 degrees F (0 degrees C.) When the water freezes, it creates snowflakes out of crystals.

   Just as with raindrops, a snowflake begins as a droplet of water which condenses on a speck of dust. The droplet freezes and more droplets condense and freeze on it (remember how ice will stick to your tongue?) If the cloud temperature stays below freezing, enough droplets will freeze and collect to form a snowflake. Because of the way water molecules fit together, most snowflakes are six-sided (hexagonal.) When the snowflake gets heavy enough, it descends to Earth.

   In the 1800's we knew a little about snowflakes but it was not until Snowflake Bentley turned up that a serious study of the white stuff occurred. There lived in 1880 a curious man named Wilson A. Bentley who decided he had to know more about snowflakes. He resided in a great place for such studies, Vermont! Bentley purchased a microscope and went outside when it snowed to view a close-up of a snowflake. It was a breathtaking view of a delicate incredibly beautiful six-sided ice sculpture. Wilson was hooked! He then purchased a camera to take a picture of the snowflake so that he would have a permanent record of what he had seen.

   Bentley studied snowflakes for the next forty years and was dubbed Snowflake Bentley. He took over 5000 photographs of snowflakes and developed a system for categorizing over 80 different types of flakes. He was amazed to find that there were snowflakes shaped like needles, hollow columns, capped columns and more.

   Meteorologists later perfected Bentley's system for organizing the types of snowflakes. They also discovered that it was the conditions and location within the cloud which determined the type of flake that would form. In the highest clouds where temperatures are lowest, snowflakes take the shape of six-sided columns sometimes with the ends capped. Slightly warmed temperatures in the middle cloud layers will produce both a column shaped flake and a flat six-sided shape called a hexagonal plate. The lowest clouds, and warmest temperatures create snowflakes in hexagonal plates, short columns, long thin needles and stars. These snowflakes which form in warmer temperatures are also the largest flakes.

   There is an age-old saying that no two snowflakes are alike, but is it true? Well although Bentley never discovered two snowflakes exactly alike, there is no scientific reason why more than one flake cannot have exactly the same shape. It's just that considering that a snowflake is composed of over 180 billion molecules, odds do not favor 2 snowflakes having exactly the same shape.

   So how big do snowflakes get? The average snowflake measures around a half an inch. You do need a magnifying glass to see the shape. Some snowflakes, and you've doubtlessly noticed them lazily floating to the ground, are rather large. Some of the largest snowflakes range from three to four inches in length!

   Another snowy question frequently asked is how much rain is equivalent to an inch of snow? That does depend on just what type of snow we are referring to. I'm sure you've noticed that some snows are lighter and fluffier than others. In general, one inch of water is the equivalent of six inches of heavy wet snow, or twelve inches of very light puffy snow.

   If you feel the Snowflake Bentley is someone worth copying, you too can study snowflakes. All you need is a piece of black felt on a piece of cardboard or plexiglass. You could use some other piece of material, but felt works best. The only other tool you need is a magnifying glass. Snowflake gazing works best if you place to felt covered cardboard in the freezer for a half hour or so before going outside. This will prevent the snowflakes from melting too quickly. Allow a few flakes to fall on the felt and then you can study them with the magnifying glass. And who know, perhaps you will be the first to find two snowflakes exactly alike!


Copyright © 2001 Kathy A. Miles and Charles F. Peters II