How Beautiful Snowflakes Are Formed

Snowflake in a microscope / AlexeyKljatov Wikimedia CC BY-SA 4.0

 

Snowflakes can be big and heavy and they can be light and feathery. No two snowflakes look alike, but they all form the same way. Starting out as a tiny particle of dust in the atmosphere and turning into a beautiful snowflake. Find out how a dust particle turns into a pretty snowflake?

How Snowflakes Form

Precipitation comes in many forms such as clouds, fog, rain, sleet, hail and snow. A snowflake starts out as a dust particle. Then water vapor starts to condense onto the dust particle and if the temperature is cold enough it freezes.

Most naturally occurring ice is shaped in a hexagonal structure. The snowflake becomes more formed because water molecules have an attraction for each other and water is more stable in the form of ice.

The water molecule is even more stable in the form of ice when arranged in hexagonal layers, and that gives the snowflake a 6-sided symmetry. As more and more water vapor condenses onto this ice crystal, the snowflake grows.

Several factors influence the shape a snowflake, the temperature, humidity and the air currents. If there are a lot of dust and dirt particles mixed in during this freezing process, the shape of the snowflake is affected.

As these ice crystals move up and down in the cloud with the updrafts and downdrafts they continue to form and be shaped. Finally the snowflake is heavy enough to escape the clouds updrafts and falls to the ground.

Falling to the ground can also alter its shape. If the snowflake spins it will probably keep its symmetrical shape. If they aren’t spinning when they hit the ground they will lose their shape and be lumpy.

Snowflakes on wood / Wikimedia CC BY 2.0

Common Snowflake Shapes

The shape of the ice crystals that form the snowflake is dependent on temperature. Here is a list of their shapes and the temperature that they formed in.

• 25 Fahrenheit – 32 F (-4 C to 0 C): Thin 6-sided hexagonal crystals, formed in the high clouds
• 21 F – 25 F (-6 C to - 4 C): Needles or flat-sided crystals are formed in the middle height clouds
• 14 F – 21 F (-10 C to -6 C) : Hollow columns
• 10 F – 14 F (-12 C to -10 C): Sector plates, which are hexagons with indentations
• 3 F – 10 F (-16 C to -12 C): Dendrites, lacy hexagonal shapes.

Snowflakes are composed of many ice crystals that affect their shapes. They might start out as a one shape and land as another shape. 

You will probably never see two snowflakes that look alike, it is a constant though that in the formation of one, it is always 6-sided, or hexagonal.

By Jason Hollinger CC BY 2.0 via Wikimedia Commons

Why is Snow White?

Water is clear, so why is snow white. The answer has to do with the fact that snowflakes have so many light-reflecting surfaces that they scatter the light into all of its colors, so snow appears white. 

It has to do with how the brain perceives the light into the color.

Sometimes snow can also appear to be blue. When you shovel deep snow, you might notice the snow is blue in the deep snow. 

This happens when light does penetrate the snow deeper. The red and yellow colors are easily dispersed leaving the blue color.   

Graupel

There is another form of snow that some people have never heard of or seen and it is called graupel, also referred to as snow pellets. 

Some describe it as soft fuzzy hail. It starts out as a snowflake and then combine with supercooled water droplets that are frozen together. These are small soft pellets, not large or hard ice like hail is. 

 

Updrafts and Downdrafts in a Cloud

 

A snowflake can go up and down in a cloud gathering more crystals that form its shape until it gets heavy enough to fall to the ground. You can actually see this updraft and downdraft action yourself when it hails.

The next time it hails and if the hail is big enough, look for ones that have broken in half on the ground. You can see rings inside the hailstone. 

Each ring represents a trip up and down in the cloud. The hailstone will then rise up again and gather another layer of ice, then it falls in the downdraft and melts a little bit, rises up again and refreezes picking up another layer of ice until it gets heavy enough to fall to earth.

The clouds that make hail are cumulonimbus clouds or the towering thunderheads you see. The updrafts in these clouds are much stronger than in clouds that produce snow.

Copyright © Sam Montana 2009-2014