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Thursday, January 3, 2008

Feeling Frisky


Aurique had great fun in the fresh fallen snow. The flakes were dropping lightly all around him and he and Splash jumped and played into as if they were puppies and this was their first snow fall. Aurique is so photogenic whereas poor splash will never truly take a good picture. Being black on a white background doesn't do so well for the pictures.

The flakes were amazingly large. They were the very detailed type of snowflakes that make you wonder if it really is true that no two flakes are the same.

Of course wondering got me to thinking about snow flakes, so I did a little research on the matter. Did you know that it is always snowing some place? Snowflakes always have six points..., like the Star of David. I never knew that!!!!
It is amazing what you will find on the internet these days.

Symmetry of Snowflakes
Source - Snowflakes and Snow Crystals

Snow crystals form some elaborate and complex shapes, often displaying lacy, branching structures. They are nothing more than ice which has condensed from water vapor, but..., the simple act of water vapor freezing into ice does produce such intricate designs.

Water molecules have to diffuse through the air to reach the crystal, and this diffusion slows their growth. The farther water molecules have to diffuse through the air, the longer it takes them to reach the growing crystal.

Consider a flat ice surface that is growing in the air. If a small bump happens to appear on the surface, then the bump sticks out a bit farther than the rest of the crystal. This means water molecules from afar can reach the bump a bit quicker than they can reach the rest of the crystal, because they don't have to diffuse quite as far.

With more water molecules reaching the bump, the bump grows faster. In a short time, the bump sticks out even farther than it did before, and so it grows even faster. This a branching instability, small bumps develop into large branches, and bumps on the branches become sidebranches. It continues to become more complex. This instability is a major player in producing the complex shapes of snow crystals.And since the ambient atmospheric conditions are nearly identical across the crystal, all six budding arms grow at roughly the same rate.

The temperature seen by the snow crystal is not constant in time, however, since the crystal is being blown about and is thus carried over great distances in a cloud. But the crystal growth rates depend strongly on temperature. Thus the six arms of the snow crystals each change their growth with time, reflecting the ever-changing conditions in the cloud. And because each arm sees the same conditions, each arms grows the same way. When the branching instability applies itself over and over again to a growing snow crystal, the result is called an ice dendrite. The word dendrite means "tree-like," and stellar dendrite snow crystals are common.

If snow crystals are grown in a laboratory, in air below atmospheric pressure, they have fewer branches. This is because diffusion doesn't limit the growth so much at lower air pressures, so the branching instability is not so strong. At higher pressures, more branches appear. The growth of snow crystals depends on a balance between faceting and branching. Faceting tends to make simple flat surfaces, while branching tends to make more complex structures. The interplay between faceting and branching is a delicate one, depending strongly on things like temperature and humidity. This means snow crystals can grow in many different ways, resulting in the great diversity we see in snow crystal forms.

The intricate shape of a single arm is determined by the ever-changing conditions experienced by the crystal as it falls. Because each arm experiences the same conditions, however, the arms tend to look alike. The end result is a large-scale, complex, six-fold symmetric snow crystal. And since snow crystals all follow slightly different paths through the clouds, individual crystals all tend to all look different.

The Snowflake Man

"Under the microscope, I found that snowflakes were miracles of beauty; and it seemed a shame that this beauty should not be seen and appreciated by others. Every crystal was a masterpiece of design and no one design was ever repeated., When a snowflake melted, that design was forever lost. Just that much beauty was gone, without leaving any record behind."

Link to snowflakesWilson "Snowflake" Bentley 1925

From the earliest memories of our childhood, many of us can remember hearing the phrase "no two snowflakes are alike". This discovery was made in the small rural town of Jericho, Vermont by Wilson A. Bentley (1865-1931).

A self educated farmer, Bentley attracted world attention with his pioneering work in the area of photomicrography, most notably his extensive work with snow crystals (commonly known as snowflakes). By adapting a microscope to a bellows camera, and years of trial and error, he became the first person to photograph a single snow crystal in 1885.

Snowflake collageHe would go on to capture more than 5000 snowflakes during his lifetime, not finding any two alike. His snow crystal photomicrographs were acquired by colleges and universities throughout the world and he published many articles for magazines and journals including, Scientific American and National Geographic.

In 1931 his book "Snow Crystals", containing more than 2400 snow crystal images, was published by McGraw-Hill but has long been out of print. A soft cover copy, identical in all respects, can be obtained today from Dover Publications, Inc.. On December 23, 1931, Bentley died at the family farmhouse in Jericho. Because of his wonderful work with snow crystals, he became affectionately known as "Snowflake" Bentley.

2 comments:

keith hillman said...

Firstly what a wonderful photo of Aurique!What does the name mean?
As for snowflakes, it's incredible that something seemingly so simple can be so complex! Very informative!

jadey said...

Well there what some interesting snowflake information you have here. What a wonderful nickname to be called snowflake Bentley very nice. I love the pic of Aurique!