The Cellar Image of the Day

We've seen tons and tons of different snowflakes under an ordinary microscope, but what happens if you look closer?

This page has four shots of even closer images of a single flake. In fact, it's part of a single arm from a single six-sided flake.

Another page has put all the magnifications together so you can sort of imagine yourself getting closer and closer to the flake, until it's sort of incomprehensible how close you actually are.

Is it best to consider such things in the midst of summer?

It looks like a concrete snowflake.

How do they know that no two snowflakes are alike? They can't really check, can they?

Awesome! I do prefer snowflakes at a normal size or through an amplifying glass or loupe, however.

Now there's a worthwhile job -platinum-plating snowflakes....

(shouldn't take the piss -the other half is an SEM chap and gold-plates all sorts of weird stuff

)

But the fact is if you look long enough, you will find identical "looking" snow flakes.

Quote:

Wilson A. Bentley, a farmer who was born, lived and died in the small town of Jericho in Vermont was called “The Snowflake Man”. He supported this “all snowflakes are different” theory. Around 1884, at the age of 19, he became the first person to photograph a single ice crystal, by cleverly marrying a microscope to a camera, using an adjustable bellows mechanism. In 1920, the American Meteorological Society elected him to the state of Fellow. They also awarded him their very first research grant, in recognition of his “40 years of extremely patient work” - for which they gave him $25. He continued working in this field until his death in 1931, by which time he had taken 5,381 “photomicrographs” of individual snowflakes. Towards the end of his life, he said that he had “never seen two snowflakes alike”. And so the story arose that all snowflakes are different.

But in 1988, the scientist Nancy Knight (at the National Center for Atmospheric Research in Boulder, Colorado) was studying wispy high altitude cirrus clouds. Her research plane was collecting snowflakes on a chilled glass slide that was coated with a sticky oil. She found two identical (under a microscope, at least) snowflakes in a Wisconsin snowstorm.

They were hollow hexagonal prisms, rather than the classical six-spoked star-shapes – but as far as snowologists are concerned, they counted as snowflakes. But if you want to be pedantic, they probably weren't identical if you were to look at the actual molecules – but at this level, is anything identical?

Since the earth was formed about 4.5 billion years ago, about a million million million million million snowflakes have fallen – but Mr. Bentley made his pronouncement of the cold hard facts after looking at just over 5,000 of them.

Thank you for the snowflake- it is about 105 degrees here in the California desert, so even the thought of snow is comforting

How do all six arms of the snowflake know to grow into the same shape? That's what I want to know.

I usually try and do this at least once each winter, personally I'm going for catching a falling flake, and imaging it without any prep. All that freezing with liquid nitrogen and bombarding with ions might change the structure.
Then again I haven't been successful yet.

Quote:

Originally Posted by Beest

... Modern (for at least the last ten years) electron microscopes can image non conducting objects by using a low gas pressure in the chamber, incoming beam ionizes the gas around the beam providing a conducting path to dispel charge.

Low beam currents, and accelerating voltages, also help reduce sample charging in the Field emission type SEMs.

I bet you're sorry you asked now