August 29, 2007: Snowflake under electron microscope

[Undertoad]

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?

[Sheldonrs]

Sort of loses it's charm this way.

[SteveDallas]

I disagree... it's fascinating.

[Flint]

Fight! Fight! Fight!

[Trilby]

It looks like a concrete snowflake.

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

[Scriveyn]

Originally Posted by Brianna

It looks like a concrete snowflake. ...

I had been wondering how they did it, beacause electron microscopes can only image objects whose surface is electrically conductive. - So these are platinum coated snowflakes.
Can we make a necklace of them after they're no longer needed for science? :p

(see their explanation here: http://emu.arsusda.gov/snowsite/4100/4100.html)

[smurfalicious]

You are not a beautiful and/or unique snowflake.



Very cool pics.

[Gravdigr]

I have no snappy and/or smart-ass comment on this subject.

[Beest]

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.

Originally Posted by Scriveyn

I had been wondering how they did it, beacause electron microscopes can only image objects whose surface is electrically conductive. -

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

[monster]

Originally Posted by Beest

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.

But you have done some nice pics of a chrysalis. And stuff.

[Scriveyn]

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

Not at all - thanks B.

[Grismar]

Originally Posted by Brianna

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

The anecdotal evidence offered below shows there's a lot of types at least, prompting a researcher to state there's infinite types and (even more boldly) no two are the same. Knight only proved that there may be subclasses of simple flakes that are likely to have more members (like the plain hexagonal). The poster may be right though, apart from picking at differences at the molecular level, there may even be identical snowflakes at the crystalline level.

It's like saying no two people have the same fingerprints. You can't prove it, but you can show how many variations there can theoretically be. Then you can make an educated guess about how unlikely it is for there to be two or more identical ones.

It's theoretically impossible to prove no two snowflakes are the same. Even if you did have access to all the snowflakes on the planet, there would still be H2O-snowflakes on other planets, in space, in the past, in the future, etc. And besides, it's pointless to prove such a thing.

In fact, it's not what people mean when they say "no two snowflakes are the same". What they're saying is: "the number of possible variations of snowflakes is nearly limitless and most (not all, cue the hexagon) variations seem to have an equal likelihood to occur". But that just doesn't sound like something you'd be telling your kids in the snow .

[xoxoxoBruce]

Wilson A. Bentley, a farmer who was born, lived and died in the small town of Jericho in Vermont was called “The Snowflake Man”.

So Mr Bentley, for 40 years, struggled, persevered, innovated and froze his nuts off. By dedicating his life to science and contributing to the pool of human knowledge, won the respect and admiration of his peers as well as the scientific community.

Then some chica came along and ruined everything....



Yup, sounds about right.

[binky]

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

[middy]

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