"Snowflake" Bentley and the Sound of Snow

We’ve just had the coldest, snowiest winter in a long time. A great opportunity to look at some of the science (and beauty) of snow. 

We’ve all heard that no two snowflakes are alike. The discoverer of this factoid was an unlikely candidate. Wilson Bentley, “The Snowflake Man”, was a self-educated farmer who adapted a microscope to a camera and pioneered microphotography. His photographs of snow crystals attracted world-wide attention. He photographed over 5,000 snowflakes – no two identical.  

Wilson Bentley with his bellows camera.

More Bentley photographs of snowflakes

Many, but not all snowflakes look like these six pointed stars. There are many other forms. 

Professor Ken Libbrecht of Caltech (California Institute of Technology) could claim to be the modern “Snowflake Man”.

 

The diagram below from Professor Libbrecht's website shows the many forms of snow crystals and how different ones are likely to form at different temperatures. 

  

Most crystals are six-sided because of the geometry of the water molecule, with two hydrogen atoms bonded to an oxygen atom. Any two snowflakes in nature have experienced different paths on their journey to the ground, so are different from each other. But the six sides, or arms, are almost identical to each other because all six sides are subjected to almost identical atmospheric conditions in their path down to the ground. Dr. Libbrecht has grown pairs of snowflakes in his lab, subjecting them to the same conditions. And, sure enough, virtually identical ‘twin’ snowflakes are created. Go to the link below and click on "Growing Twin Snowflakes" to see some spectacular videos showing the crystals growing side by side. 

 http://www.snowcrystals.com/identicaltwins/identicaltwins.tml

This winter we had lots of opportunities to walk on squeaky snow. If you live in a cold snowy region you know what I’m writing about. If you don’t: walking on snow is very quiet unless the temperature is quite low, and then you hear a distinctive squeak when you tread on it. So what is it that makes the noise?

Oddly, for such a common phenomenon, there isn’t a single agreed-upon explanation. Or perhaps not so oddly. As one scientist observed on the subject “They don’t give out Nobels for explaining why snow squeaks”.

There is general agreement that snow squeaks at temperatures of -14°C and below, and not above that temperature.

The most likely explanation is that the squeaking is made by the breaking of snow crystals as they are forced into each other. There’s less agreement on why the snow is silent above that temperature.

 One common explanation is that it’s the pressure of your foot. Increasing pressure lowers the melting point of ice. So at temperatures from 0°C to -14°C enough of the ice in the snow crystals will melt and they’ll slide past each other quietly. One problem with this explanation: pressure doesn’t change the melting point all that much; not enough to melt ice at -14°C.

A more likely explanation is this: the surface of ice is always covered by a layer of water. The colder the temperature, the thinner the layer. At -14°C it’s only one or two molecules thick. When the temperature is higher than that the crystals are lubricated by the water and slide quietly past each other as they compress.

Michael Faraday (most famous for his work on magnetism and electrochemistry) first suggested in the 1850’s that this layer of liquid exists. Scientists have subsequently confirmed it. 

Mr. Michael Faraday (he turned down a knighthood, preferring to remain “plain Mr. Faraday to the end”) at the age of about 70. He was self-educated, initially through reading books during his apprenticeship as a bookbinder and bookseller.

This layer of water is also the explanation of why ice skates glide. For more on that, look (again?) at my blog entry in February of 2017 on the subject.

http://sci-why.blogspot.com/2017/02/surprisingly-slippery-science.html

And the best news about all of this is that Spring is here and we won't be hearing squeaking snow for many months.

Black Hole Photo!

There's a phenomenal image going round the Internet, and it's called the first-ever photograph of a black hole.

Well, it's not exactly a photograph, not like if you pointed your cell phone camera at the moon as I did last month. A word to the wise: it's easy for a full moon to be sooooooo bright it washes out the image to be nothing more than a white circle in a black sky, instead of what my eyes could see, which was a moon with visible craters and maria in a night sky speckled with stars. Technology needs to be managed to make useful images.

And the technology managed to make that orange image of hot, bright dust and gas circling a huge black hole? Well, it was managed in a number of ways. One of the leaders of a team creating an algorithm (a set of rules) to make that image was Dr Katie Bouman, when she was a graduate student at MIT.

Here's a photo of Dr Bouman that she shared on her Facebook page.

The team working to make this image was the Event Horizon Telescope, and you can see their website at this link, which is very useful for scholars and students. If you're looking for a popular science discussion like the ones on Twitter at #EHTBlackHole or  #EyeofSauron, you'll want to go to the BBC website for a terrific article on Dr Bouman, the team, and their project. There's even a short video of her TED Talk. Here's a link!
Another good place to learn is on Dr Bouman's Facebook page at this link. Scroll down to see several posts about the project and how information from many international telescopes was used to make this image.


The Neuroscience News Website quotes Dr Katie Bouman as saying that photographing a black hole is "equivalent to taking an image of a grapefruit on the moon, but with a radio telescope." You can follow Neuroscience News on Twitter at @NeuroNewsResearch, or check out this link to read their posts on Facebook.

Happy Birthday to Us... Almost

By Claire Eamer

Last week, I was delving around in old Sci/Why blog posts, looking for a dinosaur photo to illustrate L. E. Carmichael's post on the enormous Tyrannosaurus rex unearthed in southern Saskatchewan, Move Over SUE, There's a New T. rex in Town. A few years ago, I had visited the fossil's home museum in Eastend, a small town set among the low, rolling hills of southwestern Saskatchewan's shortgrass prairie. I knew I had written a blog post about it, but I couldn't remember when.

Well, I found it. And it was longer ago than I realized. In fact, that post, Seeing the Real McCoy... er, McDino, appeared in Sci/Why's first summer, 2011. I also realized we're about to have a birthday. Sci/Why was launched in April 2011. We're about to turn eight years old! There should be cake, shouldn't there?

Not many blogs will show you this, but Sci/Why will. That is dinosaur poo!
Specifically, it's fossilized T.rex poo -- a coprolite, in polite company -- and it's the
first T.rex coprolite ever found. Here it rests safe in a display case at the museum
in Eastend, Saskatchewan. Claire Eamer photo 

The website intro (just over there on the right and up a bit) credits me with the idea for Sci/Why, but the truth is, it started because I'm lazy. A handful of us kids' science writers were at a conference when one of us said, "I think someone should set up a blog about Canadian science writing for kids." Because, you see, there's a lot of it, and it's actually very good. But a blog sounded like a lot of work -- and I'm definitely not in favour of a lot of work -- so I said, as quickly as possible, "Group blog. It should be a group blog!" (You see what I did there, eh? It's the Tom Sawyer you-will-love-painting-this-fence-for-me thing.)

And we did. And it's still going. What you are reading right now is Sci/Why blog post #436. As I write this, our all-time total page views number 436,724.

Want a few more stats? Of course you do!

Our most popular column ever, which also came out that first summer, is How big can an earthquake be? by Craig Saunders. So far it has garnered 40,586 page views, and it's in the top five columns almost every week -- especially if there are earthquakes in the news.

Another biggie from that first year is Joan Marie Galat's post, Why constellations and astronomy are important, from October 20, 2011. It has received 19,885 page views (as of this moment), and it too shows up regularly in the top five.

Both those posts address topics that turn up again and again in the news and in the school curriculum. But Shar Levine's piece on the Eleanor of Aquitaine Sundial is a bit more off the beaten track. Still, it has earned 9,393 page views and counting. And Helaine Becker's rant about American children's publishers shying away from the topic of evolution, A Call to Arms -- and Flippers, Too, has almost as many page views. In fairness, Helaine in full rant is always entertaining.

The big hitters in the page-view stats are the older columns, since they've had time to be discovered again and again. But some of our more recent posts are doing very well indeed. Adrienne Montgomerie's Iceman CSI: Tales from a 5300-year-old man, which dates from October 2016, has more than 2000 page views. So do several of Jan Thornhill's immaculately researched and beautifully illustrated posts. Check out her Colourful Wood: Spalting Fungi from last year to see what I mean.

Over the past eight years, we've had writers come and go as their interests and time constraints changed. Usually there are about eight or nine regular contributors, and a few more people who send in a blog post when they have time. We try to update the blog every Friday -- but we remind ourselves that the world won't end because we've missed a Friday. This should be fun -- for us and for you. We hope it is and continues to be. Happy Blog Birthday to all of us!

Yours fondly, Claire (and the rest of the Sci/Why crew)

Move Over SUE, There's a New T. rex in Town

Photo by Claire Eamer

by L. E. Carmichael

Of all the dinosaurs in all the world, SUE the T. rex might be the most famous. The most complete T. rex skeleton ever found, SUE is likely also the most well-traveled. Her bones, or at least casts of them, have been displayed all over the world. The casts I saw in Nova Scotia came with bilingual displays written in English and Arabic!

But there's a new king of the dinosaurs in town, and his name is Scotty.

Named after a bottle of Scotch the scientists toasted his 1991 discovery with, Scotty is only 65% complete, compared to SUE's 90%. But he stands out for another reason - as far as we currently know, he's the biggest carnivore ever to walk the earth.

As any forensic anthropologist will tell you, there's a certain amount of instinct and guess-work involved in reconstructing height and weight from nothing but bones. But measurements of Scotty's femur (the long, heavy bone from his thigh) suggest he was in the ballpark of 19,500 pounds - almost a ton more than SUE.

He was also a senior citizen - at approximately 28 years old, Scotty lived longer than any other T. rex we currently know about. And he was a tough old dude, surviving a broken rib, fractured tail bones, and an infected jaw. Those injuries showed signs of healing, meaning they likely weren't his ultimate cause of death.

Now that Canadian palaeontologists have had a chance to study him, Scotty will be making his public debut at the Royal Saskatchewan Museum this May.  No word yet on whether he'll be joining his cousin SUE on tour!

An Iceberg of Women in Science

Grace Lockhart was the first woman in the whole British Empire to graduate from a university. It was 1874 when she got a science degree up at Mount Allison University in New Brunswick, Canada, but it was almost another 50 years before all women got the right to graduate or even to attend classes in Canada (and the UK). Nicaragua started allowing women in university about 100 years before that and Italy started about 700 years earlier. Once women could graduate, they still usually didn’t get credit for their discoveries and inventions. But that didn’t stop some of the brightest female minds from contributing to human knowledge and technology.

We hear little bits now, often in form of stories about the wives who innovated beside their husbands, brothers, and employers, did the field work, catalogued all the specimens, built the telescopes, designed the experiments, or crunched the data. The information is coming out now. Slowly.

Blockbuster films like Hidden Figures, memes that give credit where it is due, and announcements of “all female firsts” like the space walk this month led by Kristen Facciol,

a female flight controller from the Canadian Space Agency give us the sense that there is a whole iceberg of information waiting to be revealed about female scientists throughout history.

scientist: "does everyone here know what Watson and Crick discovered?"
me from back of room: "Rosalind Franklin's notes"

— Robby Kraft (@RobbyKraft) May 3, 2016

My high school science teacher 30 years ago taught me about Madame Curie’s experiments with radiation, but that was the only thing I’d ever heard about a woman doing science. It’s getting easier to learn more about women doing science throughout history: buy books about them; watch movies about them; ask questions about them at the science centre; ask teachers about them. The more interest we show, the more answers will get shared.

Search this blog for “women” and you’ll find several posts. A Mighty Girl regularly posts stories and cool posters about female scientists and inventors and all kinds of other interesting women, both old and current. Brain Pickings has great stories about women in science, as does scientificwomen.net, and you’ll find great summaries on YouTube, too. Take a look around, then tell others the cool things you learned.

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by Adrienne Montgomerie
photo from Pixabay