Are two snowflakes ever the same?
While most of Radio IQ’s listening area hasn’t seen a significant snowfall so far this winter, there is still certainly time for that to happen. Some parts of Virginia have recorded snowfalls well into March, after all.
So, there’s still time to see one of the most beautiful sights in all of nature: the snowflake.
Snowflakes form when liquid water droplets inside a cloud start to freeze as the temperature within the cloud itself begins to drop below the freezing point.
“One droplet freezes, and it will start to grow by absorbing water vapor from the air around it. The liquid droplets around it will evaporate and an ice crystal will start to grow. And it takes about 100,000 droplets all evaporating to make one snowflake. And this is going on over and over again in the cloud in different places.”
Kenneth Libbrecht is a professor of physics at CalTech who studies the molecular dynamics of crystal growth – including how ice crystals grow from water vapor. That’s essentially the physics of snowflakes.
I asked him if the old saying – “no two snowflakes are alike” – is actually true.
“The number of possible ways of making snowflakes is just astronomically large. And so, the probability of any two alike is just zero. It’s a lot like fingerprints. It doesn’t take many features on a fingerprint – like 10 – and you’ve narrowed it down to one person out of 10 billion. It’s the same with snowflakes except there’s a lot more than 10 features – there’s 100 features – and so now, it’s almost an infinite number of possibilities.”
Science has a pretty good grasp on what causes snowflakes to form. But, what causes their actual structure – all the way down to the molecular level – is still being researched. That has been a big part of Libbrecht’s research.
“When you get to the molecular level on these things, everything is super fascinating and super hard to understand.”
He has developed a model over the years that can pretty accurately determine what shapes snowflakes will take under certain conditions. Temperature and humidity appear to be the biggest factors.
“At low humidity levels, the crystals are more blocky – nice, faceted crystals. And as you go to higher humidities, you get a lot of branching. And really high humidities, you get falling from the sky what are called fern-like stellar dendrites.”
Snowflakes have a harder time growing in areas with high wind. On the temperature side, it seems as if the best development occurs around -15 degrees Celsius – or 5 degrees Fahrenheit.
“Most cities in the U.S. don’t get that cold very often, so when I would photograph, I would go up to northern Ontario, sometimes Alaska. But, if you live in a cold climate, sometimes you just have to wait until a nice, cold day and then you can go outside and just take a walk in the woods and really see some nice stuff.”
Libbrecht says intrepid snowflake watchers can bring along a magnifying glass when they go outside on a snowy day, which will give you a whole new world of things to look at any flakes that land on your sleeve.
“And then you can take really nice photos just with a cell phone camera now. Some of the newer ones have macro lenses built in and even with an older phone, you can clip on a macro lens. And that’s a good place to start.”
Hopefully Virginians will get a chance to do that before too long.
Check out some Libbrecht's website – snowcrystals.com. You can find even more amazing photos and an even deeper dive into the science behind snowflake formation there.
NOAA: 2022 was the sixth-hottest year on record
The National Oceanic and Atmospheric Administration – or NOAA – has released its annual look at global temperatures.
In 2022, earth’s average land and ocean surface temperature was 1.55 degrees above the 20th century average of 57 degrees Fahrenheit. That makes 2022 the sixth-warmest year on record since 1880.
It is also the 46th year in a row where global temperatures rose above the 20th century average.
Some other notable findings from the data:
- Antarctic sea ice extent, or coverage, reached a near-record low point in 2022. Only 1987 had less ice coverage. The Arctic reached the 11th-smallest annual extent in the 1979-2022 data record.
- There were 88 named tropical storms across the globe last year – which is pretty close to average.
- December 2022 was notably warm. It ranked as the eighth-warmest December in NOAA’s record – which spans more than 140 years.