What's the real colour of snow? Weather myths busted on The Nature of Things
Watch the The Nature of Things on Thursday at 8 p.m. on CBC TV
Can a plane survive a lightning strike? And where's the safest place to hide during a tornado? Scientist Jennifer Gardy's new documentary, In the Eye of the Storm, looks at the myths and science of weather on CBC TV's The Nature of Things. The show airs Thursday at 8 p.m. on CBC TV.
It's the subject Canadians most love to talk about. Cold or hot, wet or dry, wherever you live in Canada, it's an obsession. And like any obsession tackled by Gardy — from dieting to beauty — weather spawns an extraordinary number of claims including:
- Can a cricket's chirp reveal the temperature?
- Are highway overpasses safe shelters in a tornado?
- Can lightning destroy a plane?
- Is the safest place to hide during a thunderstorm in your home?
Gardy answers these questions and more in her interview with the CBC's Conrad Collaco. You can listen to the full interview by clicking the image at the top of this page or read an edited and abridged transcript below.
Scientist Jennifer Gardy, The Nature of Things
Q. What made you want to focus this documentary on the weather?
It is the most quintessentially Canadian of topics. We love to talk about the weather. Somewhere in Canada, right now, somebody is having a conversation about the weather, probably a few thousand people talking about the weather. This is Myth or Science 4 that we have done for The Nature of Things. We try to tackle things relevant to people's daily lives. We show them the science behind these myths. They say that's news I can use in my every day life. We've tackled things like diet and exercise. Weather seemed to be the next natural target.
What did you learn, as you travelled the globe, from the many weather researchers you talked to?
We thought 'what are the types of weather Canadians are most interested in?' Top of the list is snow. We travelled to the Colorado Rockies and we looked at whether snow crunches louder on a cold day. We talked to a glaciologist, a fellow who studies snow and ice for a living. To get our really cold temperatures we visited the National Ice Core lab in the U.S. where they store ice core samples drilled from all over the world that keep a record of our planet's climate history. It is literally a really cool facility. It's about -45 C in there. And we found out that yes, snow does sound different on a cold day.
You also looked at the colour of snow. Does snow look different than we think it does?
Yes. It's a confusing issue. When you take snow and let it melt — your poor snowman in the front yard — the snowman becomes clear when he goes back into his liquid form. So, how is it that something clear in its liquid form becomes something opaque or white? We perceive colour through light, basically a rainbow with all the colours of the spectrum. When light hits an object, the object will absorb a bunch of the light spectrum but reflect back a part of the spectrum and that's what allows us to see something as having a colour. A red apple will absorb every colour but red. It will bounce the red light back and we perceive the apple as red.
What happens with snow is that all colours of the spectrum enter a snow pack and the light bounces around so much between all of the snow crystals that no one colour ever splits out, so it bounces back to us as all of the colours of the spectrum, not just one. When that happens, you get white light and the perception of white snow.
And you looked at the shape of raindrops — what did you discover?
If you give a child, or heck even an adult, a crayon and ask them to draw a raindrop everyone will draw a teardrop shape. We went to Manchester to a researcher who has built this very cool vertical wind tunnel. He can stop a raindrop in mid flight. We took a high-speed video camera and filmed a raindrop in mid-air. What we found is that the shape is not a teardrop but rather a flattened sphere shaped like a tiny hamburger.
What about how planes in flight survive lightning strikes?
We went to a lightning laboratory in Cardiff, Wales. The two men who work there get to blow stuff up all day long. We looked at why, when lightning strikes a tree, very often it will wind up ripping the tree in half and scorching it — so why doesn't this happen to planes? We know they are being hit by lightning strikes regularly. They do fly through thunderstorms. The answer is something called a Faraday cage, a copper mesh that is built into the aircraft's skin. When a bolt strikes an airplane, that Faraday cage dissipates the lightning's energy throughout the plane. So, it doesn't cause any localized catastrophic damage. It dissipates and usually comes out through the tail.