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WEATHER U: Pastel rings – 'plane' to see

Julia Thomson of Ottawa took this amazing photo last month on her descent to the Stanfield International Airport in Halifax. Her family suggested she send this in, with hopes that I could explain the colourful ring around the plane’s shadow.
Julia Thomson of Ottawa took this amazing photo last month on her descent to the Stanfield International Airport in Halifax. Her family suggested she send this in, with hopes that I could explain the colourful ring around the plane’s shadow. - Contributed

By now you must know how much I love clouds. They are beautiful, and they can teach us a lot about what’s happening overhead. But what if you’re above the cloud looking down?  

Earlier this month I received an email and photo that I just had to share with you:

“My name is Julia from Ottawa, and as I was arriving in Halifax to visit my family on Saturday, November 16, I saw this natural wonder out of my window. This photo was taken during the descent towards the Halifax airport. My family suggested I send this in, and that you might know how this phenomenon happened! Looks like the shadow of our plane inside a rainbow.”

What a great photo Julia. That lovely ring has a name – it’s called a “Pilot’s Glory” or “Glory of the Pilot” because most times, pilots are the only ones who get to see it!  It’s often just grey so you hit the jackpot with some iridescence and rainbow-like colours.

With our feet on the ground, it’s not uncommon to see a rainbow arch across the sky following a rain shower. Rainbows are a result of reflection, refraction and dispersion of light in water droplets. 

For decades, the science behind a “glory” was not well documented. We now know that most of the light that forms a glory doesn’t pass through the droplets. The main cause of a glory is a process called tunneling where the sunlight passes close enough to a droplet to create electromagnetic waves within it. Those waves bounce around inside the droplet and eventually get out, sending out light rays that make up most of the glory that we see.

Besides being pretty to look at, Pilot’s Glory is a science lesson. The ring is telling you that the cloud is not only made up of ice crystals but liquid, too!  Why is this important?  Well, if the temperature in the cloud is around the freezing mark and the plane descends through the cloud, icing is likely to occur. Pilots do their best to avoid these conditions.

Years ago, when I briefed pilots at the Macdonald-Cartier International Airport in Ottawa, a pilot told me that if you see a Pilot’s Glory it means you have a guardian angel flying with you.



Cindy Day is the chief meteorologist for SaltWire Network.


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