Thursday, September 12th 2019, 3:30 pm - Canada, we need your sunsets.
Ask Canadians for a tell-tale sign that summer is coming to an end, and you'll probably hear at least one person say "It gets dark earlier."
The sun setting earlier is a decided negative for many Canadians, as months of long winter nights loom ahead. But there is a silver -- or maybe golden -- lining to it all.
Autumn sunsets are some of the best we get in Canada, thanks to the return of clearer, cleaner air. And forecast models are hinting that we should be getting the best sunset in North America on Thursday, right over Ontario.
You need a few factors to come together to get a brilliant, beautiful sunset. As the sun dips lower in the sky, rays of light travel through a thicker slice of the atmosphere to reach our eyes. That longer trip means the rays bump into more particles, and the light scatters more; that is, it's better separated into its component colours. Short wavelength colours, like blue and green, have a harder time making it through this atmospheric maze, while longer wavelengths -- red and orange -- sail on through.
It's true that dust, smoke, and other pollution in the low atmosphere can make for a redder sunset because they're better at scattering yellow and orange light. But that mutes the overall vividness of the sunset; red-only sunsets lack the contrast of a multi-coloured show. Cleaner air makes for more vivid oranges and reds -- spectrally pure. Drier air does, too; in higher humidity, water vapour will make for more pastel colours.
The model data shown in the map above is drawing some of its assessment from the moisture and source region of the air mass, with blues and greens representing more humid air, and reds and yellows showing the drier, cleaner air.
But the proof is in the pudding, as they say, and we want you to be the judge. Head outside Thursday night and #ShareYourSunset. Not sure when the sun will set in your area? Check out the map below, then let us know what you see by uploading your shots to our gallery, or tagging @weathernetwork on social media with #ShareYourSunset or #ShareYourWeather.
Are you in Ontario, where the model says the sky should be best? Will the Prairies big skies reign supreme? Will orange sky and blue water take the title in the Maritimes? Let's see those sunsets, Canada.