Friday, September 18th 2020, 2:11 pm - Here's the science behind Alberta's stunning sunsets.
Alberta has the best sunsets.
And while awesome sunsets can happen everywhere in Canada, they occur relatively frequently in southern Alberta compared with other areas of the country. And it all comes down to the shape of the land.
Stunning sunrises and sunsets most often occur with Chinook conditions, which result from stable, mild Pacific air crossing several ranges of mountains through the B.C. interior before descending onto the Alberta prairie as a mild westerly wind. As this air crosses successive mountain ranges, more and more moisture is “wrung out” of it so that by the time it reaches southern Alberta, it is quite dry.
This is important for making good sunsets, and I’ll explain why in a moment.
The other thing that occurs when a deep layer of stable air is forced over a mountain barrier, is that it rises and cools, resulting in an upper-level cloud -- if there is enough moisture. This is commonly known as a “Chinook Arch,” and it is a smooth, yet textured cloud high above the ground. And now the stage is set for a really good sunset if everything else works out.
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In order to get an excellent, long-lived sunset, the horizon has to be free and clear of cloud. This is why it is important that the low-level air is dry. It enables the unobstructed disc of the sun to shine for as long as possible on the belly of the cloud as it sets. And secondly, the higher the cloud layer is in the atmosphere (as with Chinook Arches), the longer the setting sun can shine on the underside of it, changing slowly from gold, to orange, to red. Bliss!
Here are a selection of some of my favourite photos of sunsets that I have shot on my phone – some from my balcony, and the rest nearby within the Calgary region.
VIDEO: CHASING SUNSETS