Frost quakes, ice storms, blizzards: What's next?
Frost quakes? polar vortex? It’s really something when you hear the public using these terms on a regular basis. It has been quite the winter across Canada with ice storms, blizzards, frigid temperatures and snow hurricanes -- and it doesn’t look like the active pattern will be dying down.
First, let’s get some facts straight about this “polar vortex” everyone is going on about. The polar vortex is by no means something new or something rare. It is a permanent atmospheric feature all year round existing at the North and South Poles. They are a circulation (on a planetary scale, not a mesoscale like a tornado, so it’s big) and are located from the middle troposphere to the stratosphere so it is an upper level phenomenon. The polar vortices are strongly reliant on large scale temperature gradients so in the winter, they are at their strongest due to the temperature gradient between the equatorial regions and the poles. The term “polar vortex” has been used in scientific papers since the 1940’s.
If you recall two winters ago when winter was absent from the majority of North America, this was partially (but not completely) due to the fact that the polar vortex in the North Pole region was “stuck” up there so the colder air was bottled up and not drifting into southern latitudes. Here's a brilliant explanation by Weather Network meteorologist Doug Gillham about what the polar vortex is and why we have been so cold.
Part of the reason we have been so cold is due to cross-polar flow: cold air coming straight from Siberia. But why is Siberian air colder than Canadian Arctic air? Doug explains:
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