Yes, Ottawa, it's a polar vortex again

You can now officially blame a polar vortex for Ottawa’s frigid temperatures.
But wait, what’s a polar vortex?
Most of Canada has a blanket of cold air that has pushed its way down from the Arctic, where it spends much of the year going around in circles (that’s the “vortex” part) and not bothering us at all.
This air moved south over Christmas. We used to call this a cold spell, mostly. The polar vortex term caught on in 2014 when an especially persistent mass of A