A polar vortex is engulfing the US. Here's what that really means, and why these events might be getting more common. - Business Insider

A polar vortex is engulfing the US. Here's what that really means, and why these events might be getting more common.  Business Insider

The US is staring down a record cold snap caused by the polar vortex. Here's what makes polar-vortex events so dangerous and why we may see more of them ...