And you thought you were cold, shuffling between your apartment (where there is heat and blankets and hot chocolate) and the subway (where you are wearing a coat and mittens and kept warm by the bodies of hundreds of complete strangers!) Try being a 167-foot tall waterfall caught in the Polar Vortex. Niagara Falls is freezing!  And we mean that literally. Niagara Falls is literally freezing. The waterfall "partially froze" this past Tuesday, when the Polar Vortex plummeted temperatures to a record -2 degrees and ice began forming on the U.S. side of the falls.  These very cool pictures were taken by Reuters photographer Aaron Harris and you would do well to remember that it could always be...