A cup of boiling water turns into an impressive, dense cloud of snow as Chicago suffers the coldest day in its history. <br /><br />"I threw boiling water straight out of the pot and it froze in mid air!" said the thrower, Melody. <br /><br />Temperatures dropped past -21 degrees Celsius and have been projected to plummet further. <br /><br />The city is in the throes of the polar vortex, which is causing the Chicago River to "steam". States of emergency have been declared in Midwestern Wisconsin, Michigan and Illinois.
