Andrew Vaughan / Canadian Press via AP
A ferry and tugboat cross the harbor in Halifax, Nova Scotia, on Monday, Jan. 24. Fog occurs when very cold air drifts across relatively warm water.
Toby Talbot / AP
A frost-covered horse stands in a pasture in Calais, Vt., on Monday, Jan. 24. Cold temperatures prompted schools around the Northeast to delay openings and some canceled classes altogether.
Richard Hertzler / Lancaster Intelligencer via AP
A pedestrian stops to admire ice that formed on a fountain at Penn Square in Lancaster, Penn., on Monday.
Bill Sikes / AP
Fog rises off a pond in Marlborough, Mass., on Monday as ducks swim at sunrise.