NORTHER, a winter wind accompanying the “cold wave” that follows the passage of a cyclone across the United States of America. A warm S.E. or S.W. wind on the east of such a cyclone materially slackens or entirely dies away, and is followed, often suddenly, by the piercingly cold norther. The passage of a cyclone across America is usually from W. to E., and the cyclonic system of circulation would produce these results; but as the North American cyclones usually originate east of the Rocky Mountains, the warm air drawn from the Gulf of Mexico is not only followed by the cold air drawn from the Arctic regions, but the body of cold air slides down the eastern slopes of the Rockies and advances as a solid wedge (the “cold wave”) under the cyclone itself. “Uncomfortably warm in the lightest clothing,” a traveller upon the prairies of Texas may become “uncomfortably cold before he can wrap his blanket around him” (W. Ferrel, A Popular Treatise on the Winds). The temperature may fall 50° F. in twenty-four hours.