sudden stratospheric warming

Sudden stratospheric warming (SSW) is an atmospheric phenomenon that occurs when polar stratospheric temperatures suddenly rise by several degrees (sometimes as much as 50 °C (90 °F)) over the course of a few days. SSW's occur high in the stratosphere, are often associated with Rossby waves and Polar Vortex breakdown and come in varying magnitudes. SSW events are significantly more common in the northern hemisphere than the southern hemisphere.

SSW's were discovered by Richard Scherhag, a German Meteorologist who worked at the Free University of Berlin. Starting in 1951, Scherhag launched radiosondes from Berlin's Tempelhof Airport to research temperature behavior in the upper stratosphere. However, on January 26th, 1952, Scherhag noticed that the upper stratosphere was beginning to warm at an abnormal rate. The warming continued for four days, by which time the upper stratosphere had warmed 33 °C. Scherhag reported this phenomenon in a journal later that year, expressing considerable uncertainty regarding its cause and nature.