Animation of the weather of winter of 2009/2010 (left) and 2013/2014 (right) from the Met Office Unified Model. The panels show 250 hPa wind (corresponding to an altitude of approximately 10km coincident with the Jet Stream), and 850 hPa actual temperature. The animations run from 1 December to 28 February with a 3 hour time-step. Courtesy David Fereday, Met Office Hadley Centre.