Rooms of the Winter Sky: How the Atmosphere Chooses the Weather
In winter, air over the Northern Hemisphere does not move haphazardly; it spends days at a time in the same pattern before rearranging itself. These patterns are like rooms in a maze: the system enters, lingers, then finds a door to another room. Each room has its own weather: somewhere over Europe it is warm and humid, while over Siberia it is frosty and clear.