extratropicale

Extratraticale is a term used in meteorology to describe phenomena that occur outside the tropical zones. In practice, it most often refers to extratropical cyclones, large low-pressure systems that dominate weather in the temperate regions of both hemispheres.

Formation and structure: extratropical cyclones typically develop in zones of baroclinic instability where air masses of different temperatures meet along fronts. Unlike tropical cyclones, they do not rely on a warm-core structure; they usually feature a frontal system with warm and cold fronts and can become occluded in their mature stage. Their energy comes from horizontal temperature gradients and vorticity advection rather than from heat stored in the sea.

Characteristics and impacts: these systems are associated with broad wind fields and widespread precipitation, which can be rain or snow depending on season and latitude. They often bring strong winds, heavy rainfall, flooding, coastal surge, and winter storms. Their evolution includes intensification along fronts and sometimes rapid deepening, especially in the presence of a jet stream.

Distribution and climate context: extratropical cyclones form mainly between roughly 30 and 60 degrees of latitude in both hemispheres. They are common in the North Atlantic and North Pacific, shaping the weather of Europe, North America, and parts of the Southern Hemisphere’s mid-latitude regions. They contrast with tropical cyclones, which derive their energy from warm sea temperatures and have a warm core.

Relation to related phenomena: the term also encompasses subtropical cyclones and transitional systems that evolve from tropical to extratropical as they move into higher latitudes. Extratropical weather patterns are a fundamental component of temperate climate dynamics.