Wikipedia:Today's featured article/December 1, 2006

Extratropical cyclones are one part of the broader family of cyclones. They are defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth, having neither tropical nor polar characteristics, and are connected with fronts and horizontal gradients in temperature and dew point otherwise known as "baroclinic zones". Extratropical cyclones are the everyday phenomena which, along with anticyclones, drive the weather over much of the Earth, producing weather ranging from cloudiness and mild showers, to heavy gales and thunderstorms. Extratropical cyclones form anywhere within the extratropical regions of the Earth (usually between 30° and 60° latitude from the equator) in one of two ways; either through cyclogenesis or extratropical transition. (more...)

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