The process of cyclone formation and intensification is described as Cyclogenesis. The formation of Extratropical cyclones comes as waves in large regions of enhanced midlatitude temperature contrasts which are called baroclinic zones. These zones contract to form weather fronts as the circulation of the cyclone closes and gets more intense. Later in their life cycle, cyclones form what is called an occluded front. The cyclone's track is then guided over the course of an 2 to 6 day life cycle by its steering flow of the polar or subtropical jetstream. Cyclones destroy many things when they come into contact with land such as crops, buildings, trees, etc.