page_title: Cyclogenesis
section_title: Norwegian cyclone model
hierarchical_section_title: Cyclogenesis / Extratropical cyclones / Norwegian cyclone model
context_page_description: Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere. Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cyclone, and at any size from the microscale to the synoptic scale.
  Tropical cyclones form due to latent heat driven by significant thunderstorm activity, developing a warm core.
  Extratropical cyclones form as waves along weather fronts before occluding later in their life cycle as cold core cyclones.
  Mesocyclones form as warm core cyclones over land, and can lead to tornado formation. Waterspouts can also form from mesocyclones, but more often develop from environments of high instability and low vertical wind shear.
  The process in which an extratropical cyclone undergoes a rapid drop in atmospheric pressure in a 24-hour period is referred to as explosive cyclogenesis, and is usually present during the formation of a nor'easter. The anticyclonic equivalent, the process of formation of high pressure areas, is anticyclogenesis. The opposite of cyclogenesis is cyclolysis.
context_section_description: The Norwegian cyclone model is an idealized formation model of cold-core cyclonic storms developed by Norwegian meteorologists during the First World War.  The main concept behind this model, relating to cyclogenesis, is that cyclones progress through a predictable evolution as they move up a frontal boundary, with the most mature cyclone near the northeast end of the front and the least mature near the tail end of the front.
caption: An upper level jet streak. DIV areas are regions of divergence aloft, which will lead to surface convergence and aid cyclogenesis.
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