the development of a mid-latitude cyclone according to the norwegian model begins along the frontal boundary.
the development of a mid-latitude cyclone according to the norwegian model begins along the​?
frontal boundary
there are two models of cyclone development and lifecycles in common use—the norwegian model and the shapiro-keyser model.





















































section::::cyclone evolution.:norwegian cyclone model.





















































of the two theories on extratropical cyclone structure and life cycle, the older is the norwegian cyclone model, developed during world war i. in this theory, cyclones develop as they move up and along a frontal boundary, eventually occluding and reaching a barotropically cold environment. it was developed completely from surface-based weather observations, including descriptions of clouds found near frontal boundaries. this theory still retains merit, as it is a good description for extratropical cyclones over continental landmasses.
extratropical cyclone
horizontal deformation in mid-latitude cyclones concentrates temperature gradients—cold air from the north and warm air from the south. horizontal shear has two effects on an air parcel; it tends to rotate the parcel (think of placing a wheel at a point in space and as the wind blows, the wheel rotates) and deform the parcel through stretching and shrinking. in the end, this can also tighten temperature gradient, but most importantly, this rotates a concentrated temperature gradient for example, from the x-axis to the y direction. within a mid-latitude cyclone, these two key features play an essential role in frontogenesis. on the west side of a typical mid-latitude cyclone, there are northerly winds (associated with cold air) and east of the cyclone, southerly winds (associated with warm air); resulting in horizontal shear deformation. in the end, this results to concentrate a cyclonic shear along a line of maximum shear (which in this case is the birth of a cold front). on the eastern side of a cyclone, horizontal deformation is seen which turns into confluence (a result of translation + deformation). horizontal deformation at low levels is an important mechanism for the development of both cold and warm fronts (holton, 2004).
frontogenesis