• Extratropical Cyclone development and tracks have preferred regions.
  1. In the lee side of major mountain ranges. Consider the conservation of potential vorticity argument. (Chap. 9.2)
  2. Near the east coasts of continents. Oceanic western boundary currents (WBCs) occur here. Examples: Gulf Stream (N. America); Kuro Shio (Asia). Consider these factors:
     1. a large surface T contrast between cold continent (winter) and the warm tropical/subtropical waters of the WBC. This provides a source of lower tropospheric baroclinicity.
     2. strong sensible heat fluxes. These lower the static stability which makes vertical motion easier. (Vertical motion is associated with development many times in this course.)
     3. strong latent heat fluxes. Eventually, much of the latent heat is released in the warm sector where it increases the (available potential) energy of the cyclone.
  3. cyclone tracks are eastward with a slight poleward component. See supplementary notes for more comprehensive diagrams than those in the text.

Back to ATM 111 homepage