Other Instabilities » CSI Conditional Symmetric Instability (CSI)

Thus far, the discussion of stability has focused on vertical displacement of the air parcel. Bennetts and Hoskins (1979) proposed the intriguing concept of conditional symmetric instability (CSI) to explain instability brought about by slantwise displacements of parcels in regions otherwise stable to vertical (convective stability) and horizontal (inertial stability) displacements. The release of CSI results in a slantwise convection and precipitation bands oriented parallel to the geostrophic shear or thermal wind vector. Conditions favoring CSI are often found in the overrunning zones of extratropical cyclones.