According to one theory, the tropopause fold spawns the cyclonic rotation of lower-level air necessary for cyclogenesis: When the slowly rotating stratospheric air is stretched into a more narrow tongue, it spins faster, just as ice skaters turn more rapidly when they bring in their arms.
As anticipated by some, this tropopause fold seems to be a very common event when cyclogenesis processes are occurring,' says Smith.
It is interesting to note that the tropopause fold events we observed over California led to surface ozone measurements in Wyoming exceeding the allowed National Ambient Air Quality Standards value, as described in an "Exceptional Event Demonstration Package" prepared by the State of Wyoming Department of Environmental Quality.
or the investigation of tropopause folds (Yates et al.
Two categories of flow features are considered: (i) Eulerian climatologies of jet streams, tropopause folds
, surface fronts, cyclones and anticyclones, blocks, and potential vorticity streamers and cutoffs and (ii) Lagrangian climatologies, based on a large ensemble of air parcel trajectories, of stratosphere-troposphere exchange, warm conveyor belts, and tropical moisture exports.