Mesocyclone Evolution and Tornadogenesis: Some Observations

摘要: Abstract Updraft mesocyclones in tornado-producing thunderstorms form along convergent and cyclonically sheared boundaries that separate inflow air entering forward rear storm quadrants. Maximum tangential flow resides girding wind bands, averaging usually less than 3 km radius (depending upon the development stage), strengthen near ground during toradogenesis. Strong inflow, concentrated at or below cloud base, is maintained throughout intensification period. During tornadic phase parent mesocirculation exhibits an apparent “breakdown", i.e., a transition from single-cell to two-cell axial structure. At this critical period small eddies may appear within elongated mesocyclone core some become tornado and/or grow large proportions. Tornado dissipation result cyclonic rotation of major horizontal axis which chokes supply detaches principal updraft. Another mechanism for inv...