P6.5 Behind the "supertwister": experiences in science education at NCSA

Wednesday, 6 October 2004
Matthew S. Gilmore, University of Illinois, Urbana, IL; and R. Patterson, G. S. Romine, L. J. Wicker, R. B. Wilhelmson, A. Betts, D. Cox, L. Cronce, M. Hall, L. Leonard, S. Levy, and M. A. Straka

We present "behind the scenes" animations of simulated tornadogenesis and tornado evolution, similar to those recently featured in the PBS NOVA television program, to illustrate the following principles:

1) Development of early supercell rotation,

2) Occlusion of pre-tornadic low-level rotation,

3) Baroclinic generation of vorticity along the forward-flank gust front for tornado-bound parcels,

4) Descent of pre-tornadic rotation and the rear-flank downdraft, and

5) Merging of several "seed vortices" along the forward-flank downdraft gust-front into the pre-tornadic and the mature tornado.

Several different types of backward- and forward- airflow-following trajectories are utilized to isolate important air parcels and regions involved in rotation:

1) Weightless balls (colored by pressure),

2) Smaller weighted "dust" of various sizes (triggered by surface windspeed thresholds),

3) Spinning pointed ribbons (with spin proportional to local vorticity),

4) Pointed tubes (colored by updraft speed), and

5) Surface wind vectors (lean proportional to windspeed; color proportional to temperature).

In addition, simulated radar reflectivity and volume-rendered cloud provide context with the airflow trajectories and can be used for comparison with radar or video documentation of observed tornadic storms.

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