Tornadoes - Severe Convective Storms and Tornadoes: Observations and Dynamics - page 358

Figure 6.40. (Left) Schematic of the ''Ward'' tornado simulator (from Church et al., 1979).
(Right) Large tornado simulator at the Museum of Science and Industry in Chicago, IL
(photograph by the author).
the azimuthal direction, where it acquires vertical vorticity. Neil Ward at NSSL
pioneered the use of such laboratory models. While there are a number of
parameters that are not allowed to vary (by design, for geometric similarity with a
convective storm), such as the size of the opening into which horizontally
converging air at the bottom turns into the updraft aloft, measurements have been
made that bear good resemblance to observations of some real tornadoes.
While laboratory models allow us to conduct controlled experiments with
tornado-like, columnar vortices that make contact with the ground, we do have
the problem of measuring wind variables and thermodynamic variables without
disturbing the flow so that the vortex structure is not altered by the measurements.
In effect, we have a problem similar to (but not directly analogous to) that in
quantum physics in which the better one knows the momentum of a particle, the