Pseudo-RHI of (top) uncalibrated reflectivity factor and (bottom) Doppler velocities collected in the 4 May 2007 Greensburg, Kansas tornado. Note the weak-echo column down the center of the funnel, indicative of centrifuging of hydrometeors and debris. Also note that no data were collected at altitudes below 1.2 km AGL. Data collected by UMass X-Pol.
From my Ph.D. dissertation. Data collected by UMass X-Pol.