Tornado Simulation (IMAGE) University of Wisconsin-Madison Caption When a tornado is fully formed, the simulation reveals several structures that make up the tornado, including the streamwise vorticity current (SVC), thought to be a main driver of the tornadic activity (seen in yellow). Credit UW-Madison Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.